Terminology Description
Terminology Description
Basal margin The lower margin of a plate in barnacles.
Basal plate The bottom plate and place of attachment for barnacles. May be calcareous or membranous.
Beak The lower curved angle of the scutum in goose barnacles or the apex of the tergum with a curved beak-like point in other barnacles.
Bicuspid Having two points.
Capitulum The portion of the barnacle above the peduncle (shelled part) of a goose barnacle.
Carapace The hard dorsal covering of the head and thorax of the body. Does not cover the abdomen.
Carapace length The distance from the anterior most part of the head (usually the rostrum) to the posterior most part of the carapace (does not include the abdomen).
Carapace width In crabs, the distance between the lateral spines (the posterior most spines) of the carapace. This measurement is usually used to describe crab size.
Carina A raised ridge. In goose barnacles, an unpaired narrow plate adjacent to the paired scutum and tergum plates. One of the parietes in other barnacles.
Carpus The 3rd segment from the distal end of a crab leg. In a clawed leg, it is the segment where the appendage flexes (i.e. the elbow).
Cephalothorax The fused head and thorax of many crustaceans.
Chela (pl. chelae) The last two segments of a leg that forms a pincer or claw. It includes the movable and immovable fingers and the palm, except in mantis shrimps (no movable finger).
Chelate Possesses a chela (claw).
Chelipeds The 1st pair of legs (anterior most) when they have claws.
Cirrus (pl. cirri) Biramous appendages in barnacles used to filter the water for food.
Claw appendage The entire appendage that possesses a claw, from the fingers to the point of attachment to the body.
Concave Curving inward.
Convex Curving outward.
Crest of claws An elevated, irregularly toothed ridge
Crustacean An invertebrate with a segmented body, a hard external shell (exoskeleton), paired and segmented appendages and have 2 pairs of antennae. Includes shrimp, crabs, lobsters, barnacles and mantis shrimps.
Dactylus (dactyl) The segment of a crab leg that is most distal (farthest) from the body. In a clawed leg, it is the movable finger segment.
Distal Farthest from the center of the body.
Dorsal Pertaining to the top (back).
Dorsolateral Upper part of sides.
Endopod The inner pair of flattened appendages of the tail fan or at the end of a biramous segment.
Exopod The outer pair of flattened appendages of the tail fan or at the end of a biramous segment.
Eyescales Scale-like structure at the base of the eye stalk.
Fingers The parts of the claw that opposes each other, one being movable, the other stationary.
Hepatic spine Spine on the anterior lateral side of the carapace, behind and slightly below the eye orbit.
Immovable finger The finger of the claw that does not move.
Interorbital The edge of the carapace between the orbits (eye sockets)
Keel A ridge.
Lateral The sides of a body.
Lateral spine The spines on the outside edges of the carapace at its widest point (usually the posterior most spines on the sides).
Length of crab Usually refers to the carapace width. If a strong rostrum is present, length is sometimes reported as the carapace length.
Length of shrimp The distance from the tip of the rostrum to the tip of the telson.
Major cheliped The largest clawed appendage when the claws are unequal in size.
Manus In a clawed leg, the manus makes up the immovable finger and palm. The propodus.
Maxillipeds The three outer pairs of mouth appendages.
Merus The 4th segment from the end of a leg appendage.
Mottling Areas of color with no particular shape or pattern.
Movable finger The finger of the claw that is movable.
Nodules A small lump or knot.
Oblique Angled, either upward or downward, usually refers to mouths, stripes or lines.
Opercular plates The movable plates in the orifice of the shell in barnacles. Consists of the paired scuta and paired terga.
Orbit The eye socket.
Orbital teeth Projections or spines flanking each side of the eye socket.
Orifice The dorsal opening of the shell in barnacles.
Palm The part of the claw behind the movable and immovable fingers.
Paries (pl. parietes) A triangular plate on a barnacle.
Peduncle A fleshy stalk between the shell and substrate, in goose barnacles.
Pereopods In shrimp, the 1st 5 pair of long walking legs, attached to the cephalothorax, the 1st few of which may or may not be chelate.
Petasma Genital structures attached to the 1st pair of swimming legs in male penaeid shrimp. Looks like a pair of extensions, one from each leg with ends united together in larger shrimp.
Pleopods In shrimp, the paired swimming legs that are attached to the abdomen, usually biramous.
Posterior To the rear.
Propodus The second segment from the distal end of a leg. In a clawed leg, the propodus is the segment with the immovable finger and palm.
Proximal Nearest the center of the body or point of attachment to body.
Radius (pl. radii) The walls in between the triangular plates in barnacles.
Rostrum An extension of the carapace between the eyes projecting anteriorly.
Scutum (pl. scuta) One of a pair of internal opercular plates in barnacles (in goose barnacles, the lower external triangular plate).
Serrated Saw-toothed.
Setae (plural of seta) Small hairs
Spine A sharp pointed projection.
Stomatopod A marine crustacean with strongly toothed, scissor-like claws and have gills on their abdomen. Also called mantis shrimps.
Tail The abdomen, in shrimp.
Tail fan Two pairs of flattened appendages that attach to the last segment of the abdomen. Teeth
Telson The most terminal segment of the abdomen. Forms the center part of the tail fan.
Tergum (pl. terga) One of a pair of internal opercular plates in barnacles (in goose barnacles, the upper external plate).
Tergum spur A projection on the basal margin of the tergum in barnacles.
Thelycum External pocket on the underside of the thorax of female penaeid shrimp, used for receiving the male sperm sac. Usually covered by 2 lateral plates (absent in white shrimp).
Third maxillipeds The outermost part of the mouth appendages.
Thoracic segment A segment between the carapace and the abdomen in mantis shrimp. The last pairs of walking legs are attached underneath.
Thorax The part of the body between the head and abdomen.
Tubercle A calcified and hard protuberance.
Uropod Two pairs of flattened appendages that attach to the last segment of the abdomen.
Ventral Pertaining to the underside or bottom.
Walking legs Legs that are used for walking that do not possess a claw (except in shrimp, may be chelate.)