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Peracantha truncata
Peracantha truncata
The scale has ribs...
Peracantha truncata
...and spined borders.
Peracantha truncata
Two eyes: complex- and nauplius.
Peracantha truncata
The body is white.
Peracantha truncata
The large dot is the complex eye.
Peracantha truncata
The Water flea is...
Peracantha truncata
...scratching on Waterplants...
Peracantha truncata
...and takes all kinds...
Peracantha truncata
... of postures.
Peracantha truncata
Rear view.
Peracantha truncata
One antenna extended.
Peracantha truncata
Bottom view.
Peracantha truncata
The scale opening is wide.
Peracantha truncata
Bottom view.
Peracantha truncata
With Cyclops (unsharp)
Peracantha truncata
With Cyclos Nauplius larva

Peracantha truncata

The name of this common waterflea, Peracantha means "with spines on" (cantha - thorn,spine, acantha - spined) and truncata is, of course, "truncated". The little crustacean indeed seems a bit truncated when compared to the most, round shaped species of water fleas, and there is a row of spines on each "truncated" end of the scale halves. The scale also has a nice ribbed surface. What the purpose of these facts is, I don't know. The frontal margins of the scale has spines which are curved outwards. Maybe they lend better support when the waterflea is clamping on to the stems of waterplants. According to some investigations it is in any case a adaption to their way of life¹). The slit of the scale is wide, so the waterflea may sit firm on the waterplants and providing a large "scraping surface".

peracantha, scale front margin and claws on feet 29-07-2007
Scale front margin and claws on feet
(Click for a overall view)
peracantha

Peracantha is a genus within the Chydoridae family, a group of waterfleas living on waterplants and on the bottom. The family is named after the roundly shaped Chydorus species. The large and very common Eurycercus lamellatus is also a member of this family. Peracantha scratches on waterplants to scrape of algae and other small food particles, for that purpose the legs are provided with claws and bristles. This waterflea is also able to swim with its second pair of antennae, but when crawling they are not useful and folded away under the scale, making the waterflea less conspicuous to its predators. The head has two eyes above each other: a large compound eye and a smaller, single eye, called a nauplius eye. (A Nauplius is a larval stage of crustaceans having such an eye).


1) Fryer, G. : Evolution and Adaptive Radiation in the Chydoridae (Crustacea: Cladocera): A Study in Comparative Functional Morphology and Ecology


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All pictures on this site were made by Gerard Visser (Almelo, Netherlands), unless stated otherwise. All rights remain with him. These pictures may not be used for purposes any other than private viewing or printing. Do NOT hardlink to these pictures or place them on other websites without the author's approval. Should you need them for purposes which include third parties, you must ask the author permission by e-mail. People, who want to use this pictures for exhibitions or publications or educative material are much encouraged to do so, after approval as mentioned and giving the normal credits.
© G.H. Visser 21-10-2007
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