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Tuesday, May 25, 2010

Horseshoe Crabs with Kids!

Activity:
After checking the moon phases and the tide schedule we found a good day to go to a beach in Delaware to see the horseshoe crabs. These are amazing creatures that spawn on the beaches of the Delaware Bay every year around the full moon and high tide. There are a few weeks you can see this fabulous display of survival. The Crabs lay their eggs in the sand and then the Red Knots (bird that fly from South America to the Arctic every year) come and feast on the eggs before continuing their flight north. This is a wonderful display of nature and we really enjoyed our day.

Education:

There are a lot of great facts and fun things to learn about
  these creatures. Matthew was enthralled and is planning on creating a presentation and looking up a lot of facts to elaborate on what we saw today. Not only was it an educational day but a FUN day!

Horseshoe Crab Facts and Figures
• 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 Delaware Bay 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.
• The medical profession uses an extract from the horseshoe crab's blue, copper-based blood called lysate to test the purity of medicines. Certain properties of the shell have also been used to speed blood clotting and to make absorbable sutures.

Links:
Video to watch from PBS called Crash: Tale of Two Species (The story of an ancient invertebrate and a little shorebird) http://www.pbs.org/wnet/nature/episodes/crash-a-tale-of-two-species/introduction/592/

http://www.ceoe.udel.edu/horseshoecrab/

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