The New Childrens Encyclopedia

Marine invertebrates

Huge numbers of invertebrates live

in the sea. Some, such as corals and

sponges, live fixed to the spot, but

others, including jellyfish and squid,

drift in midwater. Starfish and crabs

creep and scuttle on the seabed

everywhere from sunlit shallows

to pitch black depths.

OCTOPUS ANATOMY

Octopuses belong to a group of mollusks

called cephalopods, thought to be the

smartest of all invertebrates. Some

cephalopods have an external shell, but

in others the shell is internal. Most of

an octopus’s organs are inside its head,

including its digestive system and gills.

 MOUTH The octopus’s mouth

is a stretchy circular opening.

Inside is a sharp beak made of

horn, used for tearing up prey.

The octopus’s eight arms

bear rows of suckers that

grip onto rocks—and also

onto prey.

 ESCAPE An octopus releases

ink over a potential threat.

 OCTOPUSES

generally crawl on the

seabed, but also use

arm movements and a

form of jet propulsion

to swim in open water.

O

Size Body: 6¼ in (16 cm); arms 32 in (80 cm)

O

Location Indo-pacific region

Unlike most other octopuses this

animal hunts by day, using changing

body patterns to disguise itself. Its

preferred foods include clams, shrimp,

crabs, and fish.

Day octopus

Octopus cyanea

TAKE A LOOK: COLORFUL CHARACTERS

Octopuses can change color rapidly,

adopting different patterns to

communicate emotions and to

camouflage themselves on the

seafloor to avoid predators. If the

camouflage doesn’t work, they squirt

out a jet of ink. Hidden in the

cloud, they can escape from danger.

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LIVING WORLD