- 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.
- Diet crustacean larvae, small copepods, detritus, diatoms, algae
- Size across (7.6 cm)
- The sand dollar has a rigid, flattened, disk-shaped test, or shell,
made of firmly united plates lying just beneath the thin skin.
- Small spines that densely cover the test enable the animal to burrow
in sand just below the surface.
- Like other members of its class, the sand dollar is radially symmetrical.
It also shows evidence of a secondary bilateral symmetry, i.e., the
mouth is centered on the oral (under) surface, but the anus lies near
the rear edge of the test.
- Tube feet are similar to those in other echinoderms and are used
for locomotion and to convey small food particles, mostly organic matter
found in sand, to the mouth. Tube feet on the upper surface are used
for respiration.
- More convex, short-spined sand dollars are called sea biscuits.
- Sand dollars are abundant on the sandy bottom of deeper waters on
both the Atlantic and Pacific coasts.
- They are classified in the phylum Echinodermata, class Echinoidea,
order Clypeastroida.
- They live on the sandy sea floor, from the intertidal zone (the area
between high tide and low tide) down to the subtidal zone (the area
below low tide).
- Most sand dollars are found at depths of 30 to 40 feet (9-12 m).
- Sand dollars partly bury themselves under the sand, with an edge poking
up out of the sand.
- Sand Dollars are eaten by sea stars (also known as starfish), snails,
and skates.
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