Sand dollar
A sand dollar is a flattened marine echinoderm in the order Clypeasteroida, related to sea urchins and sea stars.
A sand dollar is a flattened marine echinoderm in the order Clypeasteroida, related to sea urchins and sea stars. The living animal burrows in sandy seafloors and feeds on small organisms and detritus; the white, coin-like objects found on beaches are usually the dried skeletons, called tests. The term also refers to several related species, with common names and ranges varying by region.
Description
Sand dollars are flat, disk-shaped echinoderms with a rigid skeleton and short spines when alive. Their distinctive shape gives rise to the familiar coin-like appearance of dead tests washed onto shore.
Habitat and range
They live on sandy seafloors, often in the low intertidal zone and shallow subtidal waters. The Monterey Bay Aquarium lists one species, Dendraster excentricus, as ranging from Alaska to Baja California.
Feeding and behavior
Sand dollars use their spines and tiny tube feet to move and to capture food particles. Their diet includes crustacean larvae, copepods, detritus, diatoms, and algae.
Taxonomy and relatives
Sand dollars are echinoderms in the order Clypeasteroida. They are closely related to sea urchins, sea stars, and sea cucumbers.
Key facts
- Sand dollars are flattened, burrowing echinoderms, not true shells.
- They belong to the same broad phylum as sea stars, sea urchins, and sea cucumbers.
- The visible beachcombing specimen is usually the animal’s skeleton, called a test.
- One well-known Pacific species, Dendraster excentricus, ranges from Alaska to Baja California.
- Sand dollars live on sandy seafloors and feed on tiny planktonic organisms and detritus.
Sand dollars occur along the Pacific coast of North America, so they are relevant to Canadian readers in British Columbia and other Pacific coastal contexts.[1]
Frequently asked questions
What is a sand dollar?
Are sand dollars shells?
Where do sand dollars live?
What do sand dollars eat?
How big do sand dollars get?
References
- Monterey Bay Aquarium — https://www.montereybayaquarium.org/animals-the-ocean/animals-a-to-z/sand-dollarSupports: Scientific order, habitat, diet, range, size, and relatives for a sand dollar species.
- WorldAtlas — https://www.worldatlas.com/articles/sand-dollar-facts-animals-of-the-oceans.htmlSupports: General definition of sand dollars as marine echinoderms and relation to other echinoderms.
- Wikipedia — https://en.wikipedia.org/wiki/Sand_dollarSupports: Common names and the fact that sand dollars refers to multiple species within the order Clypeasteroida.