Glossary of Blue Crab Biology


apron  The crab abdomen, which is folded under the body.

Atlantic blue crab  Known by its scientific name Callinectes sapidus; in Greek "Callinectes" means "beautiful swimmer," and "sapidus" means tasty or savory.

backfin  The swimming or paddle fin. The rear-most fin of the crab, which is a flat, oval-shaped swimming fin. Also a type of crab meat.

buckram crab  A crab with a leathery, semi-hard shell, approximately 12 to 24 hours after molting; the stage past the paper shell stage.

buster  Crab in an advanced stage of molting, wherein the old exoskeleton (hard shell) has cracked under the lateral spines.

carapace  Top part of the shell of the crab.

Crustacea Class of invertebrates to which the Atlantic blue crab belongs; the crab is a crustacean.

dead man's fingers  The gills, elongated, spongy-looking organs. The term probably refers to the fact that the gray "shriveled" gills vaguely resemble the fingers of a dead person. They are not poisonous but do have an unpleasant taste and texture. Remove and discard when cleaning crabs.

doubler  Mating crabs; the male carries the soft-shell female crab, which has just completed its terminal molt, beneath it.

hard crab  Crab with a fully hardened shell, from about four days after molting.

jimmy crab  A male blue crab, distinguishable by its T-shaped apron. Regionally, the apron is said to resemble the Washington Monument.

megalopa (megalopae, pl.)  Final larval stage between the zoea and juvenile stage.

molt The process by which a blue crab grows larger by periodically shedding its smaller shell. Blue crabs are invertebrates, meaning they lack a spinal column. Instead, crabs have rigid exoskeletons (hard shells). The shell grows in discrete stages through molting, while growth of internal tissue is more continuous. Unlike male crabs that continue to molt and grow throughout their entire lives, females stop growing when they reach sexual maturity, usually after about 20 molts. During this terminal molt, mating takes place.

mustard  Yellow substance found inside a cooked crab. Contrary to popular belief, the "mustard" is not fat, rather it's the crab's hepatopancreas, the organ responsible for filtering impurities from the crab's blood. Although many find its flavor distinct and delicious, it is recommended that you do not eat this since many chemical contaminants concentrate in the organ.

paper shell  A recently shed crab, approximately 9 to 12 hours after molting. It has a slightly stiff shell, but is still considered a soft-shell.

peeler crab  Hard crab with a fully formed soft-shell beneath; it is ready to begin molting. Crab shedders can tell how soon a peeler will molt by looking at signs on the crab's shell that indicate two weeks (white sign), one week (pink sign), two days (red sign), or hours (rank peeler) prior to molt.

sally crab or she-crab  Immature female, distinguished by a triangular-shaped apron.

shed Either the empty shell or the process of casting off the shell.

soft crab, soft-shell crab  A crab immediately after shedding its old shell; its new shell is soft and pliable, and the crab is marketable as a soft-shell.

sook A mature female, distinguished by its bell-shaped apron. Regionally, the apron is said to resemble the dome of the nation's Capitol building.

sponge crab  Female crab carrying an egg mass.

terminal molt  The final molt, usually associated with the female. At the time mating takes place, she is in the soft-shell state and will not molt again after producing an egg mass. Males continue to molt throughout their lives.

zoea (zoeae, pl.)  The larva that hatches from the female crab's egg; multiple zoea stages are followed by the megalopa stage.

Drawings by Al Kettler

The information in this glossary was drawn from the sources below. For more about the blue crab, visit their web sites:
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