Daniel's Window

These creatures were once called "Horsefoot Crabs" because they looked like a horse hoof. The Horseshoe Crab isn't really a crab. It is related to scorpions, ticks and land spiders.

Horseshoe crabs have not changed very much in the last 250 million years. They have survived because of their hard, curved shells that protect their soft underbellies. The horseshoe crab has also persisted because it can go without eating for a year and survive changing temperatures and high salt content in the water.

Each spring during the high tides of the new and full moons, thousands of American horseshoe crabs descend on the shores of the Atlantic from Maine to the Yucatan.

Males, two-thirds the size of their mates, gather on the shoreline as the females arrive. The male holds on to the female's shell and is dragged up the beach to the high tide line. The male has glove-like claws on its first pair of legs that allow him to hold on.

The female stops intermittently to dig a hole and drop as many as 20,000 green eggs inside of it. The male then fertilizes the eggs as he is pulled over the hole. After this mating process is complete, the crabs leave and the waves wash sand over the nest.

Some Facts:

• Despite their size and intimidating appearance, horseshoe crabs are not dangerous.
• A horseshoe crab's tail, while menacing, is not a weapon. Instead, the tail is used to plow the crab through the sand and muck, to act as a rudder, and to right the crab when it accidentally tips over.
• The horseshoe crab's central mouth is surrounded by its legs and while harmless, it is advisable to handle a horseshoe crab with care since you could pinch your fingers between the two parts of its shell while holding it.
• Horseshoe crabs have 2 compound eyes on the top of their shells with a range of about 3 feet. The eyes are used for locating mates.
• Horseshoe crabs can swim upside down in the open ocean using their dozen legs (most with claws) and a flap hiding nearly 200 flattened gills to propel themselves.
• Horseshoe crabs feed mostly at night and burrow for worms and mollusks. They will, however, feed at any time.
• Horseshoe crabs grow by molting and emerge 25 percent larger with each molt. After 16 molts (usually between 9 and 12 years) they will be fully grown adults.
• Horseshoe crab eggs are important food for migratory shore birds that pass over the Atlantic shoreline during the spring mating season. Fish also eat the juveniles or recent molts.
• In the 1900s, horseshoe crabs were dried for use as fertilizer and poultry food supplements before the advent of artificial fertilizers.

A Horseshoe crab on the shores of Orchard Beach on April 26, 2008.