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If I'm correct the two ostracods in the photo are both Bradleystrandesia tincta . If both animals come from the same pool at the same time would that indicate the color differences are genetic rather than environmental? If genetic is the difference indication of different "breeds" of the same species and how is it the one color pattern (if one is a dominant gene and the two types cross mate) does not disappear over time in the the same pool. In the pool looked at the two color patterns were found in about equal numbers. If they are not the same species than the question is mute.
Below is the pool where found.
B. tincta with Candona decora.
Dr. Alison J. Smith, Professor
Department of Geology Kent State University
Hi John, I think what they eat is important. Pigments released from the algae and especially diatoms they consume play a role. On the other hand, some species have distinct banding, as in Cypridopsis vidua, but the bands have variation from individual to individual, being anything from light green through dark brown. I will be interested to see from Contributors to this discussion what other factors are in play when it comes to color.
Best regards, Alison
Emi ito, Professor,
CSENG Earth Sciences, Dept of (office: Geology and Geophysics) UMN Twin Cities
Nori Ikeya did an experiment years ago where he and his students fed goldfish flakes to ostracodes. They fed red flakes to some, green flakes
to others, etc., and showed that their colors reflected what they ate. I don't know much more (he told me this during a tea break when I was in his
lab) but I think these were marine or estuarine ostracodes without any spots or stripes on carapaces. Tsukagoshi may know more.
Dave Horne
Professor of MicropalaeontologySchool of Geography Queen Mary, University of London
John, I don't know the species but both illustrated specimens look like juveniles to me. On the question of colour, is it possible that the differences are related to the length of time since the animal last moulted?
Me
I'm 95% sure these are not juveniles, I've looked at over 100 pools and this is as big as they get in Northern Ohio and the same difference in color can be found in many pools. I've added a photo of B. tincta with an female adult C. decora found in the same pool for size comparison.
Karl-Franzens-Universität Graz , Graz Systematics (Taxonomy), Zoology, Limnology
Dear Colleagues, the color of ostracods is a complex problem. Already G.W. Mueller in his famous Monograph of the Naples bay ostracods has wonderful representation. Now John Lavelle is confronted with apparently same ostracods 2 color morphae. Can be due to different food items ingested and it is clear that food can produce a color which mimics a genetical cued fixed color. There are ostracods like Cypria ophthalmica which display a brouwn color. Candona inaequivalvis baikalensis in a sample I investigated had a completely brown color however Candoninae do not display a pigmented epithelial valve and as also the limbs were colored in brown I assume that here the ingested algal food play the major role for our Baikalian species. There are other species like Cypridopsis vidua which one finds in the same place (for instance in the littoral of lake Mondsse where the color pattern is either black or brown. Here the Okam's razor rule I would adopt is a genetic cued process which exist in different clones. There is also a typical phenotypic adaptation where color differs because of the selective pressure of different actors playing in the environment where an ostracod species is active. for this last aspect one could maybe have a look to the publication of Livia Casale & myself, 1990, To see and not to be seen, the evolutionary problems of ostracods, we published in the monograph Cytherissa (Bulletin Inst. Geol. Bas. d'Aquitaine, vol 47, 227-238.
Maybe one should add that ocular pigment of Potamocypris species vary also from red to black depending on the environment. There is not a problem of food but of light intensity, those animals leaving into the deeper sediment layer tend to be have a low pigmented body and the the eye pigment is red. In Cypria a cavernicolous species looses completely of both valves and eyes....So best wishes to all of you!
Dr. Alison J. Smith, Professor
Department of Geology Kent State University
Regarding the color discussion, you are right, there is alot of "anecdotal" information, but that is about it. There is a story in there, because if you were to be collecting the California vernals, you would find the ostracodes in there to be BLUE. Really. A lovely robin's egg blue. I tried some years ago to capture the color variation in a photo I called the bowl of jellybeans photo, which is in the Thorp & Covich 3rd edition. There is some complex story of genetics, defense coloration and food that is driving the colors we see. But no one as far as I know has worked it out. (My emphasis)
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BIG NUMBERS
(Or why these little critters matter)
As anyone following this small project must have realized by now there is a major focus on the crustaceans of all the bodies of water sampled. These animals, the ostracods, copepods, cladocerans are not some strange little unimportant creatures of wetlands and vernal pools they are the major animal biomass of almost all these areas sampled. Crustaceans are indeed the greatest living biomass of animal life on the planet. One of the strangest things to witness is how much they are ignored. At Old Woman's Creek there is a interpretative center with display after display of life in the waters of the national estuary there. Yet when I visited not a single mention of these animals that dominate the waters of the estuary was seen. If not found here than where does one look. When vernal pool and wetland workshops are held crustaceans are lumped into the catchall category of macro-invertebrates and given short shrift if mentioned at all. The view of life in these waters is totally skewed. Salamanders and frogs are delightful and special creatures, they are also cute but to focus so much on them is like looking at elephants and giraffes and ignoring all the other mammals that make up the African ecosystem. And let us not forget the rotifers even more ignored; this is the phylum that may have evolved in freshwater thus holding a special place yet how many poolers and wetlanders have ever actual seen one or can name those common to the pools around them.
Below is a very rough estimate of the numbers that can be found in a typical small wetland which I hope forcefully makes apparent the enormous role the crustaceans play in these waters and in the entire forest.
The area can be better considered a temporary wetland than a vernal pool because of its size. By late June last year the pool was gone.
Cyclopoid copepod 111
Harpacticoids 25
Ostracods 68
Calanoids 1
Amphipods 3
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208 total crustaceans
If a ballpark conversion is used (see numbers below) the pool being very roughly 50 meters length X 20 meters width and while the pool is 10 to 20 cm. deep only the bottom three cm. are used. This is because most of the crustaceans live at the interface of the bottom and water. But the bottom is covered with leaf litter that semi-floats above the hard bottom providing for a many layered substrate. The sample taken does not cover anywhere near a square meter it is probably closer to 0.25 square meter in area so it would't be unreasonable to multiply the total number by 4 but for simplicity sake will say 1/2 sq meter is the sample area. The sample is taken from 4 or 5 different location to hopefully eliminate the possibility of swarming in one total.
Put all the numbers together and astounding 1,548,000 are possibly living in this one pool.
This number can easily be multiplied from between 2 to 4 since far less than a square meter of bentos is actually sampled and the entire upper waters of the pool is not counted those these waters are home to a great number of copepods and later in the year cladocerans.
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Pool size - approximate 50 meters X 20 meters
5000 cm. X 2000 cm. = 10,000,000
Depth 3 cm. 3 X 10,000,000 = 30,000,000 cm2 = 3000 m³
208 crustaceans in 0.5m so 516 per m² 516 X 3000 = 1,548,000
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Below photos from different pools
Ostracods
Calanoid Copepod Harpacticoid copepod
Three cyclopoid copepods
Three cladocerans
Three rotifers
Two photos of a colonial rotifer
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