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Mollusks Read And Color
The mollusks are members of the large and diverse phylum Mollusca, which includes
a variety of familiar animals well-known for their decorative shells or as seafood. These
range from tiny snails, clams, and abalone to larger organisms such as squid, cuttlefish,
chambered nautilus, and the octopus (the most intelligent mollusk). The vast majority of
mollusks live in marine environments, mainly on the coastal plains. However, two groups,
the bivalves and the gastropods, also contain freshwater species, and only the gastropods
have representatives that live on land (snails and slugs).
Chitons
Chitons are mollusks that along ocean coastlines in most of the world, but some
species have been found in deep water. They creep along slowly on their muscular feet
and cling to rocks. Chitons have shells made up of overlapping plates. The shell is divided
into eight plates embedded in the tough muscular girdle that surrounds the chiton's body.
Label and color the girdle tan and the plates dark green. This arrangement allows chitons
to roll into a protective ball when dislodged and to cling tightly to even irregular
surfaces.
Chambered Nautilus
The Chambered Nautilus is the best known species of nautilus. The spiral shaped shell,
when cut away, reveals a lining of shiny mother-of-pearl. The nautilus has primitive eyes
compared to other cephalopods, mostly due to the fact that they have no lens. It has
about 90 tentacles and NO suckers which is also different from other cephalopods. This
nocturnal animal has a pair of rhinophores, which detect chemicals and uses smell to find
its food. Color the shell sections of the nautilus tan and brown.
Cephalopod Mollusks
Octopus
The word octopus means "eight feet." Octopi (plural form) are solitary animals
with arms or tentacles that have suckers. They live on the ocean floor. There are over
100 different species of octopus. The Giant Octopus is the biggest octopus. This huge
mollusk is up to 23 ft (7 m) from arm tip to arm tip, weighing up to 400 pounds (182 kg).
The smallest is the Californian octopus, which is only 3/8 inch (1 cm) long.
An octopus has a soft body (visceral mass) and eight arms. The soft body is covered by a
protective layer called the mantle. Label and color the head and mantle dark blue. Each
arm has two rows of suction cups. If it loses an arm, it will eventually regrow (regenerate)
another arm. Label and color the arms gray and the suckers pink. It has blue blood. An
octopus has an eye on each side of its head and has very good eyesight. Label and color
the eye yellow. An octopus cannot hear. Octopi eat small crabs and scallops, plus some
snails, fish, turtles, crustaceans (like shrimp), and other octopi. They catch prey with
their arms; kill it by biting it with their tough beak, paralyzing the prey with a nerve
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poison, and softening the flesh. Color and label the beak red. They then suck out the
flesh. Octopi hunt mostly at night. Only the Australian Blue-ringed octopus has a poison
strong enough to kill a person. Octopi live in dens, spaces under rocks, crevices on the sea
floor, or holes they dig under large rocks. Octopi pile rocks to block the front of their
den. The den protects them from predators (like moray eels) and provides a place to lay
eggs and care for them (a mother octopus doesn't eat during the entire 1 to 2 months she
is caring for her eggs). In order to escape predators, an octopus can squirt black ink into
the water, allowing the octopus to escape. Another defense that octopi have is changing
their skin color to blend into the background, camouflaging them. The octopus swims by
spewing water from its body through a siphon, a type of jet propulsion.
Read the definitions and the color and label the squid diagram below:
Arms - eight short limbs, each of which has Feeding tentacles - the two, long tentacles
two rows of suction cups on the lower side;
are used for obtaining prey; they have
the arms hold the food while the squid bites toothed suckers only near the tip
it into swallowable pieces
Beak and mouth - the parrot-like beak on
Head - the small part of the body between
the mouth is used for biting food into small
the mantle and the arms; the head contains
pieces. The beak and mouth are surrounded the eyes, the brain, and the muscular buccal
by the bases of the arms and tentacles
mass, which crushes the food
Clubs - the ends of the tentacles, which
Mantle - the large part of the squid in front
have toothed suckers
of the head; inside the mantle are the
stomach, gills, ink sac, pen, reproductive
organs, and many digestive organs
Eye - an organ used to see; squids have two, Siphon - a tube-like organ on the lower side
very large eyes; they are large in proportion of the head; it expels water forcefully,
to the size of the body
enabling the squid to propel itself through
the sea
Fins - two flaps on the mantle that are used
to stabilize the squid during swimming
Gastropod Mollusk
Read the definitions and the color and label the land snail diagram below:
eyespots - located at the tips of the
long tentacles on land snails (red)
foot - the soft, muscular part of the
snail that allows movement (tan)
shell - the hard, spiral, protective
covering of the snail (brown)
head - the front part of the snail,
containing the tentacles, eyes, and
mouth (gray)
mouth - on the underside of the head - it contains
the radula, a file-like tongue that breaks down the
snail's food
respiratory pore - a small hole in the side of the
body, used for breathing (green)
tentacles - two long and two short sensory
tentacles on the upper surface of the snail's head
(Purple)
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Bivalve Mollusk
Clams are animals that burrow under the sea floor. They are bivalves, mollusks that
have two shells that protect a soft body. The oldest and highest part of the clam shell is
called the umbo. Label the shell and the umbo. The clam's shell is laid down in rings. The
rings close to the furthest from the umbo are the newest. Label and color the rings redbrown. The biggest clam is the Giant Clam is up to 4.8 feet (1.5 m) long and weighs up to
550 pounds (250 kg). Most clams are only a few inches long. Clams come in many colors,
including shades of brown, red-brown, yellow, cream, etc. The two shells are attached by a
muscular hinge and open and close with the help of an adductor muscle. Label and color
the muscular hinge orange. When a clam is threatened, most clams will pull their soft body
into the shells and close the shells tightly for protection. The foot is used to burrow into
the sand. The foot can be extended outside the shells or valves. Color and label the
foot light blue. Clams use their tube-like siphon to draw in water, from which they extract
oxygen and filter plankton (tiny plants that they eat.) Clams have both an incurrent and
excurrent siphon for water to enter and leave. Label and color the siphons pink. The
neck and soft body are at the base of the siphons. Label the neck and soft body.
Questions: Answer on Binder Paper and Attach to your coloring WS.
– Use your textbook, including the Table on Pg. 334, to help.
1. Define visceral mass and tell what protects it.
2. How do aquatic mollusks breathe?
3. What structure does the foot become in Cephalopods?
4. What is a radula and how does it work?
5. Name 5 mollusks with a shell.
6. Name 4 mollusks without a shell.
7. How does a chiton protect itself?
8. How does the chambered nautilus find its food?
9. What opens and closes bivalve shells?
10. How can you determine the age of a bivalve?
11. How do bivalves feed?
12. Give 2 defense mechanisms used by octopi.
13. What extremes does a mother octopus go through for her young?
14. How do squid and octopus move quickly away from predators?
15. What senses does an octopus have? What does it not have?
16. Explain what a trochophore and veliger are. How are they similar and
different?
17. How do cephalopods communicate? How are chromatophores involved?
18. Explain the circulatory system of mollusks.
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