Petalophthalmidae is a

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

of marine

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

s in the

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

Mysida Mysida is an order (biology), order of small, shrimp-like crustaceans in the malacostracan superorder Peracarida. Their common name opossum shrimps stems from the presence of a Brood pouch (Peracarida), brood pouch or "marsupium" in females. The ...

, the opossum shrimps.

Characteristics

Petalophthalmidans are distinguished from other mysids by the fact that the first

pereopod The decapod (crustaceans such as a crab, lobster, shrimp or prawn) is made up of 20 body segments grouped into two main body parts: the cephalothorax and the pleon (abdomen). Each segment may possess one pair of appendages, although in various g ...

(walking leg) does not have an exopod (outer branch), the carpopropodus of the endopod (inner branch) of the 3rd to 8th pereopods are not fused and there is no

statocyst The statocyst is a balance sensory receptor present in some aquatic invertebrates, including bivalves, cnidarians, ctenophorans, echinoderms, cephalopods, and crustaceans. A similar structure is also found in ''Xenoturbella''. The statocyst cons ...

on the endopod of the

uropod Uropods are posterior appendages found on a wide variety of crustaceans. They typically have functions in locomotion. Definition Uropods are often defined as the appendages of the last body segment of a crustacean. An alternative definition sugge ...

s (posterior appendage). Female petalophthalmidans have seven oostegites (flexible bristly flaps) forming the base of the marsupium or brood pouch under the thorax. Most species in this genus are

bathypelagic The bathypelagic zone or bathyal zone (from Greek βαθύς (bathýs), deep) is the part of the open ocean that extends from a depth of below the ocean surface. It lies between the mesopelagic above, and the abyssopelagic below. The bathypelagic ...

and live on or near the seabed in the deep ocean.

Genera

The following genera are recognised in the World Register of Marine Species: **Genus '' Bacescomysis'' Murano & Krygier, 1985 **Genus '' Ceratomysis'' Faxon, 1893 **Genus '' Hansenomysis'' Stebbing, 1893 **Genus '' Parapetalophthalmus'' Murano & Bravo, 1998 **Genus '' Petalophthalmus'' Willemoes-Suhm, 1875 **Genus '' Pseudopetalophthalmus'' Bravo & Murano, 1997

References

{{Taxonbar, from=Q4517366 Mysida Crustacean families