During our week at the beach in the Gulf Shores area of Alabama, we did a lot of looking for shells. Tropical Storm Debbie just off shore in the gulf brought in huge waves and lots of shells, seaweed and other interesting things. However,the power of those huge waves crushed many of the shells into pieces so we didn’t find a lot of complete large shells. Among the broken shells on the shore, we,also, found many pieces of sand dollar skeletons.
Related Post: How Waves Affect Beaches
We searched and searched for a whole sand dollar skeleton, but never found one. However, our searching wasn’t in vain. On the last day of our time on the beach, my daughter was digging in the sand in about 3 feet of water and came up with this live sand dollar!
We could see and feel the spines moving as we held it in our hands. These spines help the sand dollar move and bury itself in the sand. Unlike the smooth sand dollar skeletons, the live sand dollar looked kind of fuzzy.
Sand Dollar Anatomy
Sand dollars are Echinoderms, as are starfish and sea urchins. Like other members of this group, sand dollars have 5 fold symmetry. You can easily see this in their 5 rows of pores shaped like petals in the top of their body. Tube feet line these pores to perform gas exchange (to breathe).
The mouth of the sand dollar is located in the middle of its underside. Tiny particles of food from the water or sand gets trapped in the spines of the sand dollar and then moved toward the mouth by small hairs called cilia. To learn more about the structure of a sand dollar, check out this sand dollar anatomy printout at Enchanted Learning.