Photographing Rotifers

by Dr. Robert Berdan

July 24, 2018

Euchlanis dilatata - a rotifer common in pond water by Robert Berdan ©

Euchlanis dilatata (Monogononta, Ploima, Euchlanidae) - a rotifer common in pond water (one micron = 1\1000 of millimetre) Differential Interference Microscopy (DIC) using a Zeiss Axioscope microscope.

Introduction to the Rotifers

An interest in Rotifers started after microscopist Anthony van Leeuwenhoek (1632-1723) described them in a letter from 1687. These microscopic organisms live in water including ponds, creeks, rivers, lakes, soil, water associated with moss, liverworts and lichens. They are also found in a more limited extent in saline waters. They range in size from 40 microns (0.04 mm) to about 2,000 microns (2 mm) in length so a light microscope is required to observe them. Rotifers have exisited for at least 35-40 million years as they have been identified in fossilized amber (Waggoner and Poinar, 1993). They only live about 1-2 weeks. These organisms are not well known though I think they should be.

Squatinella rostrum (Rotifera: Monogononta, Ploima, Lepadellidae) by Robert Berdan ©

Squatinella rostrum (Rotifera: Monogononta, Ploima, Lepadellidae) note 2 red eyes on the side of the head. DIC microscopy.

It's estimated there are about 2000 species of rotifers, most live in freshwater. They can occur in numbers of up to 5000 per litre. They play a role in nutrient recycling, they are used in testing water toxicity, and are also used to feed fish larva and are even sold in some pet stores. In research they are used to study aging, suspended animation (anhydrobiosis), and are used as bioindicators of toxicity. They have been referred to as "Time travellers", because when in the dessicated state as a cyst or egg they can survive for decades without any signs of aging. Some have survived frozen in glaciers for over 24 thousand years (L. Shmakova et 2021 Current Biology).

Bedelloid rotifer photographed with positive phase contrast by Robert Berdan ©

Bedelloid rotifer photographed with positive phase contrast Olympus E- Microscope 200X

Bdelloid rotifer Negative Phase contrast by Robert Berdan ©

Bdelloid rotifer Negative Phase contrast - Nikon Optiphot microscope 200X

Bdelloid rotifer by Polarization Microscopy with a full wave plate by Robert Berdan ©

Bdelloid rotifer by Polarization Microscopy with a full wave plate - the muscles show up pink in colour 400X. Nikon Optiphot microscope.

Because few people have heard of rotifers I would like to share some pictures and information about these fascinating organisms. They live in my backyard, roof gutters, bird bath, tree lichen, moss and soil - in fact anywhere there is a temporary pool of water will usually be home to rotifers. They come in a wide variety of shapes and resemble aliens. Some groups of rotifer (Bdelloidea) have no males - only females yet they are able to thrive and evolve in the absence of sex.

Cyrotonia tuba rotifer freshwater by Robert Berdan ©

Side view of a rotifer with DIC microscopy showing a 3D like relief - the head is at the top left (Cyrotonia tuba).

There are three main groups of rotifers: 1) Bdelloidea - they can survive dessication and appear to consist of only females and reproduce asexually via parthenogenesis (unfertilized eggs). 2) Monogononta - they cycle between parthenogenesis and eggs that are fertilized and 3) Seisonidae a family of rotifers found only on the gills of a marine crustacean. I only show examples of rotifers from the first two groups. Below is a diagram of a model rotifer.

Rotifer diagram

Above basic diagram of a female rotifer with the various internal organs labelled. Some rotifers lack some of these parts e.g. toes and show variations in morphology.

Diagram from clker.com

Testudinella patina- nicknamed Turtle Rotifer by Robert Berdan ©

Testudinella patina - nicknamed "Turtle Rotifer" - has a telescoping foot that has contracted into the body, also note the two red eyes at the top. (Monogononta, Gnesiotrocha, Flosculariaceae).

Rotifers have other unusual characteristics. They possess a constant number of cells (900-1000) referred to as eutely. Their cells do not divide after they are born, growth occurs by changes in the size of the cells. Furthermore, most of their tissues are syncytial - that is many of the tissues share nuclei. Some tissue like the nerves and gut epithelium do have individual cells. Their body cavity is called a pseudoceol as it is not lined by an epithelium and functions as a hydrostatic skeleton, respiratory organ and circulatory system.

Finding and Collecting Rotifers

Fish pond for cellecting rotifers by Robert Berdan ©

I collect rotifers and other protists from ponds near my home in Calgary. I use jars attached to a golf ball retriever to reach out into the water and a turkey baster from Walmart to collect sediment from around the edges of the pond as described in books by Tony Pattinson (The Freshwater Microscopist). A pair of rubber boots for wading is helpful.

I try to include some water plants in each jar as that is where I find most of the rotifers. A magnifying lens or stereomicroscope can be helpful to find the rotifers before placing them onto a microscope slide. Sometimes I use a centrifuge to concentrate specimens in a sample of water. When mounting the rotifers one has to be careful not to crush them when placing the overlying coverslip on a microscope slide. Sometimes I will add 4 small drops of vacuum grease (or vaseline) with a syringe on the corners of the coverslip and it press down gently over the sample. The grease helps prevent the coverslip from completely drying down and crushing the rotifers.

Epiphanes clavulata - Large rotifer by Darkfield microscopy by Robert Berdan ©

Large rotifer by Darkfield microscopy found in a local fish pond. Notommata copeus Ehrenberg 1834.

At the anterior end of many rotifers is a corona consisting a cilia which appear to rotate like a wheel resulting in their early name wheel animalcule (Rotifera latin rota - wheel). The cilia appear to rotate and function in locomotion and to draw food (bacteria, small algae, and yeast) into their mouth. The corona can be withdrawn into the animals lorica or shell and some of the rotifers can also move like an inch worm. See my video at the end of my article on Protozoa which shows rotifers crawling like an inch worm.

Lepadella ovalis with egg inside DIC microscopy

Lepadella ovalis with egg inside DIC microscopy. Monogononta, Plioma, Lepadellidae.

Lepadella ovalis by Robert Berdan ©

Lepadella ovalis - perfectly streamlined - DIC microscopy

Lecan sp note the double foot and toes by Robert Berdan ©

Lecan sp note the double foot and toes - head contracted into the lorica (shell). Monogononta, Lecanidae.

Microcodon clavus rotifer by Robert Berdan ©

Unidentified rotifer species (possibly Microcodon clavis) with a single toe and wide ciliated corona.

Monommata arndti has a long foot Monogononta, Ploima, Notommatidae by Robert Berdan ©

Monommata arndti has a long foot Monogononta, Ploima, Notommatidae 200X

Lecane quadridentata rotifer by Robert Berdan ©

Lecane quadridentata (I think it was previously described as Monostyla quadridentata). It is nicknamed the "devil rotifer" because of the horn like projections from the lorica.

Bdelloid Rotifers by Robert Berdan ©

Bdelloid Rotifers - one with the corona beating and the other one with the corona contracted. 200X

Large Bdelloid rotifer found in moss by Robert Berdan ©

Large Bdelloid rotifer found in moss - it appears to have an egg inside - corona retracted.

Euchlanis sp DIC microscopy by Robert Berdan ©

Euchlanis sp DIC microscopy - single red eyespot just barely visible

Euchlanis sp viewed by Dark field microscopy by Robert Berdan ©

Euchlanis sp viewed by Dark field microscopy

Euchlanis sp viewed by Dark field microscopy by Robert Berdan ©

Euchlanis sp viewed by DIC (differential interference contrast) microscopy

Euchlanis sp - some species have a single toe by Robert Berdan ©

Euchlanis sp - have a two toes

Euchlanis sp with head retracted into its lorica by Robert Berdan

Euchlanis sp with head retracted into its lorica

Rotaria neptunia- the most elongate rotifer known by Robert Berdan ©

Rotaria neptunia - the most elongate rotifer known has 3 terminal toes and can extend its foot which "telescopes" increasing its body length almost 3X. Bdelloidea, Philodinidae, Rotoria.

Rotaria neptunia rotifer by Robert Berdan ©

Rotaria neptunia - a young rotifer can be seen inside the mother and can be identified by the extra trophi and red eyes.

Rotaria neptunia - showing 2 eyes and detail of the trophi which has 4 large teeth by Robert Berdan ©

Rotaria neptunia - showing 2 eyes and detail of the trophi which has 4 large teeth. The head and foot are often retractable into the trunk.

Bdelloid rotifer - note the red eyes by Robert Berdan ©

Bdelloid rotifer - note the red eyes

Bdelloid rotifer Philodina roseola by Robert Berdan ©

Bdelloid rotifer Philodina roseola. (Bdelloidea, Philodinida, Philodinidae)

Philodina roseola rotifer by Robert Berdan ©

Philodina roseola swimming - note the two spurs at the posterior end - it is one of the most common species of rotifers. Bdelloidea, Philodinidae. The corona of cilia can provide locomotion or the rotifer can move by creeping like an inch worm. The head (rostrum) and the toes have special adhesive glands that can be used to anchor to the substratum so they can push or pull themselves along.

Large bdelloid rotifer with corona withdrawn and the rostrum by Robert Berdan

Large bdelloid rotifer with corona withdrawn and the rostrum containing the eyes extended

Trophi - are the hard chitinous parts of the masticatory (chewing) apparatus. It is often in motion when observing rotifers and can even be recognized in cysts and dead animals. The shape and organization of the trophi is used to taxonomically. It is situated in the ventral side of the pharynx (tube that extends from the mouth to esophagus) within the mastax which is composed of muscles that move the "jaws".

Bedlloid rotifer stretched out with corona retracted by Robert Berdan ©

Bedlloid rotifer stretched out with corona retracted - note the trophi inside - DIC microscopy.

Bdelloid rotifer by Robert Berdan ©

Bdelloid rotifer - the trophi and its teeth can be clearly seen inside the organism. This rotifer was crawling along like an inch worm. DIC microscopy.

Closeup of a Trophi from a bdelloid rotifer by Robert Berdan ©

Closeup of a Trophi from a bdelloid rotifer showing the chitinous teeth and other parts. Trophi play a role in grabbing prey and chewing food. In live rotifers they can often be seen moving inside the organism. The parts of the trophi are shown above - though a fulcrum is missing in Bedelloid rotifers. The jaws operate like forceps. Trophi attain their size and shape in the fully grown embryo and remain constant during the life of the rotifer. Rotifer biologists can isolate the Trophi by treating the organisms with Chlorox bleach which digests the rest of the organism. There are nine main types of trophi based on their shape and size of the elements. The shape of the trophi is important in rotifer taxonomy. For a detailed description of the various types of trophi see D. Fontaneto and W.H. De Smet (2015).

Euchlanis dilatata species? Side view (Eurotatoria, Plioma, Euchlanidae) by Robert Berdan ©

Euchlanis dilatata species? Side view (Eurotatoria, Plioma, Euchlanidae)

Rotifer releasing an egg (Euchlanis sp?) by Robert Berdan ©

Rotifer releasing an egg (Euchlanis sp?)

Trichocerca sp? This is a small rotifer that is common in pond water by Robert Berdan ©

Trichocerca sp? This is a small rotifer that is common in pond water.

Trichotria sp (Trichotria tetractis?)- note the spur that looks like a shark fin by Robert Berdan ©

Trichotria sp (Trichotria tetractis? )- note the spur that looks like a shark fin. Eurotatoria, Plioma, Trichotriidae.

Lepadella sp of rotifer by Robert Berdan ©Lepadella ovalis - with head withdrawn into the lorica, photo stack.

Large Bdelloid rotifer with young inside by Robert Berdan ©

Large Bdelloid rotifer with young inside - note two trophi inside the animal.

Rotifer Dorsal antenna by Robert Berdan ©

Note the Dorsal antenna which protrudes and retracts like a periscope - it's believed to be sensory in function.

Monogonota rotifer (Polyarthra remata?) by Robert Berdan ©

This Monogonota rotifer (Polyarthra remata?) has feather-like fins - the animal is partly compressed and unfortunately I damaged it when I mounted it.

sessile rotifer Stephanoceros fimbriatus (Monogonota, Gnesiotrocha, Collothecidae) by Robert Berdan ©

This sessile rotifer Stephanoceros fimbriatus (Monogonota, Gnesiotrocha, Collothecidae) was collected in a fish pond and found by itself attached to a branch of Bladderwort (Urtiularia). It was attached to the plant via a flexible retractable stalk. I was able to find it on an algae branch by viewing the algae with a stereoscope and then cutting the branch and putting it on a microscope slide.

Lecane sp rotifer by Phase contrast microscopy by Robert Berdan ©

Rotifer by Phase contrast microscopy (Lapadella ovalis).

Brachionus Rotifers - may be available at your local aquarium or pet store

Brachionus manjavacas rotifers from a Pet store in Calgary - bottle by Robert Berdan ©

Brachionus is a genus of planktonic rotifers occurring in freshwater, alkaline and brackish water. I purchased a bottle of Brachionus manjavacas rotifers from a Pet store in Calgary ($30\bottle - Pisces Exotica Pet Emporium) - they are used to feed fish larva. I found two types of rotifers in this bottle; the one shown below is Brachionus. The lorica (shell) is pear-like shape. Brachionus is a Monogonont rotifer (Rotifera, Monogononta, Euroatoria, Poima, Brachionus sp). I placed a sample of the water in a shallow dish and viewed them under my stereoscope first and then selected them with an eyedropper to photograph with my light microscope. Brachionus sp are also used in toxicology, stress and aging research. Brachionus species can normally reproduce sexually and asexually (cyclical parthenogenesis). This Calgary pet store sourced the rotifers from Sustainable aquatics - for more information see their web site. They recommend storing the Rotifers in the fridge.

Brachionus manjavacas rotifers at low magnification - DIC microscopy by Robert Berdan ©

Two Brachionus manjavacas rotifers at low magnification - DIC microscopy

Brachionus manjavacas photographed using a combination of Rheinberg lighting and DIC microscopy by Robert Berdan ©

Brachionus manjavacas photographed using a combination of Rheinberg lighting and DIC microscopy. Note the red eye at the right.

Brachionus manjavacas head showing ciliated corona by Robert Berdan ©

Brachionus manjavacas head showing ciliated corona, a bit of the red eye spot - photo stack of 5 images.

Brachionus manjavacas foot - rotifer by Robert Berdan ©

Brachionus manjavacas closeup of the foot showing cells (neurons or muscle) attached to the toes. DIC microscopy.

Brachionus manjavacas by Darkfield microscopy by Robert Berdan ©

Brachionus manjavacas by Darkfield microscopy note the red eye

Male Rotifers

Female rotifer Colurella sp (Leadellidae) by Robert Berdan ©

Female rotifer Colurella sp (Leadellidae). Males are rare and much smaller than females and in some groups of rotifers (Bdelloidea) males have never been reported. Males usually only live for a few days and have only one purpose to fertilize eggs - they don't or can't feed. The factors that control the appearance of males in a population is not well understood.

Cysts and anhydrobiosis - surviving dessication

Rotifers viewed with my microscope seem to be able to retract into their shell as soon as water under the coverslip starts to dry up and conversely they come back out within minutes of adding freshwater. The sugar Trehalose has been suggested to play an important role in anhydrobiosis of Tardigrades but it is absent in the Bdelloidea rotifers. Other molecules like heat shock proteins, chaperones (proteins that assist in protein folding), antioxidants etc may be more important. Anhydrobiosis in rotifers requires more research and it may have implications for space travel in the future.

Rotifer Cyst with Trophi visible near the center by Robert Berdan ©

Rotifer Cyst with trophi visible near the center - DIC microscopy

Rotifer cyst by Robert Berdan ©

Rotifer cyst - you can see the Trophi inside the shell and in the photo below the rotifer coming out of the shell. Rotifers will retreat into their lorica or shell when I flatten the coverslip by removing water with a piece of filter paper that I touch to the edge of the coverslip. If I add water to the side of the coverslip - the rotifer appears to rehydrate within a few minutes and they come back out of their "shell".

Rotifer coming out of the cyst by Robert Berdan ©

Rotifer coming out of the cyst within a few minutes of adding fresh pond water

Cyst belonging to a rotifer by Robert Berdan ©

Cyst belonging to a rotifer - the trophi is just visible through the shell. Rotifers can survive dessication in cyst form for long periods of time.

Rotifer cyst, tun or xerosome by Robert Berdan ©

This is appears to be a rotifer tun - similar to the "tuns" formed by water bears and serves the same purpose - to survive dessication. Rotifers can survive for decades in this state and do not age or if they do - they age very slowly. One researcher likens these cysts or tuns to a "time machine". This picture resembles a tun from Macrotrachela quadricornifera Fig. 2 (Ricci and Fontaneto, 2009). Because Tardigrades also exhibit anhydrobiosis and form tuns it has been proposed that rotifer tuns be called a "xerosome" (Wallace et al. 2010) to distinguish them from those produced by Tardigrades.

Classification of Rotifers - Segers (2007)

Domain: Eukaryote (cells with a nuclear membrane)

Kingdom: Animalia

Clade: Platyzoa (monophyletic group in which members are thought to have evolved from a common organism).

Phylum: Rotifera

Class: Pararotatoira - single Family: Seisonidae - marine, obligatory sexual - species

Class: Eurotatoria

Subclass: Bdelloidea - Parthenogenic (develop from eggs without fertilization) - 461      species

Order: Adinetida

Order: Phildinavida

Order: Philodinida

Subclass: Monogononta - Intermittently sexual, but no males have been reported - 1570       species

Superorder: Pseudotrocha

Order: Ploima

Superorder: Gnesitrocha

Order: Flosculariacea

Order: Collothecacea

Trichocerca cylindrica focus stack by DIC microscopy by Robert Berdan ©

Trichocerca cylindrica focus stack by DIC microscopy

Asplanchnopus multiceps by Robert Berdan ©

One of the largest rotifers Asplanchnopus multiceps with two chydorine chydoreds in the gut alonine and Chydorine chydorid (identity of Cladocerans courtsey of Dr. Russell Shiel University of Adelaide). Its transpacent carapace allows you to view the internal organs and cells with DIC. Epiphanes clavulata (Epiphanes: Epiphanidae: Ploima: Pseudotrocha: Monogononta: Eurotatoria)

Rotifer - Platyias quadricornis by Robert Berdan ©

Rotifer - Platyias quadricornis Ventral view of the Lorica - Stack of 15 images DIC microscopy (Monogonota, Pseudotrocha, Plioma, Bradionidae).

Photomicrography

All photographs in this article are of live rotifers collected from fresh water water near my home (except Brachionus sp purchased at a pet store). For details on how I took these pictures please see my article - Tips on How to Take Better Pictures with a Microscope - Photomicrography. I used a Nikon D500 and Nikon D800 cameras, Zeiss Axioscope with DIC, Bright field, and Darkfield lighting, and controlled my cameras with free software Digicam control. Images and video were captured onto an Alienware laptop and processed in Adobe Photoshop. The two biggest challenges is getting the rotifers to hold still and the shallow depth of field that occurs in microscopy at higher magnification. In many instances I stacked 2-12 images to increase the depth of field - for more information on this procedure see my article on focus stacking. The background colours can be changed arbitrarily using a full wave plate with DIC microscopy. Rotifers were isolated from plastic Petri dishes and collected with a glass pipette, plastic eppendorf pipette or a small Irwin loop (handle with a small wire loop) and placed onto microscope slides for photomicrography.

Testudinella patina - Turtle Rotifer DIC microscopy by Robert Berdan

Testudinella patina - Turtle Rotifer DIC microscopy - a wave plate was used to change the background colour.

Summary

In this short introduction to Rotifers I tried to show some of their unusual shapes and features. They can be found in almost any body of freshwater and\or live in the film of water in soil, moss, lichens and bryophytes. The Bdelloids are interesting in that they are able to evolve in the absence of males and may acquire new genes through horizontal gene transfer (from DNA of surrounding bacteria, algae and other organisms). Their ability to survive dessication for decades like the Tardigrades (Water bears), Nematodes and other Protists living in pond water allows them to be found almost everywhere there is water. They play an important role in nutrient cycling and are used in research for toxicity testing and aging research. They are interesting to watch and photograph with a microscope and are found almost everywhere. If you don't own a microscope, no worries just come back and visit my web site as I will be posting more photomicrographs in the future but you can purchase a pretty good used microscope or even a new starter microscope for under $1000. RB

References (most can be found online)

(2017) A. Örstan and M. Plewka. An Introduction to Bdelloid Rotifers and their Study - www.quekett.org/starting/microscopic-life/bdelloid-rotifers

(2015) D. Fontaneto and W.H. De Smet - Chapter 4 Rotifera - In book: Handbook of Zoology, Gastrotricha, Cycloneuralia and Gnathifera. Volume 3, Publisher: de Gruyter Editors: Andreas Schmidt-Rhaesa pp 217- 300 - excellent recent review - download PDF

(2015) T. Pattinson. The Freshwater Microscopist Vol I and II. Blurb books.

(2012) E.F. Wilts, D. Wulfken, W.H. Ahlrichs and P.M. Arbizu. The musculature of Squatinella rostrum (Rotifera: Lepadellidae) as revealed by confocal laser scanning microscopy with additional new data onm its trophi and overall morphology. Acta Zoologica 93: 14-27.

(2010) R.L. Wallace, T. W. Snell and H.A. Smith. Phylum Rotifer Chapt 13 in Thorp and Covich's Freshwater Invertebrates. Academic Press, NW. 3rd edition. pp 225-271.

(2009) C. Ricci and D. Fontaneto. The importance of being a bdelloid: Ecological and evolutionary consequences of dormancy. Italian J. Zoology: 76: 240-249.

M. Plewka (2009) Lepadella ovalis - plingfacory.de

(2007) Segers. Annotated checklist of the rotifers (Phylum Rotifera) with notes on the nomenclature, taxonomy and distribution. Zootaxa 1564: 1-104, - download PDF.

(2006) R. L. Wallace. Rotifers: Exquisite Metazoans. Integ. and Comp. Biol. 42:660-667.

(1995) R.J. Shiel. A guide to identification of Rotifers, Cladocerans and Copepods from Australian inland Waters. Research Guide. Free PDF

(1974) A. Ruttner-Kolisko. Plankton Rotifers Biology and Taxonomy. Stuttgart, Germany.

(1959) W.T. Edmonson (ed) Fresh Water Biology 2nd edition, John Wiley. NY pg 420-507 - read online version free.

Online image based key for Rotifers - cfb.unh.edu/cfbkey/html/rotifers.htm

An Illustraded Key to the Planktonic Rotifers of the Laurentian Great Lakes - free PDF

Rotifer World Catalog - rotifera.hausdernatur.at

Plingfactory - see numerous photomicrographs of rotifers by M. Plewka (In german use Google translator in your browser)

Microscopy from the very beginning - free book produced by Zeiss PDF

Boreal Science\Ward Science - purchase rotifers for study by mail

Quality Microscopes in Calgary - Zeiss dealer sells stereomicroscopes

Macrophotography.net - Forum on macro and photomicrography

Acknowledgements

Note to teachers and students you have permission to use my pictures for teaching or school projects. I appreciate credit and\or link back to my web site if possible. For commercial use of my photos please contact me. Note species were identified using a variety of keys. Please regard species identifications with some reservation as I am not a Rotifer taxonomist just an Rotifer enthusiast. Thank you to Josh Grosse for pointing out some species errors I have made the corrections. I also thank Dr. R. Shiel (Invertebrate biologist) from Australia for pointing out some of my identification errors (rjsheil.com and https://www.adelaide.edu.au/directory/russell.shiel).

Authors Biography & Contact Information

Portrait of Robert BerdanRobert Berdan is a professional nature photographer living in Calgary, AB specializing in nature, wildlife and science photography. Robert retired from Cell\Neurobiology research to take up photography full time years ago. Robert offers photo guiding and private instruction in all aspects of nature photography and Adobe Photoshop training - including photomicrography, macrophotography.

Related Microscopy Articles by Robert Berdan on this web site

Photographing Ciliates

by Dr. Robert Berdan

July 17, 2018

Spirostomum minus (top) and Urocentrum turbo by Robert Berdan ©

Spirostomum minus (top) and Urocentrum turbo (bottom) - both are common ciliates in fresh water. DIC (differential interference microscopy) A micron = 1\1000 of a millimetre.

Introduction to the ciliates

You may have been introduced to Paramecium in biology class, a single celled (unicellular) "simple" ciliate found in pond water. Only ciliates are not simple but some of the most complex cells on the planet. They have an intricate cytoskeleton (support network of microtubules and filamentous fibers), cilia of several different sorts, 2 different types of nuclei and come in a wide variety of shapes and sizes. Ciliates can be found anywhere there is water; in ponds, streams, lakes, oceans, soil and the water in and around plants, mosses and liverworts. It isn't known how many species there are but about 9000 species have been described and estimates suggest there may be as many as 30,000 or more. Most ciliates are microscopic in size, but a few get as large as 4 mm in length (e.g. Stentor).

Cilia are small hair-like structures that cover most ciliates during some stage of their life cycle. Cilia means "eye lash". The organisms may have different sized cilia. Cilia are used for locomotion and also to direct food into their mouth. Cilia may be fused into long sheets (undulating membranes), or arranged as a series of short pennants; they may form movable tufts (cirri), or stiff bristles (setae). However, it's not the presence of cilia that characterize this group, but the presence of two types of nuclei - a macronuculeus and micronucleus.

Spirostomum minus - DIC microscopy by Robert Berdan ©

Spirostomum minus - DIC microscopy

The macronucleus is often large and sometimes is easily seen inside the cells, and it is also polyploid (contains multiple copies of the genes). The function of the macronucleus is to regulate metabolism and day to day functions of the cells. There may be one or more micronuclei that are involved in genetics and exchange of DNA.

Reproduction usually occurs by binary fission across the long axis and they can also undergo conjugation where they exchange genetic material with another ciliate of the same species. Conjugation involves partial fusion of paired cells allowing mutual exchange of genetic material. In syngamy the two cells fuse completely. They can also reproduce using a variety of other methods (see below). After about 200 cell divisions some ciliates show signs of aging and the reorganization of their DNA during conjugation somehow reestablishes their vitality and makes them young again.

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Most ciliates divide by binary fission, but they may multiply using a variety of other methods shown above. Diagram courtesy Wikipedia by Deuterostome.

Paramecium caudatum dividing by Robert Berdan ©

Paramecium caudatum dividing. I usually see ciliates dividing in the evenings. They usually continue to move about during division perhaps to avoid predation.

Ciliate dividing by Robert Berdan ©

Ciliate dividing

scuticociliate Dexiotricha granulosa with ring shaped glycogen granules by Robert Berdan ©

Two scuticociliates Dexiotricha granulosa with ring shaped glycogen granules in the cytoplasm joined together possibly undergoing conjugation. (ID courtesy of Bruce Taylor - YouTube Video).

Two more ciliates that appear to be undergoing conjugation.

Palintomy in Colpoda ciliates DIC microscopy by Robert Berdan ©

Palintomy a process during which a large parental cell undergoes a rapid sequence of repeated divisions without intervening growth. Arrows point to the boundaries between 4 Colpoda ciliates. Several frames were extracted from a movie and focus stacked, DIC microscopy 600X.

Most ciliates ingest food through a cytosome, once ingested food is enclosed in a food vacuole. The digested food contents are released by the ciliates anus which may be well defined (cytoproct). Ciliates also contain one or more contractile vacuoles which functions to remove excess water or ions that flow into the cells by osmosis. In Paramecium you can watch the contractile vacuole expand and contract at regular intervals. The position of the contractile vacuole can be useful in identifying some species.

Spirostomum minus by Robert Berdan ©

Spirostomum minus with adoral zone of membranelles (larger cilia) on the right side of the body extends almost half the body length. 600X DIC microscopy.

Spirostomum minus posterior end and contractile vacuole by Robert Berdan ©

Above, Spirostomum minus posterior end, the contractile vacuole is in the darker region and you can see a spiral pattern on the pellicle made up of cortical granules. 600X DIC microscopy.

The ciliate cortex (outer covering) exhibits features used to characterize and identify different species along with their shape and approximate size. The cortex is often divided into two regions the somatic (body) and the oral regions. The ciliary structure around the oral regions is important in classifying the organisms. An element of the cortex is the Kinetid composed of one or more kinetosomes with their fibrils and cilia. Kineties are simply ciliary rows (kinety is a single row of cilia). Somatic kinetids may have 1, 2 or more Kinetosomes through which the cilia are formed. The presence and distribution of kinetids on the body surface is a characteristic of the taxon.

Phacodinium metchnikoffi a ciliate found in moss by Robert Berdan ©

Streamlined like an alien spaceship this ciliate is able to swim quickly. I found it in moss while searching for water bears (Tardigrades). This ciliate was flattened dorsal - ventrally. Phacodinium metchnikoffi is apparently a rare ciliate (see M. Kruetz and W. Foissner publication page 141 - free PDF with excellent photomicrographs).

Some ciliates lack a cystosome and acquire nutrients at the cell surface by adsorption and pinocytosis (ingestion of small membrane vesicles). Suctorians are a group of ciliates that are sedentary as adults without cilia and ingest food on the tips of long tentacles (see below).

Podophyra fixa - Suctorian by Robert Berdan ©

Above - a Suctorian with long tentacles used to capture prey (Podophyra fixa). Phase Contrast microscopy, Olympus E microscope. These ciliates only have cilia during their early stage. They often reproduce by external budding.

Spathidium spathula by Robert Berdan ©

Spathidium spathula found in moss while searching for water bears, the oral region (top) is conspicuously swollen.

Cilia are not restricted to ciliates, but are found associated with many other animals and in fact cilia are responsible for removing dust and other pathogens from our own lungs. However, in many ciliates, cilia allows them to move about quickly, back up and even spin making photography of these organisms challenging at times. To get sharp pictures I need to use fast shutter speed (1\500 of sec or faster) or trap the animals by removing water from below the overlying coverslip with filter paper (see my article Tips on How to Take Better Pictures with a Microscope). The compression technique seems to work with some of the larger ciliates. Another way to slow ciliates down is to increase the viscosity of the water (e.g. adding methyl cellulose). Gently heating the microscope slide for a few seconds under a flame may also stop or slow them down but often it cooks the organisms and they burst shortly after. It is also possible to use a high speed flash to stop the motion of some ciliates.

Urocentrum turbo (Family Parameciidae) - ciliate by Robert Berdan DIC microscopy ©

Urocentrum turbo (Family Parameciidae) - a fast moving ciliate found in pond water often in association with Paramecium. They spin and move erratically.

The fastest Ciliate on the Planet?

Halteria sp - side view showing some of the long bristle like cirri

Halteria sp - dorsal view looking down showing the adoral zone of membranelles. This organism can move hundreds of times its body length in less then a second and often disappears out of the field of view when observing with a light microscope.

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Diagram of Halteria from C. R. Curds (1982) British and Other Freshwater Ciliated Protozoa. Cambridge University Press. London (page 439).

Halteria is a small but common ciliate found in pond water. What makes this ciliate interesting is that one moment it will be lying still and then appear to jump out of the field or across the slide at very high speed - like jumping to warp drive. A study using high speed digital video recorded the ciliary beating of Halteria grandinell to be between 105 and 260 Hz (cycles per second). These frequencies are the highest observed for cilia and flagella reported to date (2005).

Spirostomum minus and smaller Paramecium caudatum by Robert Berdan ©

Spirostomum minus and smaller Paramecium caudatum by Robert Berdan ©

Above pictures show the giant ciliate Spirostomum minus and smaller Paramecium caudatum.

Identifying different ciliates is challenging because there are so many different shapes and varieties and many of them can move quickly. The taxonomy of these organisms is also changing as more researchers apply molecular biology techniques to analyze similarities and differences.

In this article I show some ciliates that are relatively common. I almost always encounter new ones that I have never seen before in any jar of pond water I collect. The great variety of ciliates intrigues me. I have purchased several books and and guides to help me identify many of the organisms and I also send pictures to a friend and ciliate expert (Bruce Taylor) for verification or correction. However, one doesn't have to be able to identify each species in order to appreciate them.

Ciliates can be found in bodies of water all year long even under the ice. One can also culture ciliates by producing a hayinfusion where one puts hay in water with a small amount of powdered milk, wheat or rice grains (read more on the Microbe hunter). The ciliates feed on the bacteria that in turn feed on the powdered milk or grains. I made several hayinfusions when I was younger when I wanted to view protozoa throughout the winter months. You can also purchase ciliates for classroom or private study e.g. Boreal Science. I purchased some Paramecium and several other invertebrates from Boreal this past February - a small tube is only $12.00. The rest of the year any body of water is likely to have some ciliates in it. You can even collect rain water from your roof to see some ciliates and other protists (see my article Microscopic Life in Ponds and Rainwater). I also use a centrifuge that I purchased on Kijjii to concentrate some of the water samples. Generally I spin the water samples for 2 minutes at 1800g - though often I can find plenty of ciliates and other organisms by sampling the water from a jar and\or including some water plants.

Colpoda cucullus (Class: Colpodea) by Robert Berdan ©

Colpoda cucullus (Class: Colpodea). Ciliate which in well-nourished specimens is crammed with up to 200 compact, 5-8 microns sized food vacuoles. These medium sized ciliates are common and often bean shaped. They are one of the earliest ciliates to appear in a hay infusion. They are frequently found in soil and moss because of their ability to form cysts. They feed primarily on bacteria. Learn more and visit EOL web site for a more detailed description of this species.

Heterotrich ciliate DIC microscopy by Robert Berdan ©

Unidentified medium sized ciliate with membranelles around the anterior end, several large macronuclei and conspicuous contractile vacuole. Heterotrich.

Vorticella or Pseudovorticella is a Peritrich ciliate by Robert Berdan ©

Vorticella or Pseudovorticella is a Peritrich ciliate which attaches to the substratum via a retractable stalk. The stalk can contract quickly and the ciliates are often found in groups attached to underwater plants. The cilia sweep bacteria into their cytosome along with other small organisms like algae - essentially they are filter feeders. The have a large C shaped macronucleus (see more pictures in my article on Protozoa). DIC microscopy - learn more about Vorticella. Note Pseudovorticella has a sort of brickwork pattern, whereas Vorticella has lateral corrugations on its surface.

Peritrichia - epistylid by Robert Berdan ©

Peritrich in which the stalk was short and did not contract like those in Vorticella. Class: Oligohymenophorea; Subclass: Peritrichia - epistylid.

Peritrich - Epistylis sp on broad flat stalk that is not contractile by Robert Berdan ©

Peritrich - Epistylis sp on broad flat stalk that is not contractile.

swarmer (telotroch) phase of a peritrich ciliate by Robert Berdan ©

telotroch phase of a peritrich ciliate by Robert Berdan ©

Above two photos - These are the swarmer (telotroch) phase of a peritrich ciliate - probably Vorticella. When swarming, they shed their stalks, become somewhat cylindrical and develop a wreath of cilia at the posterior. Most peritrichs have a telotroch phase (identified by Bruce Taylor). See video by Bruce Taylor and read additional information about telotrochs on www.microscopy-uk.org.uk.

Stylonchia mytilus by Robert Berdan ©

At first I thought this was Stylonchia mytilus a very common ciliate in pond water and soil. It is has three long cirri at the posterior, and cilia grouped into membranelles alongside the mouth and cirri over the body. However ciliate expert Bruce Taylor suggested that this is probably Tetmemena as three members of Stylonchia were moved to this genus several decades ago.

The easiest way to observe ciliates and other protozoa is to collect water from a pond, ditch, stream edge, lake, estuary, or pour some bottled water or distilled water over some dry moss or soil in a dish and wait an hour then examine some of the water on a microscope slide with a microscope. A simple microscope with brightfield illumination will work fine. I started with a $30 toy microscope. An interest in microscopy lead me into a career in cell biology and nature photography. Microscopes with Phase contrast or Differential Interference will make it easier to see the ciliates as most of the protists are translucent, but any decent microscope with 100-400X magnification will permit you to see and study these organisms. You can also stain the ciliates though this usually kills them and you don't get to observe their interesting behaviour - for more information on specimen preparation see the free PDF - Protocols in Protozoology.

Hypotrichs possess compound ciliary organelles called "cirri," which are made up of thick tufts of cilia, sparsely distributed on the ventral surface of the cell by Robert Berdan ©

Hypotrich - unidentified ciliate. Hypotrichs possess compound ciliary organelles called "cirri," which are made up of thick tufts of cilia, sparsely distributed on the ventral surface of the cell.

Unidentified ciliate with endosymbiotic algae and single large Macronucleus by Robert Berdan ©

Unidentified ciliate with endosymbiotic algae and single large Macronucleus by Robert Berdan ©

Above two photos of unidentified ciliate with endosymbiotic algae and single large Macronucleus. Some ciliates ingest green algae (Chlorella sp) or acquire them from previous generations. These algae are not digested but form a symbiotic relationship with their host. The algae share sugars they produce via photosynthesis with their host and the host in turn provides them with some protection and nutrients. It is not fully understood why some ingested algae are not digested and how the algae are able to communicate with their host to release sugars to them. Symbiotic algae may be passed down through the generations, and can be closely integrated with the host cell and may even be retained in cyst form. In laboratory conditions, some ciliates can be stripped of their symbionts and reinfected with new ones, but it is not known how often this occurs in nature. Phylogenetic analysis shows that the strains of Chlorella in a variety of ciliates are related to one another and are distinct from "wild" chlorellae (Bruce Taylor personal communication - see this reference for additional information).

Stentor polymorphus with endosymbiotic algae by Robert Berdan ©

Stentor polymorphus with endosymbiotic algae inside. Bright field microscopy.

Ciliate filled with green algae by Robert Berdan ©

Ciliate filled with green algae (endosymbiotic) - possibly Holophyra ovum (suggested ID by Bruce Taylor).

Trachelius ovum by Robert Berdan ©

Trachelius ovum- this unusual ciliate would eject parts of its cellular contents when trapped by the coverslip in order to become a smaller organism. It's body appears to be very fragile and this may be a mechanism to avoid predators. Below you can the same organism after it shed its internal components. Mouth is round, located at the base of a short proboscis.

Trachelius ovum by Robert Berdan ©

Trachelius ovum - next to the body parts it shed. This unusual behaviour has been observed before in Trachelius and reported in J. of Natural History by S. G. Foulke 2009 - describing observations by Mr. Charles Robertson in 1867. Also see observations by C. Gegenbaur (1857).

Trachelius ovum by Robert Berdan ©

Trachelius ovum - after it expelled its body parts.

Trachelius ovum by Robert Berdan -

Flattened Trachelius ovum - sometimes under the pressure of the coverslip this organism would just explode into pieces.

Nassophorean Nassula ornata - mouth leading to palisade of rods or nematodesmata by Robert Berdan ©

Nassophorean Nassula ornata - its mouth leads to palisade of rods or nematodesmata seen inside the cell at the upper right (bright white area). Body ovoid and uniformly ciliated with a single macronucleus (white circle). They feed on blue-green algae and as the algae are broken down they can take on a variety of bright colours. Class: Nassophorea, Order Nassulida, Family: Nassulidae. Learn more and view videos of this microorganism.

Nassula ornata - ciliate with a single strand of blue-green algae by Robert Berdan ©

Nassula ornata - ciliate with a single strand of blue-green algae (cyanobacteria - procaryote which are cells with no nuclear membrane) strand visible inside on the right (Anabaena sp).

Lembadion sp. ciliate by Robert Berdan ©

Oral area seems to comprise more then 2\3 of the ventral surface. Lembadion lucens. Watch YouTube video of this ciliate.

Frontonia atra ciliate by Robert Berdan ©

Frontonia atra with dark pigment granules. I thought the dark granules might be bacteria living inside but they may simply be dark pigment granules. Ciliates in general have been found to host 60 different species of Bacteria.

You can stain ciliates with methylene blue, neutral red or Lugol's iodine, though this can or will kill them. Also you can use a technique called Darkfield microscopy which presents the ciliates against a black background (see above Nassula sp) and the organisms tend to light up white. This technique can be mimicked by putting a coin on the light source or under the condenser on a filter. Oblique illumination can be created by putting the condenser filter holder partially in front of the light source and this will creates a three dimensional like appearance of the specimens that resembles DIC microscopy. Of course you will need some glass microscope slides, coverslips and an eye dropper to put a drop of pond water on the slide for viewing.

Ciliate predation DIC microscopy by Robert Berdan ©

Above one ciliate appears to be devouring another. I watched them for 45 min as they struggled often shaking violently as one tried to escape.

Cysts

Of the thousands of ciliate species known so far only one, Balantidium coli, is known to cause disease in humans. It's regular host is pigs and infection can occur by ingestion of water contaminated with cysts from this ciliate. Many freshwater ciliates, protozoans and other invertebrates are able to survive dessication by forming cysts. I see a lot of cysts in my pond samples but it's difficult to identify which group of organisms the cysts belong to except perhaps some of the cysts of rotifers were I can view their mastax (jaws) through the cyst enclosure.

Freshwater cysts by Robert Berdan ©

Above is just one of hundreds of different unidentified cysts or eggs that I have seen in pond water. Cysts allow many microorganisms to survive dessication, but except for some rotifer and tardigrade cysts they are difficult to identify which organisms they belong to.

Lacrymaria olor a ciliate with long extensible neck by Robert Berdan

Lacrymaria olor a ciliate with long extensible "neck". This organism is sometimes referred to as "Tear of a swan". This ciliate usually has two macronuclei and one micronucleus. The body cilia are arranged in a spiral (see below). It has two contractile vacuoles one at each of its body and its neck can expand or shrink back into its body. (Class: Litostomatea, Family: Lacrymariidae).

Lacrymaria olor contracted showing its great flexibility by Robert Berdan ©

Lacrymaria olor contracted showing its flexibility and large oval macronucleus.

Lacrymaria olor DIC microscopy by Robert Berdan ©

Lacrymaria olor showing macronucleus about 600X DIC microscopy

Paramecium caudatum DIC microscopy by Robert Berdan ©

Paramecium caudatum DIC microscopy. I focused on the outer pellicle.

Unknown ciliate by Robert Berdan ©

Unknown ciliate species? At the top left in the background of the picture are Spirillum "w-shaped" bacteria. The large coloured vacuoles in this ciliate have collected at the "bottom" of this specimen.

Loxophyllum helus is a common elongated ciliate by Robert Berdan ©

Loxophyllum helus is a common elongated ciliate with a neck region and rounded tail, two ovoid macronuclei (just visible inside near the center) and a single contractile vacuole (not visible). The ciliate can be up to 160 microns long.

Loxodes rostrum ciliate by Robert Berdan ©

Loxodes rostrum The cytoplasm in this ciliate is highly vacuolated and it appears to have "beak" shape at the anterior end. There is a small diatom that can also be seen inside near the center. Loxodes belongs to the group of Karyorelictea where the macronucleus does not divide. Loxodes in greek means "oblique, tilted". More photos and information about Loxodes on Pling factory.

Haptorid ciliate by Robert Berdan ©

Unidentified ciliate with moniliform macronucleus (beads on a string) and two contractile vacuoles (dark circles), no endosymbiotic algae - possibly a lisostomatean (e.g. haptorid).

Euplotes sp Ciliate by Robert Berdan ©

Euplotes sp?

Ciliate - spindle shaped hypotrich possibly contracted Stichotricha or Stongylidium (ID suggested by Bruce Taylor)

Ciliate with an adoral zone of membranelles, it appears to be slightly flattened by the coverslip.

Coleps hirtus by Robert Berdan ©

Coleps hirtus has an elaborate ornamentation of the ectoplasmic plates which make up its test (shell). These plates are located inside alveolar vesicles of the cell cortex and contain calcium carbonate plates. DIC microscopy read more.

Coleps hirtus Ciliate by Robert Berdan ©

Coleps hirtus Darkfield microscopy. Coleps feeds on bacteria, algae and flagellates. It uses toxicysts, which are organelles which contain a toxin to stun or kill its prey.

Classification of ciliates (according to Wikipedia)

Domain: Eukaryote (cells with a nuclear membrane) - others include: Procaryotes, Archaea, - Viruses and Prions are currently being considered.

Kingdom: Chromista

Phylum: Ciliophora - protozoans with cilia, 2 types of nuclei (>3500 species)

Subphylum: Postciliodesmataphora - share stacks of postciliary microtubular ribbons associated with somatic kinetosomes, and called postciliodesmata

Class: Heterotrichaea - adoral zone of membranelles macro nuclei divide via extra macronuclear microtubules. e.g. Stentor

Class: Karyorelictea - most are marine except Loxodes, alveoli absent in most

Subphylum: Intramacronucleata - dividing macronucleus that relies on intramacronuclear microtubules

Class: Armophorea - small, aneaerobic ciliates - e.g. see EOL website

Class: Listomatea - e.g. Lacrymaria olor and human parasite Balantidium coli

Class: Colpodea - e.g. Colpod sp. small bean shaped ciliate with uniform cilia

Class: Nassophorea - mouth leading to palisade of rods or nematodesmata

Class: Phyllopharyngea - in some only young have cilia e.g. chonotrics and suctoria

Class: Prostomatea - e.g. Coleps - charateristics see EOL website

Class: Plagiopylea - ciliates common in anaerobic habitats

Class: Olighymenophorea - ventral groove leads to cytosome e.g. Paramecium

Class: Protocurziea - see examples - ancestral form of ciliate?

Class: Spirotreachea - - prominent oral cilia e.g. Euplotes

Class: Cariotrichea - only one species Cariacothrix caudata from Venezuela

Subphylum: Mesodiniea - new group of cliates - more information (for Geeks only).

Spirostomum minus in a contracted state by Robert Berdan ©

Spirostomum minus in a contracted state. The contractile vacuole can be seen on the left in the posterior end. The zone of membranelles on the top right takes up about half the body length.

Photomicrography

For details on how I took these pictures please see my article - Tips on How to Take Better Pictures with a Microscope - Photomicrography. I used a Nikon D500 and Nikon D800 cameras, Zeiss Axioscope with DIC, Bright field, and Darkfield lighting, and controlled my cameras with free software Digicam control. Images were captured onto an Alienware laptop and processed in Adobe Photoshop. In many instances I needed to stack 2-12 images to increase the depth of field - for more information on this procedure see my article on focus stacking.

Summary

Ciliates are among the most complex and diverse unicellular organisms on the planet that form an important component of aquatic ecosystems acting as predators and providing nutrition for organisms at higher trophic levels. Ciliates are also important in the treatment of sewage water and water purification (Madoni 2011). My goal in this article was to share a small selection of photomicrographs and some interesting bits of information about these organisms and hope that it might inspire you to learn more about them.

Online References most or all the references can be found by a Google search

(2016) F. Gao et al. The All-Data-Based Evolutionary Hypothesis of ciliated Protists with a Revised Classification of the Phylum Ciliophora (Eukaryota, Alveolata). Nature scientific reports

(2016) First Record of Two Spirostomum Species of ciliates from Korea - download PDF.

(2016) T. Pattinson. The Freswater Microscopist - Part 2. Available on Blurb.com

(2015) T. Pattinson The Freshwater Microscopist. Available on Blurb.com

(2014) S. I. Fokin & V. Sera. The Hidden Biodiversity of ciliate-Endosymbionts Systems. Mini Review SciMedCentral - download PDF.

(2013) Morphology and 18S rDNA gene sequence of Spirostomum minus and Spirostomum terres from Rio de Janeiro, Brazil - Zoologia 30: 72-79 - download PDF.

(2012) C. Shao et. al. A redescription of the oxytrichid Tetmemena pustulata.... European J. Protistology. 49:272-282.

(2011) P. Madoni. Protozoa in wastewater treatment processess: A minireview. Italian. Journ. Zool. 78: 3-11.

(2007) D. H. Lynn The ciliated Protozoa. Springer Verlag.

(2007) W. Foissner, A. Chao, Laura A. Katz journal Biodiversity and Conservation, Volume 17, No 2, 345–363 - download PDF

(2004) N. G. Senler & I. Yildiz. Faunistic and Morphological Studies on ciliates from a Small Pond, with Responses of ciliate Populations to Changing Environmental Conditions - download PDF.

(2000) Illustrated guide to the Protozoa 2nd edition Society of Protozoologists. Allen Press, USA available on Amazon.com most recent Key to ciliates - check your library - excellent ref book.

(1999) W. Foissner, H. Berger and I. Schumberg. Identification and Ecology of Limnetic Plankton ciliates. Bavarian State Office for Water Management. 798 pages - download free ebook PDF

(1994) W. Foissner and S. Wölfl Revision of the genus Stentor Oken (Protozoa, Ciliophora) and description of S. araucanus from South American lakes. J. Plankton Res. 16: 225-289 - includes key to Stentors - PDF (see Dr. Foissner's other publications on his web site)

(1982) C. R. Curds British and Other Freshwater Ciliated Protozoa. Cambridge University Press.

(1972) H. Bick. Ciliated Protozoa World Health Organization, Geneva - free Ebook PDF

(1959) W.T. Edmondson Fresh Water Biology 2nd Ed. John Wiley, NY (Ward Whipple) - Keys to freshwater invertebrates (out of date but excellent illustrations). 1141 pages - Download PDF

(1953) W.J. Garnett Freshwater Microscopy. Constable & Co. Ltd London - Amazon.com $54.

Ciliates general reference - Wikipedia

Tear of a Swan - Lacrymaria olor - www.microscopy-uk.org

Paramecium (1985) ed H. D. Gortz Springer Verlag, NY

The Biology of Stentor (1961) Vance Tartar, Pergamon Press, NY

Freshwater Invertebrates - Ecology and General Biology (2010) eds J.H. Thorp & D.C.Rogers, Academic Press,NY - Excellent reference book - can purchase book from Elsevier

Pling Factory - In German use Google translation - Loxodes rostrum pictures and others

Microscopy from the very beginning - free book produced by Zeiss PDF

Boreal Science\Ward Science - can purchase some pond organisms

Quality Microscopes in Calgary - Zeiss dealer sells stereomicroscopes

Macrophotography.net - Forum on macro and photomicrography

You may have been introduced to Paramecium in biology class, a single celled (unicellular) "simple" ciliate found in pond water. Only ciliates are not simple but some of the most complex cells on the planet. They have an intricate cytoskeleton (support network of microtubules and filamentous fibers), cilia of several different sorts, 2 different types of nuclei and come in a wide variety of shapes and sizes. Ciliates can be found anywhere there is water; in ponds, streams, lakes, oceans, soil and the water in and around plants, mosses and liverworts. It isn't known how many species there are but about 9000 species have been described and estimates suggest there may be as many as 30,000 or more. Most ciliates are microscopic in size, but a few get as large as 4 mm in length (e.g. Stentor).Cilia are small hair-like structures that cover most ciliates during some stage of their life cycle. Cilia means "eye lash". The organisms may have different sized cilia. Cilia are used for locomotion and also to direct food into their mouth. Cilia may be fused into long sheets (undulating membranes), or arranged as a series of short pennants; they may form movable tufts (cirri), or stiff bristles (setae). However, it's not the presence of cilia that characterize this group, but the presence of two types of nuclei - a macronuculeus and micronucleus.

Spirostomum minus - DIC microscopy by Robert Berdan ©

Spirostomum minus - DIC microscopy

The macronucleus is often large and sometimes is easily seen inside the cells, and it is also polyploid (contains multiple copies of the genes). The function of the macronucleus is to regulate metabolism and day to day functions of the cells. There may be one or more micronuclei that are involved in genetics and exchange of DNA.

Reproduction usually occurs by binary fission across the long axis and they can also undergo conjugation where they exchange genetic material with another ciliate of the same species. Conjugation involves partial fusion of paired cells allowing mutual exchange of genetic material. In syngamy the two cells fuse completely. They can also reproduce using a variety of other methods (see below). After about 200 cell divisions some ciliates show signs of aging and the reorganization of their DNA during conjugation somehow reestablishes their vitality and makes them young again.

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Most ciliates divide by binary fission, but they may multiply using a variety of other methods shown above. Diagram courtesy Wikipedia by Deuterostome.

Paramecium caudatum dividing by Robert Berdan ©

Paramecium caudatum dividing. I usually see ciliates dividing in the evenings. They usually continue to move about during division perhaps to avoid predation.

Ciliate dividing by Robert Berdan ©

Ciliate dividing

scuticociliate Dexiotricha granulosa with ring shaped glycogen granules by Robert Berdan ©

Two scuticociliates Dexiotricha granulosa with ring shaped glycogen granules in the cytoplasm joined together possibly undergoing conjugation. (ID courtesy of Bruce Taylor - YouTube Video).

Two more ciliates that appear to be undergoing conjugation.

Palintomy in Colpoda ciliates DIC microscopy by Robert Berdan ©

Palintomy a process during which a large parental cell undergoes a rapid sequence of repeated divisions without intervening growth. Arrows point to the boundaries between 4 Colpoda ciliates. Several frames were extracted from a movie and focus stacked, DIC microscopy 600X.

Most ciliates ingest food through a cytosome, once ingested food is enclosed in a food vacuole. The digested food contents are released by the ciliates anus which may be well defined (cytoproct). Ciliates also contain one or more contractile vacuoles which functions to remove excess water or ions that flow into the cells by osmosis. In Paramecium you can watch the contractile vacuole expand and contract at regular intervals. The position of the contractile vacuole can be useful in identifying some species.

Spirostomum minus by Robert Berdan ©

Spirostomum minus with adoral zone of membranelles (larger cilia) on the right side of the body extends almost half the body length. 600X DIC microscopy.

Spirostomum minus posterior end and contractile vacuole by Robert Berdan ©

Above, Spirostomum minus posterior end, the contractile vacuole is in the darker region and you can see a spiral pattern on the pellicle made up of cortical granules. 600X DIC microscopy.

The ciliate cortex (outer covering) exhibits features used to characterize and identify different species along with their shape and approximate size. The cortex is often divided into two regions the somatic (body) and the oral regions. The ciliary structure around the oral regions is important in classifying the organisms. An element of the cortex is the Kinetid composed of one or more kinetosomes with their fibrils and cilia. Kineties are simply ciliary rows (kinety is a single row of cilia). Somatic kinetids may have 1, 2 or more Kinetosomes through which the cilia are formed. The presence and distribution of kinetids on the body surface is a characteristic of the taxon.

Phacodinium metchnikoffi a ciliate found in moss by Robert Berdan ©

Streamlined like an alien spaceship this ciliate is able to swim quickly. I found it in moss while searching for water bears (Tardigrades). This ciliate was flattened dorsal - ventrally. Phacodinium metchnikoffi is apparently a rare ciliate (see M. Kruetz and W. Foissner publication page 141 - free PDF with excellent photomicrographs).

Some ciliates lack a cystosome and acquire nutrients at the cell surface by adsorption and pinocytosis (ingestion of small membrane vesicles). Suctorians are a group of ciliates that are sedentary as adults without cilia and ingest food on the tips of long tentacles (see below).

Podophyra fixa - Suctorian by Robert Berdan ©

Above - a Suctorian with long tentacles used to capture prey (Podophyra fixa). Phase Contrast microscopy, Olympus E microscope. These ciliates only have cilia during their early stage. They often reproduce by external budding.

Spathidium spathula by Robert Berdan ©

Spathidium spathula found in moss while searching for water bears, the oral region (top) is conspicuously swollen.

Cilia are not restricted to ciliates, but are found associated with many other animals and in fact cilia are responsible for removing dust and other pathogens from our own lungs. However, in many ciliates, cilia allows them to move about quickly, back up and even spin making photography of these organisms challenging at times. To get sharp pictures I need to use fast shutter speed (1\500 of sec or faster) or trap the animals by removing water from below the overlying coverslip with filter paper (see my article Tips on How to Take Better Pictures with a Microscope). The compression technique seems to work with some of the larger ciliates. Another way to slow ciliates down is to increase the viscosity of the water (e.g. adding methyl cellulose). Gently heating the microscope slide for a few seconds under a flame may also stop or slow them down but often it cooks the organisms and they burst shortly after. It is also possible to use a high speed flash to stop the motion of some ciliates.

Urocentrum turbo (Family Parameciidae) - ciliate by Robert Berdan DIC microscopy ©

Urocentrum turbo (Family Parameciidae) - a fast moving ciliate found in pond water often in association with Paramecium. They spin and move erratically.

The fastest Ciliate on the Planet?

Halteria sp - side view showing some of the long bristle like cirri

Halteria sp - dorsal view looking down showing the adoral zone of membranelles. This organism can move hundreds of times its body length in less then a second and often disappears out of the field of view when observing with a light microscope.

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Diagram of Halteria from C. R. Curds (1982) British and Other Freshwater Ciliated Protozoa. Cambridge University Press. London (page 439).

Halteria is a small but common ciliate found in pond water. What makes this ciliate interesting is that one moment it will be lying still and then appear to jump out of the field or across the slide at very high speed - like jumping to warp drive. A study using high speed digital video recorded the ciliary beating of Halteria grandinell to be between 105 and 260 Hz (cycles per second). These frequencies are the highest observed for cilia and flagella reported to date (2005).

Spirostomum minus and smaller Paramecium caudatum by Robert Berdan ©

Spirostomum minus and smaller Paramecium caudatum by Robert Berdan ©

Above pictures show the giant ciliate Spirostomum minus and smaller Paramecium caudatum.

Identifying different ciliates is challenging because there are so many different shapes and varieties and many of them can move quickly. The taxonomy of these organisms is also changing as more researchers apply molecular biology techniques to analyze similarities and differences.

In this article I show some ciliates that are relatively common. I almost always encounter new ones that I have never seen before in any jar of pond water I collect. The great variety of ciliates intrigues me. I have purchased several books and and guides to help me identify many of the organisms and I also send pictures to a friend and ciliate expert (Bruce Taylor) for verification or correction. However, one doesn't have to be able to identify each species in order to appreciate them.

Ciliates can be found in bodies of water all year long even under the ice. One can also culture ciliates by producing a hayinfusion where one puts hay in water with a small amount of powdered milk, wheat or rice grains (read more on the Microbe hunter). The ciliates feed on the bacteria that in turn feed on the powdered milk or grains. I made several hayinfusions when I was younger when I wanted to view protozoa throughout the winter months. You can also purchase ciliates for classroom or private study e.g. Boreal Science. I purchased some Paramecium and several other invertebrates from Boreal this past February - a small tube is only $12.00. The rest of the year any body of water is likely to have some ciliates in it. You can even collect rain water from your roof to see some ciliates and other protists (see my article Microscopic Life in Ponds and Rainwater). I also use a centrifuge that I purchased on Kijjii to concentrate some of the water samples. Generally I spin the water samples for 2 minutes at 1800g - though often I can find plenty of ciliates and other organisms by sampling the water from a jar and\or including some water plants.

Colpoda cucullus (Class: Colpodea) by Robert Berdan ©

Colpoda cucullus (Class: Colpodea). Ciliate which in well-nourished specimens is crammed with up to 200 compact, 5-8 microns sized food vacuoles. These medium sized ciliates are common and often bean shaped. They are one of the earliest ciliates to appear in a hay infusion. They are frequently found in soil and moss because of their ability to form cysts. They feed primarily on bacteria. Learn more and visit EOL web site for a more detailed description of this species.

Heterotrich ciliate DIC microscopy by Robert Berdan ©

Unidentified medium sized ciliate with membranelles around the anterior end, several large macronuclei and conspicuous contractile vacuole. Heterotrich.

Vorticella or Pseudovorticella is a Peritrich ciliate by Robert Berdan ©

Vorticella or Pseudovorticella is a Peritrich ciliate which attaches to the substratum via a retractable stalk. The stalk can contract quickly and the ciliates are often found in groups attached to underwater plants. The cilia sweep bacteria into their cytosome along with other small organisms like algae - essentially they are filter feeders. The have a large C shaped macronucleus (see more pictures in my article on Protozoa). DIC microscopy - learn more about Vorticella. Note Pseudovorticella has a sort of brickwork pattern, whereas Vorticella has lateral corrugations on its surface.

Peritrichia - epistylid by Robert Berdan ©

Peritrich in which the stalk was short and did not contract like those in Vorticella. Class: Oligohymenophorea; Subclass: Peritrichia - epistylid.

Peritrich - Epistylis sp on broad flat stalk that is not contractile by Robert Berdan ©

Peritrich - Epistylis sp on broad flat stalk that is not contractile.

swarmer (telotroch) phase of a peritrich ciliate by Robert Berdan ©

telotroch phase of a peritrich ciliate by Robert Berdan ©

Above two photos - These are the swarmer (telotroch) phase of a peritrich ciliate - probably Vorticella. When swarming, they shed their stalks, become somewhat cylindrical and develop a wreath of cilia at the posterior. Most peritrichs have a telotroch phase (identified by Bruce Taylor). See video by Bruce Taylor and read additional information about telotrochs on www.microscopy-uk.org.uk.

Stylonchia mytilus by Robert Berdan ©

At first I thought this was Stylonchia mytilus a very common ciliate in pond water and soil. It is has three long cirri at the posterior, and cilia grouped into membranelles alongside the mouth and cirri over the body. However ciliate expert Bruce Taylor suggested that this is probably Tetmemena as three members of Stylonchia were moved to this genus several decades ago.

The easiest way to observe ciliates and other protozoa is to collect water from a pond, ditch, stream edge, lake, estuary, or pour some bottled water or distilled water over some dry moss or soil in a dish and wait an hour then examine some of the water on a microscope slide with a microscope. A simple microscope with brightfield illumination will work fine. I started with a $30 toy microscope. An interest in microscopy lead me into a career in cell biology and nature photography. Microscopes with Phase contrast or Differential Interference will make it easier to see the ciliates as most of the protists are translucent, but any decent microscope with 100-400X magnification will permit you to see and study these organisms. You can also stain the ciliates though this usually kills them and you don't get to observe their interesting behaviour - for more information on specimen preparation see the free PDF - Protocols in Protozoology.

Hypotrichs possess compound ciliary organelles called "cirri," which are made up of thick tufts of cilia, sparsely distributed on the ventral surface of the cell by Robert Berdan ©

Hypotrich - unidentified ciliate. Hypotrichs possess compound ciliary organelles called "cirri," which are made up of thick tufts of cilia, sparsely distributed on the ventral surface of the cell.

Unidentified ciliate with endosymbiotic algae and single large Macronucleus by Robert Berdan ©

Unidentified ciliate with endosymbiotic algae and single large Macronucleus by Robert Berdan ©

Above two photos of unidentified ciliate with endosymbiotic algae and single large Macronucleus. Some ciliates ingest green algae (Chlorella sp) or acquire them from previous generations. These algae are not digested but form a symbiotic relationship with their host. The algae share sugars they produce via photosynthesis with their host and the host in turn provides them with some protection and nutrients. It is not fully understood why some ingested algae are not digested and how the algae are able to communicate with their host to release sugars to them. Symbiotic algae may be passed down through the generations, and can be closely integrated with the host cell and may even be retained in cyst form. In laboratory conditions, some ciliates can be stripped of their symbionts and reinfected with new ones, but it is not known how often this occurs in nature. Phylogenetic analysis shows that the strains of Chlorella in a variety of ciliates are related to one another and are distinct from "wild" chlorellae (Bruce Taylor personal communication - see this reference for additional information).

Stentor polymorphus with endosymbiotic algae by Robert Berdan ©

Stentor polymorphus with endosymbiotic algae inside. Bright field microscopy.

Ciliate filled with green algae by Robert Berdan ©

Ciliate filled with green algae (endosymbiotic) - possibly Holophyra ovum (suggested ID by Bruce Taylor).

Trachelius ovum by Robert Berdan ©

Trachelius ovum- this unusual ciliate would eject parts of its cellular contents when trapped by the coverslip in order to become a smaller organism. It's body appears to be very fragile and this may be a mechanism to avoid predators. Below you can the same organism after it shed its internal components. Mouth is round, located at the base of a short proboscis.

Trachelius ovum by Robert Berdan ©

Trachelius ovum - next to the body parts it shed. This unusual behaviour has been observed before in Trachelius and reported in J. of Natural History by S. G. Foulke 2009 - describing observations by Mr. Charles Robertson in 1867. Also see observations by C. Gegenbaur (1857).

Trachelius ovum by Robert Berdan ©

Trachelius ovum - after it expelled its body parts.

Trachelius ovum by Robert Berdan -

Flattened Trachelius ovum - sometimes under the pressure of the coverslip this organism would just explode into pieces.

Nassophorean Nassula ornata - mouth leading to palisade of rods or nematodesmata by Robert Berdan ©

Nassophorean Nassula ornata - its mouth leads to palisade of rods or nematodesmata seen inside the cell at the upper right (bright white area). Body ovoid and uniformly ciliated with a single macronucleus (white circle). They feed on blue-green algae and as the algae are broken down they can take on a variety of bright colours. Class: Nassophorea, Order Nassulida, Family: Nassulidae. Learn more and view videos of this microorganism.

Nassula ornata - ciliate with a single strand of blue-green algae by Robert Berdan ©

Nassula ornata - ciliate with a single strand of blue-green algae (cyanobacteria - procaryote which are cells with no nuclear membrane) strand visible inside on the right (Anabaena sp).

Lembadion sp. ciliate by Robert Berdan ©

Oral area seems to comprise more then 2\3 of the ventral surface. Lembadion lucens. Watch YouTube video of this ciliate.

Frontonia atra ciliate by Robert Berdan ©

Frontonia atra with dark pigment granules. I thought the dark granules might be bacteria living inside but they may simply be dark pigment granules. Ciliates in general have been found to host 60 different species of Bacteria.

You can stain ciliates with methylene blue, neutral red or Lugol's iodine, though this can or will kill them. Also you can use a technique called Darkfield microscopy which presents the ciliates against a black background (see above Nassula sp) and the organisms tend to light up white. This technique can be mimicked by putting a coin on the light source or under the condenser on a filter. Oblique illumination can be created by putting the condenser filter holder partially in front of the light source and this will creates a three dimensional like appearance of the specimens that resembles DIC microscopy. Of course you will need some glass microscope slides, coverslips and an eye dropper to put a drop of pond water on the slide for viewing.

Ciliate predation DIC microscopy by Robert Berdan ©

Above one ciliate appears to be devouring another. I watched them for 45 min as they struggled often shaking violently as one tried to escape.

Cysts

Of the thousands of ciliate species known so far only one, Balantidium coli, is known to cause disease in humans. It's regular host is pigs and infection can occur by ingestion of water contaminated with cysts from this ciliate. Many freshwater ciliates, protozoans and other invertebrates are able to survive dessication by forming cysts. I see a lot of cysts in my pond samples but it's difficult to identify which group of organisms the cysts belong to except perhaps some of the cysts of rotifers were I can view their mastax (jaws) through the cyst enclosure.

Freshwater cysts by Robert Berdan ©

Above is just one of hundreds of different unidentified cysts or eggs that I have seen in pond water. Cysts allow many microorganisms to survive dessication, but except for some rotifer and tardigrade cysts they are difficult to identify which organisms they belong to.

Lacrymaria olor a ciliate with long extensible neck by Robert Berdan

Lacrymaria olor a ciliate with long extensible "neck". This organism is sometimes referred to as "Tear of a swan". This ciliate usually has two macronuclei and one micronucleus. The body cilia are arranged in a spiral (see below). It has two contractile vacuoles one at each of its body and its neck can expand or shrink back into its body. (Class: Litostomatea, Family: Lacrymariidae).

Lacrymaria olor contracted showing its great flexibility by Robert Berdan ©

Lacrymaria olor contracted showing its flexibility and large oval macronucleus.

Lacrymaria olor DIC microscopy by Robert Berdan ©

Lacrymaria olor showing macronucleus about 600X DIC microscopy

Paramecium caudatum DIC microscopy by Robert Berdan ©

Paramecium caudatum DIC microscopy. I focused on the outer pellicle.

Unknown ciliate by Robert Berdan ©

Unknown ciliate species? At the top left in the background of the picture are Spirillum "w-shaped" bacteria. The large coloured vacuoles in this ciliate have collected at the "bottom" of this specimen.

Loxophyllum helus is a common elongated ciliate by Robert Berdan ©

Loxophyllum helus is a common elongated ciliate with a neck region and rounded tail, two ovoid macronuclei (just visible inside near the center) and a single contractile vacuole (not visible). The ciliate can be up to 160 microns long.

Loxodes rostrum ciliate by Robert Berdan ©

Loxodes rostrum The cytoplasm in this ciliate is highly vacuolated and it appears to have "beak" shape at the anterior end. There is a small diatom that can also be seen inside near the center. Loxodes belongs to the group of Karyorelictea where the macronucleus does not divide. Loxodes in greek means "oblique, tilted". More photos and information about Loxodes on Pling factory.

Haptorid ciliate by Robert Berdan ©

Unidentified ciliate with moniliform macronucleus (beads on a string) and two contractile vacuoles (dark circles), no endosymbiotic algae - possibly a lisostomatean (e.g. haptorid).

Euplotes sp Ciliate by Robert Berdan ©

Euplotes sp?

Ciliate - spindle shaped hypotrich possibly contracted Stichotricha or Stongylidium (ID suggested by Bruce Taylor)

Ciliate with an adoral zone of membranelles, it appears to be slightly flattened by the coverslip.

Coleps hirtus by Robert Berdan ©

Coleps hirtus has an elaborate ornamentation of the ectoplasmic plates which make up its test (shell). These plates are located inside alveolar vesicles of the cell cortex and contain calcium carbonate plates. DIC microscopy read more.

Coleps hirtus Ciliate by Robert Berdan ©

Coleps hirtus Darkfield microscopy. Coleps feeds on bacteria, algae and flagellates. It uses toxicysts, which are organelles which contain a toxin to stun or kill its prey.

Classification of ciliates (according to Wikipedia)

Domain: Eukaryote (cells with a nuclear membrane) - others include: Procaryotes, Archaea, - Viruses and Prions are currently being considered.

Kingdom: Chromista

Phylum: Ciliophora - protozoans with cilia, 2 types of nuclei (>3500 species)

Subphylum: Postciliodesmataphora - share stacks of postciliary microtubular ribbons associated with somatic kinetosomes, and called postciliodesmata

Class: Heterotrichaea - adoral zone of membranelles macro nuclei divide via extra macronuclear microtubules. e.g. Stentor

Class: Karyorelictea - most are marine except Loxodes, alveoli absent in most

Subphylum: Intramacronucleata - dividing macronucleus that relies on intramacronuclear microtubules

Class: Armophorea - small, aneaerobic ciliates - e.g. see EOL website

Class: Listomatea - e.g. Lacrymaria olor and human parasite Balantidium coli

Class: Colpodea - e.g. Colpod sp. small bean shaped ciliate with uniform cilia

Class: Nassophorea - mouth leading to palisade of rods or nematodesmata

Class: Phyllopharyngea - in some only young have cilia e.g. chonotrics and suctoria

Class: Prostomatea - e.g. Coleps - charateristics see EOL website

Class: Plagiopylea - ciliates common in anaerobic habitats

Class: Olighymenophorea - ventral groove leads to cytosome e.g. Paramecium

Class: Protocurziea - see examples - ancestral form of ciliate?

Class: Spirotreachea - - prominent oral cilia e.g. Euplotes

Class: Cariotrichea - only one species Cariacothrix caudata from Venezuela

Subphylum: Mesodiniea - new group of cliates - more information (for Geeks only).

Spirostomum minus in a contracted state by Robert Berdan ©

Spirostomum minus in a contracted state. The contractile vacuole can be seen on the left in the posterior end. The zone of membranelles on the top right takes up about half the body length.

Photomicrography

For details on how I took these pictures please see my article - Tips on How to Take Better Pictures with a Microscope - Photomicrography. I used a Nikon D500 and Nikon D800 cameras, Zeiss Axioscope with DIC, Bright field, and Darkfield lighting, and controlled my cameras with free software Digicam control. Images were captured onto an Alienware laptop and processed in Adobe Photoshop. In many instances I needed to stack 2-12 images to increase the depth of field - for more information on this procedure see my article on focus stacking.

Summary

Ciliates are among the most complex and diverse unicellular organisms on the planet that form an important component of aquatic ecosystems acting as predators and providing nutrition for organisms at higher trophic levels. Ciliates are also important in the treatment of sewage water and water purification (Madoni 2011). My goal in this article was to share a small selection of photomicrographs and some interesting bits of information about these organisms and hope that it might inspire you to learn more about them.

Online References most or all the references can be found by a Google search

(2016) F. Gao et al. The All-Data-Based Evolutionary Hypothesis of ciliated Protists with a Revised Classification of the Phylum Ciliophora (Eukaryota, Alveolata). Nature scientific reports

(2016) First Record of Two Spirostomum Species of ciliates from Korea - download PDF.

(2016) T. Pattinson. The Freswater Microscopist - Part 2. Available on Blurb.com

(2015) T. Pattinson The Freshwater Microscopist. Available on Blurb.com

(2014) S. I. Fokin & V. Sera. The Hidden Biodiversity of ciliate-Endosymbionts Systems. Mini Review SciMedCentral - download PDF.

(2013) Morphology and 18S rDNA gene sequence of Spirostomum minus and Spirostomum terres from Rio de Janeiro, Brazil - Zoologia 30: 72-79 - download PDF.

(2012) C. Shao et. al. A redescription of the oxytrichid Tetmemena pustulata.... European J. Protistology. 49:272-282.

(2011) P. Madoni. Protozoa in wastewater treatment processess: A minireview. Italian. Journ. Zool. 78: 3-11.

(2007) D. H. Lynn The ciliated Protozoa. Springer Verlag.

(2007) W. Foissner, A. Chao, Laura A. Katz journal Biodiversity and Conservation, Volume 17, No 2, 345–363 - download PDF

(2004) N. G. Senler & I. Yildiz. Faunistic and Morphological Studies on ciliates from a Small Pond, with Responses of ciliate Populations to Changing Environmental Conditions - download PDF.

(2000) Illustrated guide to the Protozoa 2nd edition Society of Protozoologists. Allen Press, USA available on Amazon.com most recent Key to ciliates - check your library - excellent ref book.

(1999) W. Foissner, H. Berger and I. Schumberg. Identification and Ecology of Limnetic Plankton ciliates. Bavarian State Office for Water Management. 798 pages - download free ebook PDF

(1994) W. Foissner and S. Wölfl Revision of the genus Stentor Oken (Protozoa, Ciliophora) and description of S. araucanus from South American lakes. J. Plankton Res. 16: 225-289 - includes key to Stentors - PDF (see Dr. Foissner's other publications on his web site)

(1982) C. R. Curds British and Other Freshwater Ciliated Protozoa. Cambridge University Press.

(1972) H. Bick. Ciliated Protozoa World Health Organization, Geneva - free Ebook PDF

(1959) W.T. Edmondson Fresh Water Biology 2nd Ed. John Wiley, NY (Ward Whipple) - Keys to freshwater invertebrates (out of date but excellent illustrations). 1141 pages - Download PDF

(1953) W.J. Garnett Freshwater Microscopy. Constable & Co. Ltd London - Amazon.com $54.

Ciliates general reference - Wikipedia

Tear of a Swan - Lacrymaria olor - www.microscopy-uk.org

Paramecium (1985) ed H. D. Gortz Springer Verlag, NY

The Biology of Stentor (1961) Vance Tartar, Pergamon Press, NY

Freshwater Invertebrates - Ecology and General Biology (2010) eds J.H. Thorp & D.C.Rogers, Academic Press,NY - Excellent reference book - can purchase book from Elsevier

Pling Factory - In German use Google translation - Loxodes rostrum pictures and others

Microscopy from the very beginning - free book produced by Zeiss PDF

Boreal Science\Ward Science - can purchase some pond organisms

Quality Microscopes in Calgary - Zeiss dealer sells stereomicroscopes

Macrophotography.net - Forum on macro and photomicrography

Photographing Ciliates

by Dr. Robert Berdan

July 17, 2018

Spirostomum minus (top) and Urocentrum turbo by Robert Berdan ©

Spirostomum minus (top) and Urocentrum turbo (bottom) - both are common ciliates in fresh water. DIC (differential interference microscopy) A micron = 1\1000 of a millimetre.

Introduction to the ciliates