Download Chambered Nautilus - Cy

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Mollusks
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
Chiton
Chambered Nautilus
Assignments
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 Mollusk
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
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.
Squid
Read the definitions and the color and label the squid diagram below:
Arms - eight short limbs, each of which has two rows of
suction cups on the lower side; the arms hold the food
while the squid bites it into swallowable pieces
Feeding tentacles - the two, long tentacles are used for
obtaining prey; they have toothed suckers only near the
tip
Beak and mouth - the parrot-like beak on the mouth is
used for biting food into small pieces. The beak and
mouth are surrounded by the bases of the arms and
tentacles
Head - the small part of the body between the mantle
and the arms; the head contains the eyes, the brain, and
the muscular buccal mass, which crushes the food
Clubs - the ends of the tentacles, which have toothed
suckers
Mantle - the large part of the squid in front 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, very large
eyes; they are large in proportion to the size of the body
Siphon - a tube-like organ on the lower side of the head;
it expels water forcefully, 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)
mouth - on the underside of the head - it contains the radula, a
file-like tongue that breaks down the snail's food
foot - the soft, muscular part of the snail that
allows the snail to move (tan)
respiratory pore - a small hole in the side of the body, used for
breathing (green)
shell - the hard, spiral, protective covering of the tentacles - two long and two short sensory tentacles on the upper
snail (brown)
surface of the snail's head (Purple)
head - the front part of the snail, containing the
tentacles, eyes, and mouth (gray)
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 red-brown. 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:
1. Define visceral mass and tell what protects it.
2. Name mollusks (3) with a shell.
3. Name mollusks (3) without a shell.
4. The foot of cephalopods is modified into ________________.
5. How do aquatic mollusks breathe?
6. What opens and closes bivalve shells?
7. How do bivalves feed?
8. Give 2 defense mechanisms used by octopi.
9. How do squid and octopus move quickly away from predators?
10. What is the most intelligent mollusk?
11. What type of circulatory system is found in most mollusks?
12. Explain the circulatory system of cephalopods.
13. Do mollusks have complete or incomplete digestive systems? What distinguishes them as such?
14. Which class of mollusk is characterized by having a single spiral shaped shell?
15. Which class of mollusk has a dorsal-ventrally flattened body with 8 overlapping plates?