Idiosepiidae, also known as the pygmy squids, is a family of squids in the superorder Decapodiformes.[2][3] They are the smallest known squids.[3]
It is the only family in the monotypic order Idiosepida[4] and the monotypic superfamily Idiosepioidea.[5] Phylogenomic analyses have shown that species in the family Idiosepiidae are sister to all other Decapodiformes.[6]
Idiosepiidae are the smallest known squids: males can grow to about 15 mm (0.6 in) and females to about 21 mm (0.8 in) in mantle length. The mantle is elongate, obovate to cigar-shaped, with its posterior margin bluntly pointed at the distal tip. The head is prominent while the arms are short. In males, both ventral arms are differentiated, but they are also different from each other.[3]
Idiosepiidae have an Indo-west Pacific distribution, from South Africa in the west to Japan and Russia in the east. They appear to be short-lived. They generally live in shallow water among seagrass and mangroves. They often adhere themselves to substrate, enabling camouflage and concealment during the day. They appear to be sit-and-wait predators. They are solitary. Mating is promiscuous with multiple matings. Young individuals are planktonic.[3]