Mystery of the Sea: National Geographic Pursues the Giant Pacific Octopus

April 19, 2010— -- Nicknamed the "devil fish," the giant Pacific octopus has a place in sea-faring lore alongside whirlpools and white whales. National Geographic went searching for this enigma of the deep, a giant who lurks in the shadows of the sea that has been known to grow up to 30-feet wide.

The oceans of planet earth harbor almost 300 different species of octopus, running a wide gamut of colors, shapes and sizes. They thrive in virtually every underwater habitat, from deep hydrothermal vents to shallow shores. But the giant Pacific octopus is the stuff of legend. Stories of freakish encounters with these creatures date back more than 50 years.

Although even the average giant Pacific octopus is very large, they are very hard to find. They can change colors to match the sea floor and, if that doesn't work, they have the uncanny ability to squeeze into the smallest of places. The only limitation to their incredible malleability is their small beak, found at the base of its eight legs.

"If the octopus can fit its beak through a hole, the whole animal can be squeezed through," says Jim Cosgrove, a marine biologist who has been studying octopus for over 30 years. "They are specialists in blending with their environment. What you need to learn to look for is what's called a midden heap, which [are] the remains of the octopus's meals. These are cast outside the den and consist of shells of crabs or snails or abalone or something like that."

However, this does not mean that a giant octopus needs to hide much to ensure its survival. Just one sucker on one of their tentacles can hold on to weights up to 35 pounds.

"Multiply that by 200 suckers, times eight arms, and you have an animal that is capable of supporting multi-tons," says Cosgrove. The suckers are also "chemotactic," meaning they can taste what they touch.

Even Cosgrove says he was afraid the first time he saw one of the giant beasts up close. "It was very much a fear fascination type of thing. I wasn't sure whether it was going to lunge out at me and suck the heart out of me."

National Geographic Pursues the Giant Pacific Octopus

Their diet consists mainly of crabs and snails, but in remarkable video obtained by National Geographic WILD, you can see they are not scared to do battle with a shark.

But for all their toughness, there is tenderness.

The National Geographic team filmed a site rarely seen: A female Octopus nursing her eggs -- one hundred thousand of them.

She will guard them for up to 11 months.

The process will take all of her strength, after they hatch, she will die.

And of the hundred thousand eggs that hatch, only two, on average, survive to become adults, and begin again -- the glide of devil fish.

Hunt for the Giant Octopus airs Tuesday night, April 20 on National Geographic Wild.