Daphnia Daphnia are very useful for testing pollution amounts in water. They are used as markers. Daphnia are small fresh water crustacean. They are of the Chydoridae family. Daphnia are related to lobster, crab, shrimp, and crayfish.
Daphnia are very advanced microscopic creatures.
Like most crustaceans, they have a hard shell made of a chemical called chitin. Its shell is really made up of two pieces. They separate in the middle of the body. Daphnia have branched legs like structures that act as feet. They are actually antennae that come out of the top of the head.