For years the giant octopus was feared as a monster of the deep. But in reality it is a highly intelligent, resourceful animal that is quite harmless to humans. The giant octopus is a highly developed mollusk that has very acute senses, excellent mobility, and remarkable mental agility. It is so well adapted to its marine environment that many zoologists consider it the pinnacle of evolution among invertebrates.

Habits: The giant octopus spends most of its day lurking in a rocky crevice. It emerges at night to forage for prey. The site of its hideout is frequently marked by the shells and fragments of its victims – crabs, clams, cockles, and sea snails. If it does venture out, the octopus usually crawls along the sea floor, often with surprising speed. Buoyed up by the water, it may walk on “tiptoe,” pushing itself along with the tips of its powerful tentacles. Or it may glide along, propelled by a jet of water thrust out of its gill chamber. If it is alarmed, it can escape at high speed, jetting backward with tentacles streaming. Its soft body lets it squeeze through small openings.

Breeding: The male octopus is easy to distinguish from the female – one of his tentacles has no suckers near the end. He mates by inserting this tentacle into the female’s mantle cavity. A sperm package is propelled down a tentacle groove into the female’s oviduct, where the sperm fertilize her eggs. The male octopus dies soon after mating. The female may produce up to 100,000 eggs, which she strings up on the ceiling of her lair. She watches over the eggs for six months, never leaving the nursery or eating. Each egg hatches into a tiny octopus only a quarter of an inch long, which immediately swims off to join the plankton. It settles on the seabed and begins to grow at an amazing rate – from a weight of half an ounce to two pounds or more within seven months. Meanwhile the mother has died, exhausted by the effort of breeding and starved by the six-month vigil she kept over her eggs.

Defenses: Enemies of the giant octopus include seals, sharks, and larger giant octopuses. Its main defense is its speed and its ability to squeeze into tiny cracks and crevices. It can also confuse an attacker by squirting it with a dense cloud of ink. Nerve-controlled color cells in the skin let the octopus change color for camouflage or an intimidating display. As a last resort it will bite. If these defenses fail and the octopus loses tentacles in an attack, it simply grows new ones.

Food and Hunting: The giant octopus eats almost anything it catches, but crabs and bivalve mollusks are its main prey. It hunts mainly by sight and has eyes that have a lot in common with ours. The octopus surges forward and envelops prey with its tentacles. It checks the catch with its suckers, which have touch sensors and chemical receptors, and it will reject anything that feels or tastes wrong. Sometimes the octopus paralyzes its victim with a shot of venom from its salivary gland. But usually it rips prey apart with its powerful suckers. The octopus kills crabs with a shell-crushing bite from the parrotlike beak that is concealed at the center of its radiating tentacles. Then it scoops out the crab flesh and dumps the shells outside of its lair.

Key Facts: Sizes, Breeding, Lifestyle, and Related Species:
Sizes:
Tentacle span: Up to 30 ft.
Weight:  Up to 600 lb. Studies indicate a trend toward larger individuals in deeper water.

Breeding:
Sexual maturity: About 1 year. Male matures at a smaller size than female
No. of eggs laid: Up to 100,000
Hatching time: 6 months

Lifestyle:
Habit: Solitary. Lives on the seabed
Diet: Crabs, mollusks, and occasionally fish
Lifespan: Averages 3 years

Related Species: The giant octopus is a distant relative of garden snails and slugs. Closer relatives include other octopuses,
squids, and cuttlefish.
Distribution: Found along the coasts of the northern Pacific, from California to Alaska and west to the Sea of Japan.
Conservation: The giant octopus is vulnerable to pollution. But unlike its edible relative, the common octopus, it is not in direct danger from humans.

Special Adaptations of the Giant Octopus:
Suckers: Suckers are used to rip prey apart and to anchor the octopus to a rock. Sensors surrounding each sucker allow it to reject anything that tastes or feels wrong.
Tentacles: The octopus has eight strong arms. They are capable of pushing and pulling and can grip prey very tightly.
Siphon: The siphon, or funnel, takes in water. The octopus can use it to propel itself through water.
Beak: The giant octopus uses its powerful beak to crush crab shells.

Did You Know:
A giant octopus can live out of water for some time if it stays cool and damp. It may leave the water to search for food on land.
The giant octopus has the largest brain of all the invertebrates. It has a very good memory and can learn quite complex tasks.
Although the octopus has three hearts, they are not very efficient. Because it has poor stamina, the octopus cannot sustain a struggle for a long period of time.