Crabs live in oceans, in fresh water, and
(44)
on
land, particularly in tropical regions. They are generally covered with thick shells. They have a single pair of claws. Crabs vary in size, from a few milimetre wide (the pea crab) up to 4 meters (Japanese Spider Crab). About 850 species of crabs live in freshwater. They can live on land in tropical (45)
and
semi tropical regions. Male crabs often have a broader, rounded abdomen. Crab (46)
usually
walk sideways. However, there are also some crabs that walk forwards or backwards.