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|There's Nothing Like It
The familiar exoskeleton (test) of a sand dollar—often found cast up on a beach—is white, with an obvious
five-pointed shape on the back. But a live sand dollar has a different look. Densely packed, tiny, dark
purple spines cover live sand dollars and hide the star design.
In their sandy seafloor habitat, sand dollars use their fuzzy spines, aided by tiny hairs (cilia), to ferry food
particles along their bodies to a central mouth on their bottom side. They capture plankton with spines and
pincers (pedicellariae) on their body surfaces. A tiny teepee-shaped cone of spines bunched up on a sand
dollar’s body marks a spot where captive amphipods or crab larvae are being held for transport to the
mouth. Unlike sea stars that use tube feet for locomotion, sand dollars use their spines to move along the
sand, or to drive edgewise into the sand. On the upper half of the sand dollar’s body, spines also serve as
In quiet waters, these flattened animals stand on end, partially buried in the sand. When waters are rough,
sand dollars hold their ground by lying flat—or burrowing under. In fast-moving waters, adults also fight the
currents by growing heavier skeletons. Young sand dollars swallow heavy sand grains to weigh themselves
The sandy seafloor seems to be barren—until you look closer. Diversity is low, but species concentration
is high. Sand dollars are usually crowded together over an area—as many as 625 sand dollars can live in
one square yard (.85 sq m).
Detritus and microscopic organisms settled on the sand provide food for scavengers and filter feeders—
like burrowing anemones. Above the sand, crabs scurry for food. Flatfishes, skates and some sharks hide
in the sand.
The sandy seafloor is a valuable resource and needs protection. Bottom trawling causes damage to
seafloor habitats and accidentally catches and kills tons of marine life every year. The good news is that
some states have enacted laws regulating trawling. Visit the Seafood Watch section on our web site to
learn more about trawling and choosing seafood wisely.
The sand dollar’s mouth has a jaw with five teethlike sections to grind up tiny plants and animals.
Sometimes a sand dollar “chews” its food for fifteen minutes before swallowing. It can take two days for the
food to digest.
Scientists can age a sand dollar by counting the growth rings on the plates of the exoskeleton. Sand
dollars usually live six to 10 years.
California sheepheads, starry flounders and large pink sea stars prey on sand dollars. When threatened
by pink sea stars, sand dollars bury themselves under the sand. Observers have seen a pink sea star
leave a wide path of buried sand dollars as it moves across a sand dollar bed
The Legend of the Sand Dollar
There’s a lovely little legend
That I would like to tell,
Of the birth and death of Jesus
Found in this lowly shell.
If you examine closely
You’ll see that you find here,
Four nail holes and a fifth one
Made by a Roman’s spear.
On one side the Easter Lily,
Its center is the star,
That appeared unto the shepherds
And led them from afar.
The Christmas Poinsettia
Etched on the other side,
Reminds us of His birthday
Our happy Christmastide.
Now break the center open
And here you will release,
The five white doves awaiting
To spread Good Will and Peace.
This simple little symbol
Christ left for you and me,
To help us spread His Gospel
Through all Eternity