Crab Facts

Crab Facts
Crab is an invertebrate that belongs to the crustacean family. There are over 4500 species of crabs and most of them live in the coastal areas of salty, fresh or brackish water (mix of fresh and salty water). Besides aquatic species, some crabs are semi-terrestrial or terrestrial (they live on the land). They inhabit sandy areas with stones and rocks. Crabs are very old creatures. They appeared on the Earth during Jurassic period, 200 million years ago. Certain species of crabs are endangered because of the habitat loss and due to intensive hunt. 1½ million tons of crabs are cooked alive each year. Latest analysis showed that crabs feel the pain during that process.
Interesting Crab Facts:
Crabs greatly vary in size. Smallest species, Pea Crab, reaches from 0.27 to 0.47 inches in length. Largest species, Japanese Spider Crab, has a leg span of 12 feet (from claw to claw).
Crabs are also known as decapods because they have 10 legs. First pair of legs is modified into claws, called chelae.
Crabs have external skeleton called "exoskeleton". It is made of chitin and it provides protection for the soft tissue underneath it. Other name for exoskeleton is shell or carapace.
Just like other Arthropods, crabs have segmented body (body divided in several parts). Unlike other animals - thorax and abdomen are fused together into a single unit called "cephalothoraxes".
Females can be distinguished from males by the shape of the abdomen and the flap on their bellies. Female has wide abdomen and flap shaped like a dome. Male has narrow abdomen and flap shaped like obelisk.
Crabs have eyes on the stalks, just like snails. They can distinguish colors, but their eyes see a lot less details than human eyes.
Crabs are omnivores (they eat both meat and plants). They eat different kind of algae, fungi, bacteria, other crustaceans, mollusks and worms.
Crabs walk and swim sideways.
Crabs breathe with the help of gills. That is why they need to stay close to the water even if they live mainly on the land.
Some species of crabs are solitary, while other live in the group. Collective name for the group of crabs is "cast".
Crabs which live in the group are very cooperative. They work together to provide food and protection for their families.
Crabs communicate via sound. They produce drumming and flapping sounds by using their claws and pincers.
Most crabs mate when the outer temperature and the temperature of water is high. Male waves with its swimming paddles, as a part of the seduction ritual prior to mating.
Pregnancy lasts one to two weeks and female deposits between 1000 and 2000 eggs.
Average lifespan of the crab is between 3 and 4 years.

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