Common name: sand dollar

General information

The Sand Dollar, scientifically known as Clypeaster subdepressus, is a species of sea urchins belonging to the family Clypeasteridae. These echinoderms are well-known for their distinctive flattened, disk-like shape and the pattern of flower-like petaloids on their upper surface. In life, they are covered with short spines that aid in locomotion and burrowing into the sand, but these are often absent in the bleached, white tests (skeletons) commonly found washed up on beaches.

Care

Sand Dollars require a sandy substrate in which they can burrow and sift for food. They are sensitive to water quality and require stable conditions with low nitrate levels. They feed on detritus, microalgae, and organic matter, so maintaining a mature tank with a well-functioning biological filter is essential for their health. They are not aggressive and can be kept with a variety of peaceful tank mates.

Reproduction

In the wild, Clypeaster subdepressus reproduces by releasing eggs and sperm into the water column, a process known as broadcast spawning. In the aquarium, breeding Sand Dollars is quite challenging and rarely occurs. If successful, the larvae will go through several planktonic stages before settling to the bottom and metamorphosing into juveniles.

Habitat

Sand Dollars are typically found in warm, shallow waters, often in sandy or muddy substrates. They are adept at burrowing and can often be found partially submerged in the substrate. In the aquarium, they require ample space to move and sift through the sand bed.