Crabs are one of the oldest species on earth and they are generally found in
all the oceans and fresh water. Sometimes they live on land and sometimes several
miles from water. There are 4500 species of crabs living in this world. They
are also called decapods which mean 10 legs. About 850 species of crabs are
fresh water or (semi-)terrestrial species and they are found throughout the
world's tropical and semi-tropical regions.
Crabs have five legs and first pair among them is modified into a pair of
claws. Crabs do not have lungs so they breathe through gills. The size of a
crab varies from species to species. The biggest crab found in Maryland measured
9 inches. They are omnivores and most of the crabs are well known to be scavengers,
they eat dead or decaying material and can also intake any other food including
bacteria, fungi, worms, depending upon their availability and the crab species.
They eat edible wastes in the water. Crabs can also be predators. They eat
shellfish beds and seaweed. They will also eat snails, mussels and decayed vegetation.
For many crabs, a mixed diet of plant and animal matter results in the fastest
growth and greatest fitness. Sometimes crabs may feed on vegetable matter, and
others eat small living animals.
The crab lives their lives up to a maximum lifespan of 3 years. Crabs are
also known to be one of the nice swimmers. They swim with the help of swim paddles.
One of the interesting facts of crabs are they have their teeths in the stomach.
Humans catches crabs for eating and for medicine because of the fact that crabs
contain good amount selenium in them which is helpful against bacterial infection.
