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Beautiful
swimmers
The blue
crab is well-known to many who live near the Chesapeake
Bay. When asked about what they know about the blue crab,
most respond "it tastes good!" In fact, tasty
is part of the blue crab's name.
The
scientific name of the blue crab is callinectes sapidus.
'Calli' means beautiful (as in calligraphy - beautiful
writing) and 'nectes' means swimmer. And blue crabs
are referred to as the beautiful swimmers. That leaves
us with 'sapidus' which means tasty. So, scientists
knew what they were talking about when they named it!
And
here are some more names. Large, mature female crabs are
called sooks, and large males are called jimmies.
Picture:
Blue crab shedding
its shell.
Growing
pains...
Crabs
belong to a class of animal called Crustacea, which
includes lobsters, shrimp, and crayfish. Because their
shell is hard and doesn't grow with them, these crustaceans
must shed their shells in order to grow.
This
process is known as molting, and a crab will molt many
times during its life. A crab that is ready to molt is
commonly called a peeler, and the discarded shell is called
a slough. The soft crab's shell will harden again within
72 hours.
Male
or female_
Differentiating
between a male and a female blue crab takes nothing more
than turning the crab over (but watch out for the claws!)
and looking at its apron. The male crab's apron is long
and thin; the adult female's apron is rounded, and the juvenile
female has an apron shaped like a triangle.
Picture:
Drawings of
the aprons of an adult male, adult female, and juvenile
female.
Crab
research
Because
the blue crab is such an important resident of the Chesapeake
Bay, and because it plays such an important role (both
as a predatory species and as an object of prey), scientists
have made the blue crab a subject for research.
At
the Smithsonian Environmental
Research Center
in Edgewater, Maryland, Researcher Anson (Tuck) Hines
and his CrabLab have been studying the blue crab for many
years. One of its projects is to investigate the roles
of predatory fish and crabs in shaping estuarine communities.
Dr.
Hines tracks blue crabs in their wanderings by attaching
small radio transmitters to their backs and listening
for their signals. This "tag" transmits a signal
through the water at a certain frequency (similar to a
radio signal) which is then picked up by an underwater
hydrophone and a receiver. Reed switches and magnets attached
to the claws of the crab connect when the claws are extended
in a meral threat display and change the tag's signal,
allowing the scientists to record fighting events among
crabs, even though they cannot see them. By studying the
lifestyle and habits of the blue crab, scientists are
better able to understand their interactions within this
complex world.
Picture:
Scientist Tuck
Hines (with earphones) and his colleague listening for
blue crabs.
Next
time you bite into that crab cake, think about what the
blue crab has given up to give you that great meal!
References
and further reading
For
more information about blue crabs and research by scientists
at the Smithsonian Environmental
Research Center,
explore the Tales
of the Blue Crab
website based on a presentation by Mark Haddon. The website
includes many great photos and lots of information.
For
interesting photographs and lots of other information
about the blue crab, visit the Blue-Crab
Archives.
Also
visit the Blue Crab
HomePage
which, besides many more interesting facts about the blue
crab, has a section on internet links for more information.
