The Mysidacea is an order of small, shrimp-like creatures including the species Neomysis americana (opossum shrimp). They are sometimes referred to as Mysida (as a common name, not a systematic name) or collectively as opossum shrimps, though that name is also used for individual species.

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

External links

• Gary Anderson, Wayne Price and Richard Heard's Mysida website (http://tidepool.st.usm.edu/mysids/index.html)
• Tim Deprez's website on Mysida (http://allserv.rug.ac.be/~tdeprez/Mysidacea/)