The North American horseshoe crab (Limulus polyphemus) is common throughout the Chesapeake Bay. Adults are greenish tan to brown in color, roughly two feet long and one foot wide.
From late spring through early summer, horseshoe crabs converge on beaches during high tide to deposit their eggs. A single female can lay up to 100,000 eggs.
According to archaeologists, horseshoe crabs have existed for some 300 million years. These odd-looking creatures are not crustaceans, but belong to the arachnid (spider) family.
Limulus Amebocyte Lysate (LAL), a compound found in horseshoe crab blood, is an important pharmaceutical aid.