ANIMAL BYTES
The giant Pacific octopus
is an intelligent creature.
In laboratory tests and
aquariums, it has been
able to solve mazes
very quickly,
unscrew jar lids to
retrieve food inside
the jar, and even
mimic another
octopus in a different
tank.
T
he devilish
h octo
octopus
topu
pu
us iss a p
predatory
reda
re
dato
dato
da
t ry
mollusc with
th a pouch-shaped
pouch
ch-sha
sha
h pe
ped
d body
body
bo
dy
and eight powerful
erful arms with two rows
of sucon discs on each. It also has an
ink sac, which it uses to darken the water
when it senses danger.
An octopus is basically a water-filled
balloon, but with the fluid contained in
muscle cells rather than an open cavity.
It keeps its shape not with an internal
or external skeleton but by hydrostac
pressure, somemes called a hydrostac
skeleton or muscular hydrostat.
Found worldwide in tropical and
warm temperate waters, octopuses are
related to squids, cu#lefish, nauloid, and
other molluscs such as snails, mussels and
clams. They can creep over hard surfaces
using their arms; when they travel through
water they move by jet propulsion, taking
in water and ejecng it forcibly through a
funnel as their muscular mantle contracts.
They vary in size from a few cenmetres to
the giant octopus of the Pacific Ocean that
can grow to over 10 m. Some species are
edible, including the ink!
The two large, complex eyes of the
octopus are camera-like in structure, and
their vision is acute. Much of their life is
spent in hiding, and many species choose
a natural hole among rocks or in a pile of
rubble. Small species, however, such as the
pygmy octopus, O. joubini, which is about 2
cm (about 5 in) long, may prefer an empty
clamshell having both valves sll connected
by a ligament; se#ling into one half, it pulls
the shell shut with its suckers.
The octopus lures its vicm by wiggling
the p of an arm like a worm; or it glides
near and pounces on a crab, sinking its
beak into the shell and injecng a poison
that kills; the poison of some species is
dangerous to humans. The prey is seized by
the sucker-bearing arms and pulled into the
web of ssue at the base of the
arms, paralyzed and parally
digested by a poisonous
salivary secreon, and chewed
Much of their life is
spent in hiding, and
many species choose
a natural hole among
rocks or in a pile of
rubble.
SCIENCE REPORTER, DECEMBER 2013
54
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The o
ctopus can change
ct
colours by contracng skin cells filled
with pigment. This ability also allows it to
camouflage itself when hunng for prey,
such as shrimp, crabs, scallops, abalones,
clams, and fish.
Octopuses are preyed upon in turn
by a number of fishes, including the
moray eel. When an octopus is a#acked,
it draws water into its mantle cavity and
expels it with great force through a funnel
propelling itself backwards. The result is a
jet-propelled exit, usually behind a cloud of
“ink,” a dark substance the octopus ejects
for defense. The ink of some species seems
to have a paralyzing effect on the sensory
organs of the predator.
Soon a.er mang, the female begins
to lay eggs, each enclosed in a transparent
capsule, in its lair, producing about 150,000
in two weeks. The female guards them for
the next 50 days, je2ng water to aerate
and clean them. The young float to the
surface and become part of the plankton
for about a month, then sink and begin
their normal life on the bo#om.
Octopuses generally do not live more
than one or two years. The giant Pacific
octopus lives longer than most octopus
species. Males live about 4 years and
females about 3.5 years. They usually die
a.er breeding.