Sand dollar is an animal that often lives slightly buried in the sand in shallow coastal waters. Its thin, circular body measures about 2 to 4 inches (5 to 10 centimeters) wide. Living sand dollars possess a fuzzy epidermis (outer layer) covering an inner skeleton. The epidermis may be brown, greenish, orange, or purple in color. Without the epidermis, the dried white skeleton somewhat resembles an old dollar coin, giving the animal its name.
The bodies of many species (kinds) of sand dollars contain slots. Sand moves up through the slots when the animal buries itself. A sand dollar uses tiny, movable spines to dig, crawl, and feed. The surfaces of the animal feature minute, soft extensions of the body called podia. The top surface has podia modified as breathing structures and arranged in the shape of a five-petaled flower. A sand dollar’s mouth lies in the center of its bottom surface. The animal eats tiny living things that it finds among sand grains or in the surrounding water.
To reproduce, female sand dollars release eggs into the water and males release sperm. Fertilized eggs develop into larvae (young), which sink to the ocean floor and grow into adults.
