Transcript Octopus and Starfish

9. Octopus and Starfish
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An octopus is a mollusk that has no
shell at all
It looks as if it is all head and arms
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An octopus has eight (8) arms,
called tentacles, which have many
suckers on them
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Suckers hold on tightly to objects
they touch
The suckers help an octopus to
crawl and to hold on to its food
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An octopus moves by pulling itself
along by its tentacles
It can also use a kind of jet
propulsion to move
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It pulls in water through its gills and
sends it out very fast through a tube
under its head
The force of the water moves the
octopus backward
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One way that an octopus can find
food is by hiding among stones and
seashells on the ocean floor
The octopus can change its color
to match its surroundings
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Small water animals that swim by
usually do not see the octopus
The octopus can grab an animal
with its tentacles
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Most kinds of octopuses are as
small as a person’s fist
How do they escape bigger
animals that feed on them?
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An octopus can squirt out a liquid,
like ink, that blackens the water
The octopus then swims away
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Giant octopuses that live in the
Pacific Ocean have few enemies to
swim away from
These octopuses can grow to be
30 feet long
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Starfish live in all oceans
Fish is part of their name, but they
are not fish but invertebrates
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Starfish have a small central body,
with a mouth on the bottom side
Most starfish have five arms that
stick out from their bodies
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Other kinds have more than 25 arms
Stiff spines cover their bodies and
arms
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Starfish are often dull yellow or
orange but can be bright colors, too
They can be as small as ½ inch
and as big as 3 feet wide
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Starfish use their tube feet to move
These small tube feet are under
each arm
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Suction cups are attached to the feet
Suction cups help starfish to move
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Starfish eat animals, especially like
clams and other mollusks
A starfish catches a clam with its
arms
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The clam closes its shell to protect
itself
Using its tube feet, the starfish
forces the shell open a little bit
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Then the starfish turns its stomach
inside out and pushes it out of its mouth
It sticks its stomach into the opened
clamshell and eats the soft clam body
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Then the starfish pulls its stomach
out of the clam
and puts it back into its own body
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A starfish can grow new arms if its
arms are broken off
This is called regeneration
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In fact, if a starfish loses all its arms
but one and most of its central body
a new body and new arms will grow
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Starfish eat mollusks like clams and
oysters that are valuable crops for
fishermen
The fishermen may try to destroy
starfish by cutting them into pieces
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But the pieces grow into even more
starfish!
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