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The octopus is a mollusc
and belongs to the same group as snails, chitons, abalone, limpets, clams,
scallops, oysters and mussels. The octopus also belongs to a smaller group
of molluscs called the cephalopods, which means "head-foot"; it is so
named because its "feet" (arms) are attached to its head. Squid and cuttlefish
are also cephalopods. These molluscs have been roaming the oceans for
more than 450 million years.
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| squid |
cuttlefish |
 Octopuses
live in all the worlds' oceans but not in fresh water. They tend to be
small in warm tropical waters and larger in colder waters, such as the
North Pacific. The largest octopus in the world, the Giant Pacific Octopus,
lives in the coastal waters of British Columbia. The largest Giant Pacific
Octopus ever caught weighed about 270 kg (600 pounds) and had an arm span
of almost 10 metres (33 feet). But most are much smaller: females seldom
exceed 25 kg (55 pounds) and males average less than 40 kg (88 pounds).
 An
octopus has eight arms attached to the head around the mouth. Each arm
has rows of suckers along the length of its arms. The octopus has many
nerves in the arms and suckers; it can actually taste with its suckers.
The Giant Pacific Octopus has two rows of suckers per arm and may have
as many as 1,600 suckers in all.
The octopus has no
bones. The only hard part of its body is a beak made of a material like
your fingernails. The beak, located in the mouth, is used to kill prey
and bite it into pieces. An Octopus's bite is poisonous; the Blue-ringed
Octopus of Australia has killed humans by biting them when defending itself.
camouflage
 The
octopus has a well-developed brain and excellent eyesight. It can instantly
change the colour and texture of its skin to match its surroundings. This
camouflage is a major method of protection from predators.
jetting
backwards
 The
body of the octopus, called the mantle, looks like a bag and it moves
as the octopus breathes. Inside the mantle are the stomach and all the
other organs including 3 hearts. A heart at the end of each of the two
gills pumps blood through the gill and the third heart pumps the blood
through the body; Octopus blood is pale blue. When the octopus breathes
in, water flows over the gills and fills the mantle. When it breathes
out the water is forced out a tube call the siphon. If an octopus is trying
to escape a predator it can force water through the siphon rapidly and
jet itself backwards. Octopuses have been known to travel many kilometres
using jet propulsion. An octopus can also temporarily blind an attacker
by squirting ink at it.
Most octopuses live
only one or two years. The Giant Pacific Octopus is one of the longer
lived species: the female can live to about 3.5 years and the male to
approximately 4 years.
 A
female octopus will lay thousands of eggs and protect them until she dies.
The Giant Pacific Octopus lays about 50,000 eggs and tends them for about
6 months. During this time she does not eat but spends all her time protecting
the eggs from other animals such as sea stars and crabs. She will only
produce one nest in her life. When the babies hatch they are not giants
like their mother but about the size of a grain of rice. They rise up
to the surface layer of the ocean and stay there for about six weeks.
When they grow large enough to survive on the bottom of the ocean the
juvenile octopuses drift down again. It will take almost 3 years for them
to grow to be as big as their parents.
PART
2: Octopus Reproduction
PART 3: Jim Cosgrove's Octopus Adventures
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