Mysidacea
Gnathophausia zoea
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 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 (e.g. Neomysis americana).

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

The name "opossum shrimp" is derived from the females' brood pouch, formed by plates attached to the front legs. The larvae are carried in the pouch until they are able to move by themselves. Although they most commonly occur at sea, they are abundant in certain bodies of fresh water, such as the Great Lakes; some are occasionally found in caves. Wherever mysids occur, whether in salt or fresh water, they are often very abundant and form an important part of the normal diet of many fishes. In many Asian countries, mysids are a common part of local cuisine, and in certain regions, such as the Gulf of Thailand, they support extensive fisheries. Mysids are also used as a bioassay for toxins in seawater. ^[1]

[edit] Systematics

Although the traditional grouping of Mysida and Lophogastrida into Mysidacea has had strong morphological support, recent molecular studies question the monophyly of this group.^[2][3]

[edit] References

[edit] External links

Wikispecies has information related to: Lophogastrida

Wikispecies has information related to: Mysida

• Mysidacea fact sheet - Guide to the marine zooplankton of south eastern Australia
• Gary Anderson: Peracarida Taxa and Literature
• Tim Deprez's website on Mysida
• Mysid, Americamysis bahia, Photo and Information at MBL Aquaculture
• Kenneth Meland's Mysidacea page (crustacea.net)