Eurycercus lamellatus

AN REAL ELEPHANT AMONG THE WATER FLEAS, up to 4 mm ! But a very light footed elephant: most of the time this water fleas hangs on filament algae and water plants with its little legs. This very common water flea is a fast swimmer and has not the hopping movements of other water flea. Eurycercus also crawls in the detritus(waste) layer on the water bottom. Bacteria and freshly died material in the detritus layer are probably the main nutrient. Research has shown that Eurycercus chooses the bottom especially when there are predators present in the water that eat Eurycercus. And they do seem an easy an easy prey when stationary on the water plants, like "sitting ducks". Ironically for ducks like the Tufted Duck and the Scaup they are an important meal. Many fish eat Eurycercus and the water measurer can catch them as this photo shows. Eurycercus is a genus in the Chydoridae family, named after the also common Chydoris sphaericus, all species which sit most of thee time on water plants or crawl on the water bottom. Even on a water spiders thread the walk with ease as you see on the picture at the right. All the the pictures show that the lower forward corners of the shell halves hang over the thread (algae) from which Eurycercus hangs, a bit like a monorail train.
The female specimen on the left shows clearly the (normal) eggs in the breeding pouch. This pouch is large, the water flea itself isn't really that big! The twisted intestine is remarkable, also on the picture on the right.

Like all Chydorides, Eurycercus is able to sit in any position on the water plants. On the pictures on the left a specimen is hanging upside down on a leaf, and so the legs the opening of the shell are visible. The picture on the right shows a specimen sitting straight up on a water plant, and links to more photo's

Finally a picture of a smaller specimen (0.8 mm). This could be a male, they grow no bigger than 1.5 mm.


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