Apus: Morphology, Classification, Habitat, and Life History of the Tadpole Shrimp Apus is a genus of freshwater crustaceans commonly known as tadpole shrimps, belonging to the order Notostraca within the class Branchiopoda. Distinguished by their shield-like carapace and elongated bodies, tadpole shrimps are ancient crustaceans often considered living fossils, showing little change since the Triassic period. Apus species inhabit temporary ponds, marshes, and ditches, exhibiting remarkable adaptations for surviving in unpredictable and ephemeral aquatic environments.