Mollusks (continued) Cephalopods Name means “head-foot” Most have no external shell

Mollusks (continued)

Cephalopods

• Name means “head-foot”

• Most have no external shell

A. Appearance of Cephalopods

1. Has a head (called a mantle)

2. Have tentacles

3. Most have a streamlined body shape

B. Eating in Cephalopods

1. At the center of the mouth there is a beak (-Used to crush hard organisms such as crabs & lobsters)

Caribbean squid beak

C. Movement in Cephalopods

1. Most are very good swimmers (-use jet propulsion)

1. Take water into the mantle cavity

2. Squeeze mantle shut3. Forces water out of the siphon4. This pushes the cephalopod

forward

D. Misc. Characteristics of Cephalopods

1. All are carnivores2. Have excellent vision (all

senses are well developed)3. Are most intelligent of

invertebrates (animals without backbones)

I. Cephalopods: The Octopus

A. Appearance of the octopus

1. Have 8 tentacles (or arms)2. Have suction cups on

tentacles3. Head is called the mantle4. Have no bones

Giant Pacific Octopus

B. Protection in the octopus

1. Can change its color with special color cells (called chromatophores)

2. Shoots out a dark ink to distract and cover its scent

3. Can swim very fast for short distances (like sprinting)

C. Reproduction in the Octopus

Blue spotted Octopus

1. Female may lay as many as 45,000 eggs

• Once the female lays eggs, she protects them

2. Female does not leave eggs, does not eat

3. After eggs hatch, the mother dies.

II. Cephalopods: The Squid

A. Appearance of the squid:1. Has 10 arms –2 are

longer, called tentacles

2. Have large eyes3. Have 2 fins to help it

swim4. Have an internal shell

called a pen

B. Protection in Squid

1. Use the same methods as octopus (they swim faster than the octopus)

Squid Mating Video(2:05)

C. Misc. Squid facts

•Swim in schools•Are known for their speed•Giant squid can be as large

as 56 feet and 3 tons (the eyes are the size of dinner plates!)

Bioluminescence in squid:

The mystery squid of the deep…

III. Cephalopods: The Cuttlefish

A. Appearance1. Can range in size from 1 to 2 feet2. Have 8 arms and 2 long tentacles (like squid)3. Shell is inside the mantle (or head) called the cuttlebone

B. Movement in the Cuttlefish

1. Cuttlebone has small chambers that fill with gas and water

2. Uses this to regulate buoyancy

C. Misc. Cuttlefish facts

1. Has ink and changes color for protection

2. Only lives about 18 months3. Uses the 2 tentacles as

“decoy worms” to catch food4. Females die shortly after

spawning

IV. Cephalopods: The Nautilus

A. Nautilus Appearance

1. Has a circular Outer shell (similar to the snail)

2. Has 38 to 90 tentacles

B. Nautilus movement

1. The shell is divided into 36 chambers

2. Each chamber can be filled with air for buoyancy (like cuttlefish)

3. Uses jet propulsion to go distances (like the octopus)

C. Misc. Nautilus facts

1. Are considered “living fossils” (are over 500 million years old)

2. Have poor eyesight3. Can pull their bodies inside the

shell like a snail4. Are very rare and little is

known about them