Octopuses
are quite common in the coral rubble area but are shy and well camouflaged.
Some may be as large as 1m across with their arms outstretched, others
are tiny and less than 10cm across.
Deadly slug: The octopus is related
to snails and slugs, but it is a deadly predator. A predator's best
weapon is the a brain, and the octopus the smartest known invertebrate!
It has a well-developed brain and excellent eyesight. Studies show
that the octopus can learn, not only by itself but also from one another!
It has three hearts. Besides the usual heart, it has two additional
hearts, each pumping extra blood through the gills. Its blood is blue
due to concentrations of copper-based pigments that transport oxygen.
Octopus on the Hunt: Octopuses
are carnivorous hunters, searching for prey mostly at night. An octopus
on the hunt usually moves about slowly in the shallows with its many
arms spread out to feel into crevices for crabs, prawns, snails and
clams. The octopus has eight long arms with strong suckers to grip
prey and for moving around. The highly flexible arms also have numerous
receptors sensitive to taste and touch. Octopuses are even known to
travel short distances out of water! The arms are joined together
near the head with webbing that the octopus might use as a net. Sometimes,
an octopus may envelope a patch of rubble with this webbing to trap
any prey hiding there. The prey is usually killed with a bite of its
sharp beak, then brought back to the den for a leisurely meal.
Octopuses bite! Although octopuses
have a hard beak and a radula (ribbon of teeth), they don't chew their
food. Digestive juices are injected into the prey which soften the
tissues. Some can inject a toxin with their beaks. So please don't
touch octopuses. Some octopuses can drill a hole through a snail’s
shell to get at it. Others crush shells and crack crabs with their
hard beaks.
Shell-less but not helpless: Unlike
most other molluscs, the octopus does not have a shell at all. This
is not necessarily a disadvantage as the octopus can then squeeze
into all kinds of impossibly tight hiding places.
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The
octopus, however, also relies on stealth and speed to avoid
danger. An octopus can rapidly change its colours and even the
texture of its skin to blend with its surroundings. When spotted,
some octopuses change colours suddenly to confuse the predator.
They then zoom off using jet-propulsion.
When particularly alarmed, an octopus may release a cloud of
ink to disorient predators. The ink may contain substances that
affect the senses of other sea creatures. In the clouded water,
the octopus makes its getaway. This is also a handy way to disorient
prey. |
Octopus
babies: Octopuses have separate genders. The male has a
special arm called a hectocotylus that is used to insert a sperm packet
into the female's body. The female uses the sperm to fertilise her
eggs as she lays them. In most, the eggs are laid in capsules attached
to hard surfaces.
In bottom-dwelling octopuses, the female looks after her eggs; keeping
them oxygenated and free of algae and bacteria and defending them
from predators. Some even carry their eggs with them. The female does
not feed during this time and usually dies after the eggs hatch. Most
octopuses breed only once in their life, and many die after doing
so.
The eggs do not hatch into free-swimming larvae. Instead, miniature
octopuses emerge. Some are rather well-developed and settle down soon
after hatching. Others may drift with the plankton before settling
down. Here's a photo
of a baby octopus on Image
Quest 3-D Marine Library.
Human uses: Octopuses are widely
eaten in Asia. They are caught in many ways, including by lines, in
pots or by trawling. |
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What Suckers!
Whereizit?!
Octopuses change
colours to match
their surroundings
White Out
Octopuses may turn white to surprise predators
Out of water
Octopuses can
travel out of water
Octopuses on
Chek Jawa can
grow quite large
This octopus changed colours rapidly
Tiny 'pus! |
