Astriclypeidae
Astriclypeidae is a family of sea urchins in the order Clypeasteroida. They are commonly known as sand dollars, though that term can also refer to other closely related sea urchins. Astriclypeidae are characterized by their flattened, disk-shaped bodies with five-pointed symmetry. They are typically found in shallow, sandy bottoms in tropical and subtropical waters worldwide.
Characteristics
Members of the Astriclypeidae family are characterized by several distinct features:
- Flattened, disk-shaped body: This shape allows them to burrow into the sand and minimizes the impact of waves.
- Five-pointed radial symmetry: This symmetry is evident in the arrangement of their spines, pores, and other body parts.
- Five-pointed star-shaped pattern on the upper surface: This pattern is formed by the arrangement of their petal-like ambulacral areas.
- Mouth and anus on the underside: This arrangement is common in sea urchins, facilitating feeding and waste removal from the substrate.
- Short, blunt spines: These spines are adapted for burrowing and protection, unlike the longer, pointed spines of other sea urchin families.
Environment
Astriclypeidae species are found in a variety of environments, but they are most common in:
- Shallow, sandy bottoms: Their flattened bodies allow them to burrow into the sand for protection and feeding.
- Tropical and subtropical waters: They prefer warm, salty waters and are found in locations such as the Caribbean Sea, the Indo-Pacific, and the Mediterranean Sea.