Tags: Crustacean.
Cladocera is an order of small crustaceans commonly called water fleas. Around 620 species have been recognised so far with many more undescribed. They are ubiquitous in inland aquatic habitats but rare in the oceans. Most are 0.2–6.0 mm (0.0079–0.2362 in) long with a down-turned head and a carapace covering the apparently unsegmented thorax and abdomen. There is a single median compound eye.
