Daphnia Magna, L0281 (jar)

Daphnia are tiny crustaceans, never growing larger than a couple of millimeters no matter how well they eat. They are sometimes called water fleas because they are about that size and superficially look like fleas. But unlike fleas they are nearly transparent, live in water, have a shell, and are graced with an interesting array of modified appendages for sensing, feeding, and swimming. As they travel they filter even tinier organisms from the water. They feed on single-celled algae, yeast, and bacteria. Daphnia in turn are eaten by fish and aquatic insects.