The horseshoe crab is found along the coast of the western Atlantic from Maine to the Yucatan. The largest population is in the Delaware Bay region where tens of thousands of adults congregate to spawn on sandy beaches every spring. Many species of shore birds stop to feed on these eggs during their annual migration from South America to the Arctic.

• The blood of the horseshoe crab is blue because it contains copper.
• An extract of its blood is used to test the purity of vaccines and other pharmaceutical products.
• The horseshoe crab’s mouth is located on its underside amongst its five pairs of legs.
• This animal has ten eyes: two compound eyes on its back and eight others distributed throughout its body and tail.
• Because of its hard armored shell, the shark is the horseshoe crabs’ only predator.

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