Nature Study: Horseshoe Crab

On our recent trip to Cape Henlopen, Delaware, we picked up a Horseshoe Crab that had died and was left at the beach. The carapace was crushed. I don't know whether that was the cause of death or whether that happened after it had died. 
 It provided a wonderful opportunity to look at the Horseshoe crab in depth. A Horseshoe Crab has twelve legs; five pairs of walking legs and a set of tiny chelipes. The first four pairs of legs have claws at the tips and grinding joints where they join the body at the mouth. The grinders only work while the legs are moving, so the crab must walk to eat it's food; small mollusks, worms and crustaceans. The fifth pair of clawless legs is use to propel it along the bottom of the ocean or bay.
The long tail looks like a stinger of some sort, but it is not. It is used mainly for steering and for flipping the body over if it gets turned upside down. We had the opportunity to see this at the Cape Henlopen Nature Center when one of the Horseshoe crabs in their tank accidentally was flipped on its back.
 From our research, we found out that the horseshoe crab shell is ground up and used to make a dressing that protects victims of severe burns from infection. 
older student's nature journal page
 It's blood, copper based and so it is blue, has an element that may stop the growth of some cancer cells and can detect the presence of certain poisons and disease.

My journal page
 The female horseshoe crab crawls ashore to lay her eggs in the sand and then returns to the water.
student nature journal page, age 9
On its dome-shaped carapace, the horseshoe crab has four eyes. Two of the eyes are compound and are positioned high on the carapace so that it can see when it buries itself into the sand. The two simple eyes are on the front of the carapace.

sources:
  • Exploring Creation with Zoology : Swimming Creatures of the Fifth Day, Jeannie Fulbright
  • Awesome Chesapeake, David Bell 
  • One Small Square: Seashore, Donald Silver
  • Beautiful Swimmers, William Warner

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