''Clausidium vancouverense'', the red copepod, is a symbiont of the ghost shrimp ''

Neotrypaea californiensis ''Neotrypaea californiensis'' (formerly ''Callianassa californiensis''), the Bay ghost shrimp, is a species of ghost shrimp that lives on the Pacific coast of North America. It is a pale animal which grows to a length of . One claw is bigger ...

''. It is one of six species in the genus '' Clausidium'' and is found with its host in the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

from

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

Description

Females range in length from . The female is larger than the male, and a female sometimes carries a male attached to her dorsal thorax. Several features separate this copepod from other species in its genus. These include the blade-like

seta In biology, setae (singular seta ; from the Latin word for "bristle") are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Annelid setae are stiff bristles present on the body. Th ...

on the first leg and the small lateral hairs on the setae of the fifth leg on females. In males, the structure of the

maxilliped An appendage (or outgrowth) is an external body part, or natural prolongation, that protrudes from an organism's body. In arthropods, an appendage refers to any of the homologous body parts that may extend from a body segment, including anten ...

is unique.

Ecology

Copepod distribution of a similar species '' Clausidium dissimile'' on ghost shrimp were positively correlated to the host's body size, but host sex did not affect distribution. ''C. vancouverense'' sticks to the branchial cavity of its host via suckers.

References

{{Taxonbar, from=Q3809074 Poecilostomatoida Crustaceans of the eastern Pacific Ocean Crustaceans described in 1912