|
Related to spiders and scorpions, the horsehoe crab(Limulus polyphemus) has changed little in 300 million years. Once there were hundreds of species of these trilobite-like creatures, but only four remain today. The Delaware Bay is home to the largest population of spawning horseshoe crabs in the world.
Every March, warming waters stir the crabs from the depths of the Delaware Bay and Atlantic Ocean to the sandy coastlines of Delaware and New Jersey. At the high tides of the full and new moons, female horseshoe crabs come ashore to lay their eggs. Waiting at the tide line, each samall male grabs hold of a female's shell. The female digs a shallow nest in the sand and lays up to 20,000 small, olive-green eggs. Next she drags the male over top to fertilize the eggs. Then they cover the eggs with sand and return to the water. After two weeks, the 1/8 inch-long juvenile crabs hatch, dig to the surface, and head for the water. Fedding on tiny worms, clams and dead fish, the miniature adult crabs continue to grow and molt until they reach sexual maturity at age nine or ten. Adult females measure up to two feet long and can weigh 10 pounds. Males are one-third the size of females. While it is not known how long a horseshoe crab can live, a few have survived 15 years in aquarium habitats. You can Take a close look at horsehoe crab.
| |
|
|