12/11/13
Principles of Biology

Blue Crabs
When I think of blue crabs, I think of all the great tasting crustaceans in the ocean. After researching, I found that all crabs aren’t classified as crustaceans. They can be classified as a crab, true crab, or crustaceans. Blue crabs were listed as a true crab. The kingdom they belong to is the animalia. They have a Phylum and subphylum being the Arthropoda and crustacean. Arthropoda has the most numerous and widespread group of animals on earth. Arthropoda outnumbers 75 percent of all animals. Malacostraca is the class, while the order is the Decapoda and the infraorder is Brachyura. Portunidae is the family, which it belongs and the genus is the Callinectes. The species is C.Spadius. Now that I’m done speaking on all the King Arthur info we can move on to the things we might can pronounce. The crab’s physical appearance reminds one of an oversized spider. Blue crabs have 5 pairs of legs with the claws being called pincers. The claws are also one of the ways to determine if the crab is a male or female. Females have a very dominant red claw that is noticeable at a glance and the males have hints of red on the tips. The claws, points, and spines give the crab a menacing look. Claws can inflict some pretty bad wounds. The next 3 pair of legs are utilized for walking. If a crab loses a leg or claw, it is able to regenerate, or grow a new limb to replace the one lost. In addition, the crab possesses the power to throw off limbs voluntarily. If a crab is seized and held by a leg, it may release that leg and escape. The leg is regenerated during the next shedding cycle. The back legs are paddle like and assist the crabs in swimming. The legs coloration blue is why the crab is called the blue crab. The body is basically an olive green color. The body is a hard shell, so imagine the protection it gives. The crabs have eyes on moveable stalks and actually gives them a few advantages such as they have 360 degree vision and the ability to retract the eyes into grooves on it’s shell when danger threatens. Male crabs grow larger than female crabs. On there underside is another way to determine if the crab is male or female. Males have an apron on the abdomen that is sharply pointed and resembles the Washington Monument. Females have a rounded apron that is shaped like the capital dome. Juvenile females have a triangular apron. Females carry a mass of orange eggs on her underside, which is when she is said to be sponging because she is with child so to say. Crabs go through a process called molting in, which the interior of the crab is outgrowing the shell (exoskeleton). No it doesn’t grow along with it so it sheds. Some scientists call them peelers at this point. During the 48 hours, after the crabs shed, they become the softshell crabs we love to eat even though we’re allergic. At this point, crabs are defenseless without there shell. Females molt 18 to 20 times, not counting larval molts, in the course of a lifetime. Males are believed to go through the process 21 to 23 times. With both sexes the time between molts, which is called instar, gets to be longer ranging from 10 to 15 days for one-inchers to 30 to 50 days for legal hard-crab catch size and beyond.
Females can only mate after molting. Females must mate within minutes of molting. This mating was a little depressing to me. It is important to note that crabs will mate only when the mature female crab has just molted and is still a soft or buckram crab. believe that female crabs only mate once in a lifetime and male crabs get to be little players and mate all over the place. While the ordeal lasts from 6 to 12 hours it still a little unfair to me. When the females mate they can carry about 2 million eggs, but only a few may reach adulthood. Males make sure the females don’t miss their mating opportunity by cradling them prior. Males also cradle for a few days after mating for protection of the female.
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