of Animals Should I Expect to See in the Touch Tanks?
Most animals with shell "houses" to protect their
soft bodies are called mollusks. Oysters, clams, scallops,
and whelks are all mollusks. These animals have a mantle of
soft tissue inside the shell. The edge of the mantle secretes
calcium carbonate that turns to shell when it mixes with sea
are large snails that live in sandy areas. The soft body of
the whelk is protected by a heavy shell. The sharp edge of
this shell is used by the whelk to pry open clams to eat.
These animals have a head with eyes and two pairs of tentacles
that contain organs of feel, taste, and smell. The sharp file-like
tongue called a radula is used to cut or tear food.
Whelks also have gills that remove oxygen from the surrounding
Whelks move by means of a thick muscular foot pushed out of
the bottom of the open shell. The animal can withdraw the
foot and other body parts and close the opening with a trap
door called an operculum.
Snails have a single shell and are called univalves.
Clams have two shells and are called bivalves.
Clams and other bivalves are filter feeding animals that use
siphon-like tubes to draw water through an organ that traps
tiny plankton that the clam eats. Clams pull themselves through
mud and sand by means of a single wedge-shaped foot.
Oysters cement themselves to hard objects located
between the high and low tide water lines and are unable to
Scallops are the fastest bivalves. They rapidly
open and close their two shells like castanets and pulse through
the water to escape enemies.
The sea star or starfish is a spiny-skinned animal that has
from five to fifty arms or rays. The small spines projecting
through their skin cause these animals to feel rough. They
can grow new arms if one is injured or lost, though this process
may take weeks to complete.
Sea stars use the hundreds of small tube feet on their arms
to pull open a clam to eat. These tube feet are operated by
a hydraulic system using sea water. The mouth is located on
the underside of the animal.
The hermit crab is a crustacean and a close relative of the
shrimp, lobster, and blue crab. It has five pairs of legs.
The first pair of legs is claws, the second and third pairs
are used for walking, and the last two pairs are used to hold
the crab securely in its borrowed shell.
Hermit crabs live in empty mollusk shells that they find,
and as the hermit crab grows, it must find a larger shell.
The shell protects the crab's soft rear body parts.
Horseshoe crabs, which are more closely related to spiders and
other arachnids than to crustaceans, have lived on the earth
for millions of years. Although the horseshoe crab looks menacing,
it is harmless. Its long tail is used to turn itself over -
not as a weapon.
The horseshoe crab has jointed legs and an outer shell (exoskeleton)
of chitin that is shed periodically as its body grows.
It uses the front of its round shell to plow through the sand
to uncover worms and clams which it feeds upon.
Horseshoe crabs have copper in their blood which gives it a
blue color. Their blood is used in testing pharmaceutical products.
Spider crabs are found in a variety of habitats such as eel
grass beds and open sandy bottoms where they feed on scavenged
items. Their shell, which is covered with short curved hair,
frequently has algae, bryozoans, sponges, and barnacles growing
over it. The spider crab's shell may grow to four inches in
diameter; its leg span can measure up to one foot.
Portly Spider Crab
species of animals found in each of the the NC Aquarium
touch tanks varies seasonally.