The marsupium or brood pouch, is a characteristic feature of

Peracarida The superorder Peracarida is a large group of malacostracan crustaceans, having members in marine, freshwater, and terrestrial habitats. They are chiefly defined by the presence of a brood pouch, or ''marsupium'', formed from thin flattened plat ...

, including the orders

Amphipoda Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far descri ...

Isopoda Isopoda is an order of crustaceans that includes woodlice and their relatives. Isopods live in the sea, in fresh water, or on land. All have rigid, segmented exoskeletons, two pairs of antennae, seven pairs of jointed limbs on the thorax, and ...

Cladocera The Diplostraca or Cladocera, commonly known as water fleas, are a superorder of small crustaceans that feed on microscopic chunks of organic matter (excluding some predatory forms). Over 1000 species have been recognised so far, with many more ...

, and

Cumacea Cumacea is an order of small marine crustaceans of the superorder Peracarida, occasionally called hooded shrimp or comma shrimp. Their unique appearance and uniform body plan makes them easy to distinguish from other crustaceans. They live in so ...

. It is an egg chamber formed by

oostegite An oostegite is a large, flexible plate-like flap extending medially from the coxae (first segments) of the pereiopods (thoracic appendages) in some female Female (symbol: ♀) is the sex of an organism that produces the large non-motile ...

s, which are appendages that are attached to the coxae (first segment) of the first

pereiopod 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 variou ...

s. Females lay their eggs directly into the brood chamber, and the young will develop there, undergoing several

moult In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...

s before emerging as miniature adults referred to as

manca The manca (plural: ''mancae'') is the post-larval juvenile in some crustaceans. The manca stage is the defining characteristic of a clade called Mancoida which comprises all the member of the Peracarida except the Amphipoda. Mancae closely resembl ...

e. Males have no marsupium.

References

{{malacostraca-stub Crustacean anatomy