In the video collage, the first small crabs with one claw are fiddler crabs. Males have very disproportionate claws. One, as you can see is large, and the other one is underdeveloped. There is also one female crab with two small claws in the video. The males move their large claw like playing a fiddle. They also use claw movement for communication, like you see in the video. If the large claw is lost, the small one can grow as well, but only during next growth cycle. They live in tidal waters, like mangroves. Fiddler crabs live only about two years. Females choose males for their claw size. A large claw is not only a sign of strength and good health, it also helps to make a good burrow for egg incubation.
The large crabs at the video end are terrestrial, or land crabs. There are many species of land crabs, but the distinction is somewhat blurred since majority of them return to water at some time, to lay eggs for example. They can either stay close to water or migrate inland and then back to the shore. One of the land crabs, coconut crab is the largest invertebrate on land. Land crabs live in dug out holes, or burrows. They eat what they can find around burrows, leaves, fruits, insects and meats if it is available.
Available stock video