Looking at the shape of its outside shell, you can easily see
why a horseshoe crab (or Limulus polyphemus) got the "horseshoe"
part of its name, but what about the "crab"? People once thought
the horseshoe crab was a crab, but the animal is, in fact, more
closely related to the common garden spider than to a blue crab.
Horseshoe crabs, which feed upon worms, small mollusks, and
algae, are a living fossil; they have been literally unchanged
for the past 360 million years! Picture: Young naturalist
inspecting a horseshoe crab shell. The carapace was empty. If
this was a live animal, picking up by tail could cause injury to
the crab. Picture courtesy of Mary Hollinger, NODC biologist,
NOAA. To the original photo. When it is time to mate, sometime
in the early summer during high spring tides, which are
influenced by the full moon, the female horseshoe crabs will
come ashore. The males follow, often even hanging on to the
females' backs with special hooks in their first pair of legs.
The female horseshoe crab digs