Mollusk habitats
and ranges...
Angelwing clam
Cyrtopleura costata
muddy bottom in shallow water
Chambered nautilus
Nautilus pompilius
around coral reefs and in waters
up to 1,650 feet deep
Atlantic bay scallop
Argopecten irradians
seagrass beds
Turritella
Turritella terebra
sandy mud in shallow water
Woody chiton
Mopalia lignosa
rocky intertidal zone and tide pools
Lightning whelk
Sinistrofulgar perversum
shallow water estuaries
This book belongs to
Every day, seashells wash up on beaches
all over Earth, like treasures from a secret world
beneath the waves. Spiraled or spiky, round or
ridged, shells come in all sorts of shapes and sizes,
and all the colors of the rainbow. Thats because
seashells have so many different jobs to do.
Seashells can rise and sink like a submarine...
A nautilus floats because most of its
shell is filled with a lightweight gas.
To dive down it pumps water into its
shell. When the nautilus wants to rise
toward the surface, it lets water flow
out of its shell.
gas chambers
water
or hold steady like an anchor.
spiraling shell
grips the sand
A turritella nestles into the soft, sandy
seafloor and filters tiny bits of food out
of the water washing over its body. This sea
snail can stay in one spot for weeks at a
time because its screw-shaped shell grips
its surroundings. The shell holds the little
mollusk in place.
Seashells can pry like a crowbar...
When a hungry lightning whelk spots a clam,
it climbs on top of its prey. The hunter slips
the edge of its shell between the two halves,
or valves, of the clams shell. Slowly, slowly,
the whelk pries the clams shell open. Then it
slurps up the soft, slimy animal inside.
or bore holes like a drill bit.
sharp ridges
To stay safe from predators, an angelwing
clam tunnels into the seabed. As the mollusk
spins in circles, the rough ridges on its shell
scrape and grind the sand, mud, and clay
around it. Over time the clam wears away a
burrow up to three feet deep.
Seashells can flit and flutter like a butterfly...
direction
of travel
water jets
A scallop spends most of its time lying on
the ocean floor. But when a predator attacks,
the scallop claps its valves together to propel
itself out of harms way. Some kinds of
scallops hop and zigzag across the ocean
floor. Others dodge and dart, or skim and
glide through the water.
or curl up tight like an armadillo.
Like a knights suit of armor, a chitons
shell has flexible plates that make it easier
for the mollusk to move. When a hungry
sea otter plucks a chiton off a rock,
the plates come in handy. They let the
mollusk roll itself into a ball to protect
its soft body.
chiton
armadillo
Seashells can let in light like a window...
Some areas of a heart cockle shell let sunlight
pass through. Thats good news for the tiny
algae that live inside the clams shell. Like
plants, algae need sunlight to make food.
Its also good news for the heart cockle
because it eats some of its tiny tenants.
or belch out waste like a ships smokestack.
All animals make waste material, and they
need to get rid of it. An abalones wastes
escape through a row of holes that runs
along one side of its shell.
holes
where
wastes
exit
shiny inside of abalone shell
Seashells can wear disguises like a spy...
thorny oyster shell without hitchhikers
The spines on a thorny oysters shell are the
perfect home for sponges, algae, and other
small creatures. As these hitchhikers grow on
the outer surface of the oyster, they hide its
shell from hungry hunters.
or hide in plain sight like a soldier in camo clothing.
A flat periwinkles shell matches the color
of the seaweed it lives on. This makes it
hard for enemies to spot the little sea snail.
Seashells can open up like your mouth...
When mussels feel safe they open
their shells and suck up tiny bits
of food floating in the water.
and close quickly like your eyelids.
But when mussels sense danger,
they snap their shells shut to
protect their soft insides.
head
sensory
tentacle
eye
foot
Seashells can send out a warning
like the signal from a lighthouse...
When a yellow-coated clusterwink senses
danger, it produces a flickering light.
The mollusks shell magnifies and spreads
the light, creating a green glow that tells
enemies to keep their distance.
crashing
breaking
eating
A tulip snails favorite food is other mollusks.
When it spots a tasty clam, it hurls itself at
the prey. Crash! Boom! Bang! The tulip snail
keeps slamming against the clam until the
clams shell shatters. Then the hunter slurps
down its meal.
Crash! Boom! Bang!
or smash other shells like crashing
waves against the shore.
But most of all, hard, strong seashells make
good homes. They protect like a fortress, keeping
mollusks safe in their underwater world.
Kinds of Seashells
Many ocean animals have shells, but the word seashell usually
refers to the hard covering that protects a mollusk. A mollusk
is a soft-bodied, legless animal. Many mollusks move around
on a muscular foot. The five largest groups of mollusks are:
Bivalves
Clams, mussels, oysters, and scallops are
all bivalves. Their shells have two halves, or
valves, that can open and close. Some bivalves
burrow in the sand. Others attach themselves
to hard surfaces. Most bivalves filter tiny bits
of food from the water.
Cephalopods
Squids, octopuses, and cuttlefish are all cephalopods.
But the nautilus is the only cephalopod with a shell
on the outside of its body. All cephalopods swim
through the sea in search of prey.
Chitons
A chitons shell has eight overlapping plates.
Chitons live in shallow ocean water. They
crawl along the rocky bottom, grazing on
algae and sponges.
Gastropods
Gastropods, or snails, are the largest group
of mollusks. Most snails have a coiled
shell. They can live in the ocean, in fresh
water, or on land. They eat a wide variety
of foods.
Scaphopods
A scaphopod, or tusk shell, has a long, tube
shaped shell that is open at both ends. These
animals burrow into soft areas of the ocean
floor and catch tiny creatures with their
threadlike tentacles.
Authors Note
The idea for this book popped into my mind when I saw Sarah S. Brannens gorgeous
sketches for our book Feathers: Not Just for Flying . On the final page a boy is running
along the beach as gulls soar overhead. I imagined that boy shifting his attention from the
birds above him to the seashells scattered along the sandy shore, and then heading off on a
new voyage of discovery. I connected with that boy because, in many ways, he was me.
Ive been fascinated by shells since childhood, when I spent summer vacations beachcombing
on Cape Cod, Massachusetts. As an adult Ive explored beaches all over the world, from Costa
Rica and the Galpagos Islands to Hawaii, Great Britain, and Kenya. I began my research for