Mysidacea

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Mysidacea

The ventral side of Mysis

Scientific classification

Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Crustacea
Class:	Malacostraca
(unranked)	Mysidacea

Orders & Families

Lophogastrida G. O. Sars, 1870
- Eucopiidae
- Lophogastridae
Mysida A. H. Haworth, 1825
- Mysidae
- Lepidomysidae
- Petalophthalmidae
- Gnathophausiidae

The Mysidacea is a group of small, shrimp-like creatures including the species Neomysis americana, comprising the two related orders Mysida and Lophogastrida. They are sometimes referred to as opossum shrimps, though that name is also used for individual species.

Note that despite their name, and their superficial resemblance to shrimp, they are only quite distantly related to the true shrimps, which are classified in the order Decapoda. The characteristics of the Mysidacea include the following:

They have a well developed carapace that covers most of the thorax, but it is never fused with more than four of the thoracic segments
Their pereiopods are biramous (i.e. separated into two branches), except sometimes the last pair, which may be reduced
Their pleopods are reduced. In males they may be modified
They usually have a statocyst in the endopods of their uropods
Their eyes are on stalks