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Mysids: Mysida

No Common Name (stygiomysis Cokei): Species Accounts

Physical characteristics: Adults measure 0.35 to 0.86 inches (9.0 to 22.0 millimeters). The carapace is about one-fifth of the entire length of the body. The first pair of antennae (antennules) are about one-half the body length. The marsupium is made up of four plates. The telson has fifteen spines arranged in five groups of three and is about one-sixth the length of the body.

Geographic range: Stygiomysis cokei is found in coastal inland caves near Quintana Roo, Yucatan Peninsula, Mexico; in Mayan Blue Cave; Carwash Cave; and Naharon Cave.

Habitat: These cave dwellers live in the freshwater layer at depths of 32.8 to 65.6 feet (10 to 20 meters). They are also found in the upper layers with slightly brackish waters. They prefer habitats with These cave dwellers live in the freshwater layer at depths of 32.8 to 65.6 feet (10 to 20 meters). (Photograph by Jerry Carpenter. Reproduced by permission.) relatively constant temperatures ranging between 76.1° to 77.9°F (24.5° to 25.5°C).

Diet: Stygiomysis cokei is primarily a filter feeder.

Behavior and reproduction: Little is known about how this species behaves under natural conditions. When disturbed, they will swim with awkward movements. Nothing is known about their reproductive behavior.

Stygiomysis cokei and people: This species is not known to impact humans or their activities directly.

Conservation status: This species is not considered endangered or threatened. ∎



Brusca, Richard C., and Gary J. Brusca. Invertebrates. Sunderland, MA: Sinauer Associates, 2003.

Mauchline, J. The Biology of Mysids and Euphausiids. Part I. The Biology of Mysids. London: Academic Press, 1980.


Grossnickle, N. E. "Feeding Habits of Mysis relicta—An Overview." Hydrobiology 93 (1982): 101-107.

Web sites:

"Biology of Opposum [sic] Shrimps." Mysidacea Gallery. http://www.museum.vic.gov.au/crust/mysibiol.html (accessed on February 21, 2005).

Mysis relicta. http://nas.er.usgs.gov/queries/FactSheet.asp?SpeciesID=1142 (accessed on February 22, 2005).

Additional topics

Animal Life ResourceMollusks, Crustaceans, and Related SpeciesMysids: Mysida - Physical Characteristics, Habitat, Behavior And Reproduction, Mysids And People, Conservation Status, No Common Name (mysis Relicta): Species Accounts - GEOGRAPHIC RANGE, DIET