Blue Crabs Essay, Research Paper
The scientific name given to the blue crab was derived from Latin and Greek:
Calli, beautiful; nectes, swimmer; and sapidus, savory. Thus, a literal
transition might be the beautiful savory swimmer.
The blue crab is an important and interesting species. The blue crab is
a species whose life history involves a complex cycle of planktonic, nektonic,
and benthic stages which occur throughout the marine environment in a
variety of habitats. The blue crab is one of the more abundant estuarine
invertebrates and supports important commercial and recreational fisheries
along the Atlantic and Gulf coasts. The blue crab plays an important role in
the marine food web, providing prey for many species and a predator on other
species. The blue crab is a highly prized commodity to consumers.
Eight species of Callinectes have been documented in the Gulf of
Mexico: C. bocourti, C. danae, C. ornatus, C. exasperatus, C. marginatus, C.
similis and C. rathbunae, and Callinectes sapidus.
The original range of the blue crab is from Nova Scotia and throughout
the Gulf of Mexico to northern Argentina. The blue crab is rarely found north
of Cape Cod, but has been recorded in Maine and Nova Scotia. The blue crab
has been introduced into Europe, North Africa, and Southwest Asia.
Introductions into the Mediterranean Sea and surrounding waters have
produced breeding populations whereas others were probably temporary
occurrences. The blue crab also has been introduced into Japan.
Blue crabs are one of the most common marine invertebrates and are
generally abundant throughout the oceans. Peak abundance of adult crabs
occurs during the warmer months. During winter, crabs are found in areas of
tidal exchange in the lower estuary. Juvenile blue crabs are most abundant in
waters of low to intermediate salinity during the winter months.
Males become sexually mature at the 18 or 19th molt but may continue
to grow and molt an additional 3-4 times thereafter. Female crabs were
initially thought to rarely, if ever, molt again following their mature molt.
However, mature females undergoing a second molt have been verified.
No data on maximum age of blue crabs is available from the Gulf of
Mexico, although it has been estimated to reach a maximum age of 4 years in
Florida and 7-8 years in Chesapeake Bay.
Autotomy (voluntary breaking of appendages) and regeneration are
common in blue crabs. One survey found that 19-25% of blue crabs were
either missing or regenerating a limb. A functional appendage is formed by
regeneration following the next molt, although three molts may be required
for 100% limb regeneration.