The tail of a sea scorpion has 1 needle. Sea scorpions are the earliest members of the family of hermit crabs, spiders and scorpions that are known to be extinct. The scientific name of the sea scorpion is the giant feather-winged horseshoe crab, which appeared in the Paleozoic Devonian about 400 million years ago. It often lurks in shallow water, looking for small fish, trilobites and other animals in sediments, and sometimes even the same kind. Sea scorpions are usually residents of the seabed, but they can also live in fresh water and land. Sea scorpions have a strong protective ability-armor covers their bodies and claws. They walk on eight legs, and there are two flat legs behind them. Once out of water, they will become clumsy. If they are underwater, they can swim a long distance.