Carolyn C. Smith
The box crab has enormous claws and he uses them to open the shells of mollusks. Once the box crab has caught the mollusk, he chips the shell until he has made a hole large enough to pull the animal out of its protective home. These large claws are also used to push sand forward to make a shelter. The box crab is also known as the bashful or shamefaced crab because when he wraps his claws around his body for protection it appears that he is hiding or being bashful. This particular species can sometimes be found in the deep waters of bays and sounds. They are plentiful along the Atlantic coast.
Male vs Female
It is very difficult to distinguish the male crab from the female crab because they look so much alike. If you were to examine them closely you will note that there is a difference in the shape of the shell, in the structure of their bodies, and in some cases the coloring. The abdomen of the female is usually larger and more oval or round shape while the male is a narrow triangular shape. This difference allows the female to protect her eggs. Among the green crabs, hermit crabs, and others, the male is larger than the female. The horseshoe crab is just the opposite wherein the female is usually larger than the male. The male blue crab has blue and white tips at the end of its claws while there are red tips found on the female. male fiddler crabs have one small and one large claw, however, both claws of the female are small. If you are ever able to watch the courting ceremonies of some crabs, you will note that the male is more aggressive than the female. (See Diagram Below)*
Male
(figure available in print form)
Female
(figure available in print form)
Life Span of Crabs
Although crabs have been around for millions of years, there is very little known about the age of crabs. However, it is believed that most crabs have a life span of about 1 to 2 years. Blue crabs are known to live for three years, mole crabs for two years, and the small pea crabs for two to three years. Dungeness crabs, caught and, sold along the Pacific coast, are reported to live for eight years. The king crab is believed to have a life span of about 10 to 14 years.
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There is evidence that these apecies who make their homes in the deep waters of the ocean have a tendency to live longer because they are better protected from man and other predators.
Conclusion
This unit has covered only the basic information concerning the physical characteristics, biological function, environmental behavior, and habits of crabs found throughout the world. There is no doubt in my mind that hundreds of years will go by before scientists are able to solve the mysteries surrounding these animals. This is conceived by the fact that their life span is too short for man to study their traits for any length of time. Also I have concluded that those deep ocean dwellers are too remote for man to study. I also perceive that the crabs will fall into the same category as so many other animals have been placed. That is that when and if they ever become extinct or an endangered species, their fossils will reveal to man what he has always questioned. Until that time we must continue to watch these animals and do what we can to extend their lives during this period in history.