Horseshoe Crabs Essay

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Horseshoe Crabs Despite its common name, the horseshoe crab is more closely related to spiders and scorpions than crabs. All are invertebrates from the phylum Arthropods, or arthropods. This group of animals includes insect’s spiders, scorpions, ticks and mites crabs, lobsters, shrimp and barnacles and the 4 world-wide species of horseshoe crabs. Horseshoe crabs are one of the world’s oldest animals. For over 300 million years (at least 100 million years before there were dinosaurs on earth) horseshoe crabs have survived and remained fairly unchanged. The horseshoe crabs biology. Adult horseshoe crabs live in deeper water and come to shore to mate and lay eggs. Peak spawning occurs in New York in May and June, mostly during the evening high tides of new and full moons. After at least two weeks and up to several months later, the eggs hatch. The crabs also leave behind billions of eggs. More Horseshoe crabs come ashore on the beaches of Delaware Bay than anywhere else in the world. As some crabs leave, more arrive. That means eggs in the earlier nests are often dug up as later crabs make their nests. These eggs dry out and won't hatch. The extra eggs don't go to waste, though-not at all! They become part of an enormous egg feast. You see, horseshoe crabs aren't the only ones traveling to these beaches. At the same time, huge flocks of hungry birds are making a great journey of their own. These baby horseshoe crabs look just like an adult except that they do not have a tail and their eyes and digestive system are not yet fully developed. And they are small – only 3 mm across. It takes 9 or 10 years for horseshoe crabs to become adults. Ten Legs and Ten Eyes Under a horseshoe's bowl-shaped shell are ten spidery legs. As the crab walks along the ocean bottom, it digs up its favorite foods: worms and clams. But how does it eat with no teeth? With help from its

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