Malacostracan Crustaceans Terminology

(Definitions after Jones and Morgan, 1994)

abdomen - the terminal zone of the body, lying posterior to the thorax.

ambulatory - modified for walking, as in pereopods of malacostraca or phreatocoid uropods.

antenna (pl. antennae ) - usually elongate sensory appendages on the head.

antennules - the first, small pair of antennae on the head of crustaceans.

basis - the distal (furthest from body) section of the protopod (crustacean appendage).

bi-articulate - double-jointed.

biramous - having two branches (endopod and exopod), typically arising from a basal portion (protopod).

bivalve - the carapace consists of two hinged valves.

calcareous - rich in calcium e.g. the exoskeleton of crustaceans.

carapace - the protective exoskeletal shield covering part or all of the dorsal and lateral thorax.

caudal rami - paired long tail-like structures on the last abdominal segment of some crustaceans.

chela (pl. chelae ) - prehensile claw(s).

chelate - pincer-like.

coxa - the proximal (nearer to body) section of the protopod (crustacean appendage).

endite - a mesal branch of a protopod (crustacean appendage).

endopod (ite) - the inner branch of a protopod (crustacean appendage).

epipodite - a lateral branch of a protopod (crustacean appendage).

exopod (ite) - the outer branch of a protopod (crustacean appendage).

flagellum - a whip-like extension, as of accessory flagellum on antenna.

gills - membraneous extensions of the body that permit oxygen exchange.

gnathopod - a pereopod modified for grasping, ie with some kind of claw.

lacinia mobilis - a mobile tooth-like appendage of the mandibule.

mandible - one of a pair of jaws - the most anterior mouthparts.

mesal - nearer to the midline of the body, also medial.

orbit - the eye socket.

palp - a jointed sensory appendage of the maxilla or labium.

pereon - a group of free thoracic segments.

pereonite - one segment of the thorax bearing locomotory appendages.

pleon - a group of abdominal segments bearing the pleopods.

pleonite - one segment of the abdomen bearing locomotory appendages.

pleopods - the paired appendages found on any of the first five abdominal segments of crustaceans, typically used for swimming.

pleotelson - the body segment formed by the fusion of terminal abdominal segments to the telson.

protopod ( -podite ) - the base of a crustacean appendage to which the two-part (biramous) appendage is attached.

protopod (ite) - a crustacean appendage, comprising a proximal coxa and distal basis.

ramus (pl. rami ) - a branch (as of a limb).

rostrum - a median extension to the body, notably between the eyes.

rugosity (adj. rugose ) - granular or tubercular projections on the surface.

somite - a segment (thorax or abdomen).

tail fan - the tripartite tail comprising two uropods and median telson.

telson - the terminal part of the body joined to the last (sixth) abdominal segment (often a sharp triangular spike). Together with the adjacent uropods it forms the tail fan of many decapods.

thorax - the zone of the body lying behind the head, anterior to the abdomen.

triturating - grinding, as of mandible.

uni-articulate - single-jointed.

uniramous - not branched (crustacean appendage).

urosome - a group of abdominal segments bearing uropods. In amphipods, the two terminal segments have their pleopods modified into uropods, so the urosome comprises the last three segments - the most terminal of which bears the telson and third ('true') uropods.

vermiform - worm-like.