Colpoda is a genus of in the class Colpodea, order Tetrahymenida, and family Colpodidae.
Description
Colpoda are distinctly reniform (kidney-shaped) and are strongly convex on one side, and concave on the other. The concave side often looks like a bite was taken out of it. Although they are not as well known as the
paramecium, they are often the first
protozoa to appear in
, especially when the sample does not come from an existing mature source of
Water stagnation.
Habitat
Colpoda are often found in moist
soil and because of their ability to readily enter protective
Microbial cyst will quite frequently be found in desiccated samples of soil and vegetation
as well as in temporary
such as
tree throw.
They have also been found in the
of various animals, and can be cultured from their droppings.
Colpoda cucullus has been found inhabiting the surface of plants and seems to dominate the microfauna there. Several species of Colpoda have been found in the pitcher plant Sarracenia purpurea, despite the presence of protease digestive enzymes in the liquid.[ biolbull.org
THE PROTOZOA OF THE PITCHER PLANT, SARRACENIA PURPUREA R W Hegner]
Colpoda also tends to be found in abundance where increased levels of bacteria offer an enriched food source. In commercial , for example, they seemed to be ubiquitous but the species found vary widely from one location to the next, suggesting that these populations represent local soil and aquatic populations which migrated into the new habitat.
In addition to inhabiting a wide variety of , Colpoda can be found almost everywhere around the world where there is standing water or moist soil, even where these conditions are only ephemeral. Colpoda brasiliensis for example was discovered in in 2003.
Not only is the genus widespread, but there are also several species that have nearly global distribution, and, indeed, it has been suggested this may be true of all species, a fact that could be borne out by better investigation.
Reproduction and conjugation
Colpoda normally divides into cysts, from which two to eight individuals emerge, four being the most common number. This produces genetically identical individuals. The rate at which such reproduction occurs and how it is affected by various environmental conditions has been the subject of a great deal of scientific research.
On rare occasions, Colpoda have been observed to divide into 4 individuals without producing a cyst wall. It has been suggested that cyst less reproduction was the normal mode of reproduction for Colpoda under optimum conditions and that the formation of cysts was a reaction to adverse environmental conditions. However, the knowledge gained by many years of culturing Colpoda in hay infusions has shown that this mode of reproduction remains rare despite what would seem to be ideal environmental conditions.
As in other ciliates, division in Colpoda may be preceded by a sexual phenomenon known as conjugation. This involves two Colpoda joining at the oral groove and exchanging DNA. Following conjugation, the Colpoda divides, redistributing the DNA of the two original cells to produce numerous genetically distinct offspring.
Ecological role
Most
Colpoda species are either primarily or exclusively
feeding on a wide variety of bacteria, which include
Moraxella. Several scientific studies have been made on the effect of different bacterial diets on the rate of
Colpoda reproduction. Much has been written on the ecological role that
Colpoda fulfill in the soil.
In addition to their role as predators of bacteria, Colpoda are themselves prey to a large variety of species. This includes other as well as small animals such as mosquito larva,
Uses by humans
In addition to their use in education and in a wide variety of scientific studies,
Colpoda have at times been suggested for more practical uses.
Colpoda steinii has been suggested as a means to assess the toxicity of soil treated with
sewage sludge[Use of Colpoda steinii to bioassay the toxicity and bioavailability of heavy metals in a long term sewage sludge-treated soil., Campbell, C.D., Warren, A., Cameron, C.M. and Hope, S.J., (1995) British Section of the Society of Protistologists, Annual Meeting, Liverpool, 27–29 March 1995.] and as a means to detect chemical contamination in general, possibly in the wake of a
terrorist attack.
Species
-
Colpoda acuta - Found in central Europe, it was first described in a paper published in 1977.
-
Colpoda aspera - A fairly small species, 12-42 micrometres, noted for being less reniform than other species. Found in Antarctic, Subantarctic
[http://data.aad.gov.au/aadc/biodiversity/taxon_profile.cfm?taxon_id=113907 Biodiversity - SCAR EBA program Taxon Profile][Petz, W.; Foissner, W. (1997) Morphology and infraciliature of some soil ciliates (Protozoa, Ciliophora) from continental Antarctica, with notes on the morphogenesis of Sterkiella histriomuscorum Polar Record 33, Issue 187 307-326pp.][http://www.eol.org/pages/2915349?category_id=290 Encyclopedia of Life]
-
Colpoda brasiliensis - A small species, 18-33 micrometres, noted for its mineral envelope which acts as a passive defense against predators. Named for the country in which it was discovered.
-
Colpoda californica
-
Colpoda cavicola
-
Colpoda cucullus - A fairly widespread species noted for being the dominant protozoan on the surface of plants.
-
Colpoda discoidea
-
Colpoda duodenaria - A small to medium-sized species, first described by Charles Vincent Taylor and Waldo Furgason
[http://books.nap.edu/html/biomems/ctaylor.pdf Biography of Charles Taylor] and widely studied for the effects of various chemicals on its excystment process.[http://www.soc.nii.ac.jp/jsproto/journal/jjp37/119-126.pdf Effects of porphyrins on encystment and excystment in ciliated protozoan ]
-
Colpoda ecaudata
-
Colpoda elliotti - A small species, 15-28 micrometres, noted as having been cultured from deer droppings.
-
Colpoda eurystoma
-
Colpoda fastigata
-
Colpoda formisanoi
-
Colpoda fragilis
-
Colpoda henneguyi - Widespread medium to large species, 30-80 micrometres, noted for its habit of staying perfectly still for long periods of time, making it easy to photograph live.
[http://www.eol.org/pages/486915 Encyclopedia of Life]
-
Colpoda inflata - Possibly one of the best known and most common species, noted for its fitful resting stage in which it jerks around in a tight circle, frustrating microscopists trying to photograph it live.
[http://www.eol.org/pages/486913 Colpoda inflata Stokes, 1885]
-
Colpoda irregularis - This species is noted for a prominent post oral sac and was cultured from moss and soil crust from rocks near desert sagebrush of southwest Idaho.
-
Colpoda lucida
-
Colpoda magna - A large species, 120-400 micrometres long. Appears dark at lower powers because of dark structures near the contractile vacuole. Often completely packed with food .
[http://www.eol.org/pages/2909580 Encyclopedia of Life]
-
Colpoda maupasi - Once thought to be a variety of Colpoda steinii, later recognized as a separate species. Classically it was believed to produce only reproductive cysts containing 8 offspring. One strain, however, the Bensonhurst strain, was found to also produce reproductive cysts containing 4 offspring.
-
Colpoda ovinucleata
-
Colpoda patella
-
Colpoda penardi
-
Colpoda praestans
-
Colpoda quinquecirrata
-
Colpoda reniformis
-
Colpoda rotunda
-
Colpoda simulans - A medium-sized Colpoda with the classic "bite taken out of it" Colpoda shape.
[http://protist.i.hosei.ac.jp/pdb/images/Ciliophora/Colpoda/simulans.html Protist images]
-
Colpoda spiralis - A very unusual species with a large overhang that gives it an almost snail-like appearance. It was first found in Arizona
[http://www.3dham.com/colpoda_spiralis/ Colpoda spiralis ? found in Northern California]
-
Colpoda steinii - A widely distributed small to mid-sized species, 14-60 micrometres, usually free living but capable of being parasitic to .
-
Colpoda tripartita
-
Colpoda variabili
Videos
Click on images before playing them to see full size (reload (F5) if you already hit play)
Image:Colpodacircus100x1.ogg|several dozen various sized Colpoda representing at least 3 species with other ciliates 100X
Image:Bigcolpoda100x1.ogv|Large Colpoda amongst many smaller ones with other ciliates 100X
Image:Detailedcolpoda400x1.ogg|Detailed video of Colpoda in resting stage 400X
Image:Detailedcolpoda400x2.ogg|Another view of Colpoda in resting stage, showing relative sizes 400X
Image:Colpodaspiralis400x1.ogg|Unusual Colpoda, possibly Colpoda spiralis 400X
Image:Colpodaspiralis1st.ogg|Unusual Colpoda, possibly Colpoda spiralis From when it was first spotted.
Image:Colpodastuck.ogg|Several colpoda, seemingly stuck to debris 100X
Image:Colpodaharrass400x1.ogg|Active Colpoda seems to harass a resting Colpoda Magnified 400 times
