Branchiopods (Water Fleas, Fairy Shrimp)

This group gathers Crustaceans subcategory members belonging to the class Branchiopoda, a largely freshwater crustacean class named for leaf-like limbs that combine swimming, feeding and breathing functions in one structure. It spans the water fleas, tiny, jerkily swimming crustaceans of the genus Daphnia and its relatives, a favored laboratory organism for genetics and toxicology research thanks to a short life cycle and near-transparent body that makes internal organs easy to observe, and the fairy shrimp and tadpole shrimp, delicate, often brightly colored crustaceans specialized for life in temporary pools, puddles and vernal ponds that dry up completely for part of the year, surviving the dry season as tough, drought-resistant eggs that can remain dormant in dried mud for years before hatching when the pool refills. Nearly every member here plays an outsized ecological role in the small, often overlooked freshwater habitats it occupies, despite a body size measured in millimeters.