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a report on Sand dollars

Posted by jonathan on September 26, 1998 at 06:56:45:

In Reply to: Re: Sand Dollars posted by kathy on July 02, 1998 at 19:58:38:

Sand dollars are a type of Echinoderm. The Sand dollar is related to the starfish, brittle stars, feather stars, sea cucumbers, sea lillies, and sea urchins. About 13,000 are fossils, and there are about 6,000 living species know. All echinoderms have unique features. Some features of the sand dollar are that they are mostly round. The sand dollars use the short spines on them to burrow into the ground. Just like any type of animal, the sand dollar, when alive, is covered with skin, and muscle tissue. Also sand dollars have suckers which are fueled by water pressure. The suckers help the sand dollar slide into the sand to get away from predators. These suckers also help the sand dollars slide food to their mouths. Sand dollars have a male and female sex, but they cannot be recognized from there outside features. The surface of the sand dollar appears to have petal patterns, which are really tube feet used for respiration. These tube feet combines with mucous-coated cilia, and it catches food that is favored by the sand dollar. Some of these favored foods are cod and haddcock. The sand dollar likes to mainly feed on small worms and algae. The sand dollars eat the food by consuming it on the underside of itself, and with a set of five teeth, chew and swallow its food. These mouths are much like a bird beak because it can be used to scrape things like algae off of rocks. Sand dollars reproduce through pores. Spawning adults shoot out clouds of eggs or sperm. The eggs are fertilized by the moving currents. They develop into tiny swimming larvae. After a month the larvae sink to the bottom, and then start to grow a protective shell. Sand dollars only live on very sandy beaches. They live in crowded beds with many other sand dollars. They are also found off the coast of Georgia. The sand dollar has many preditors. Sand dollars have no way to protect themselves, except for camoflouging themselves in the few inches of sand they are under. Their main predators are starfish, birds, otters, flounder, crustaceans, and octopus. Sometimes crabs cause some damage because they nip at the sand dollar, and with their claws. Sometimes the crab will eat or attack the sand dollar, and then left alone to die. Sand dollars also die from heavy storms. When severe storms hit, sand is shifted all around, which can bury a sand dollar in 12 inches of sand. This disables the sand dollar, and it cannot escape. Another mass mortality is from high temperatures. Sand dollars can survive in water that is 95°F for only three hours.
One type of sand dollar is called the keyhole urchin, or the keyhole sand dollar. It is related to a normal, plain sand dollar. On the keyhole sand dollar, there are 5 shaped slots that look just like a keyhole. This feature gives the keyhole sand dollar its name. The skeleton is rarely found on some beaches. Once the tan urchin dies, the spine will fall off, and the skeleton is bleached white. Many times dead sand dollars are found but they are chipped. These urchins, just like other sand dollars, live on the tide line where they can burrow deep into the sediment.
You can find dead sand dollars on the beach after they have been washed ashore. People, for hundreds of years, wear the fossil of sand dollars as jewelry, or use them in various arts and crafts.


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