The B-movie title is appropriate: this is natural history that borders on science fiction.
Thirty-five million years ago (recent history in geological terms), crabs emerged from the sea to invade the land, and in that short time have adapted in the strangest of ways.
Land crabs can be found in the deserts of Australia, far from any water, imitating their neighbours the marsupials by keeping their young in specially developed brood pouches. In Florida, crabs have evolved such highly organised social groups that their mass annual migration to the spawning grounds closes local roads.
And they're getting bigger. The giant robber crab, terror of Christmas Island, can sever a human finger with its giant claws. For the invading crabs, this is just the beginning.

See This Week Page 15