| Size |
Adults can grow up to 9 inches. |
| Habitat |
Blue crabs are distributed throughout the U.S. Atlantic and Gulf coasts. Blue crabs
can be found in freshwater areas where salinity is 0 to the ocean where the salinity is
full strength (32+ ppt). Males are often found in the upper reaches of the Bay
while females are typically found further downstream and down-Bay where salinities are
higher. Submerged aquatic vegetation (SAV) areas are important nursery habitats for
juvenile blue crabs for two reasons: 1) SAV provides refuge from predators. Crabs that are
molting are less likely to be spotted and eaten in SAV than in
shallow marsh areas with no SAV. 2) SAV provides a large abundance of
prey. |
| Reproduction |
Mating occurs from June to October in the mid-Bay regions. Females still soft from
molting, mate with males. Males stay behind to spend the winter in the muddy bottoms of
the Bay. Females migrate towards the mouth of the Bay to release the fertilized eggs
(750,000 to 8 million eggs) that are developing in her apron. Newly developed eggs are
usually a golden orange but later turn black as the eggs near hatching. Females can be
found near the mouth of the Bay from May to October when small zoeae larvae begin to hatch
from the eggs. After a series of molts, the second larval form, the megalopa, is produced.
Because of the megalopa’s appearance, it is often mistaken for a tiny crayfish or
lobster. The megalopa begins to move along the bottom while making its migration further
up the Bay. During this migration, several more molts occur. With each molt, the megalopa
slowly transforms into the identifiable shape of a blue crab. When the crab reaches 12 to
16 months, it is approximately 5 inches and is ready to mate. Blue crabs generally only
live for 3 years. |
| Feeding |
Adult blue crabs generally feed on clams, soft-shelled crabs, SAV, fishes,
oysters and
anything else they can successfully capture or scavenge. They will even eat other blue
crabs that are still soft from a recent molt! Blue crab larvae and post-larvae probably
feed on rotifers, worm larvae, copepod nauplii and adult copepods. |
| Predators |
Small fishes and jellyfishes feed on the larvae. Larvae are often consumed by grass
shrimp (Palaemonetes pugio), sand shrimp (Crangon septemspinosa), juvenile
blue crabs and juvenile fishes. Adults are consumed by American eels (Anguilla rostrata),
striped bass (Morone saxatilis), Atlantic croakers (Micropogonias undulatus),
cobia (Rachycentron canadum), red drum (Sciaenops ocellatus),
black drum (Pogonias
cromis), oyster toadfish (Opsanus tau), sandbar sharks (Carcharhinus
plumbeus), bull sharks (Carcharhinus leucas), cownose rays (Rhinoptera
bonasus), speckled/spotted trout (Cynnoscion nebulosus),
weakfish (Cynoscion
regalis), catfish (Ictalurus spp.), gars (Lepisosteus spp.),
largemouth
bass (Micropterus salmoides), loggerhead turtles (Caretta caretta), Atlantic
Ridley turtles (Lepidochelys kempi), herons and egrets (family: Ardeidae), various
diving ducks and raccoons (Procyon lotor). |
| Description |
Blue crabs have a brilliant blue color on their front claws (tips are red on females)
with an olive or bluish-green carapace. They have a pair of paddle shaped legs that are
excellent for swimming. Crabs can also be identified by the nine marginal teeth behind
each eye, with the last pair of teeth ending in a sharp spine. |
| Additional Information |
Saving the Blue Crab |
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