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.