Nannastacidae is a family of crustacean

Crustacean

Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s belonging to the order Cumacea

Cumacea

Cumacea is an order of small marine crustaceans, occasionally called hooded shrimp. Their unique appearance and uniform body plan makes them easy to distinguish from other crustaceans.-Anatomy:...

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Anatomy

Nannastacidae have no free telson

Telson

The telson is the last division of the body of a crustacean. It is not considered a true segment because it does not arise in the embryo from teloblast areas as do real segments. It never carries any appendages, but a forked "tail" called the caudal furca is often present. Together with the...

. The endopods (interior branches) of the uropods are present on one segment. There are exopods (outer branches) on the maxillipeds and generally one on pereopods 1–4 in males and 1–2 in females. Males possess five pairs of pleopods. In the females the second antenna is much shorter than the first.