Octopuses live large in the myths and legends of seafaring peoples around the world.
Some, like the Nordic Kraken, were ship-sinking sea monsters. In the Hawaiian creation story, the octopus is an alien that survived from a previous universe. And Akkorokamui, a sacred spirit in the Shinto religion, eats its own leg. Then it grows a new one.
Octopuses, more than any other animal group, invite imaginative “myth-interpretation.” They’re big-eyed, multi-armed, soft-bodied, superstrong, shape-shifting, color-changing, and venomous, with intelligence that can match wits with us. Alien as they might seem however, octopuses are homegrown, dating back at least to the Earth’s Upper Carboniferous period, about 296 million years ago.
At least one octopus legend is based in fact: Several species can break or bite off an arm at a predetermined fracture point as a survival behavior. The lost limb will regenerate, right down to the tip’s tiniest sucker, good as new.
But even tales of Kraken pale in comparison to more talents and traits of real octopuses.
Octopuses are standouts among invertebrates for their large brains. They can navigate mazes, solve problems, remember faces, predict, use tools, and take apart just about anything, showing equal facility at cracking a crab shell and picking a habitat lock. At aquariums, they’re quick studies with positive-reinforcement training.
An octopus can perform an array of tasks simultaneously thanks to a large nerve cluster, like a "minibrain," at the base of each arm independently controlling its movement. The more than 2,000 individually moving suction cups are equipped with chemical sensors that not only feel, but taste and smell as well. So while an octopus concentrates on hunting, its arms are moving it forward, testing the water and ocean floor, probing coral crevices, and maybe even prying open a clam already caught.
Octopuses have blue blood, not from royal genes, but from copper. Octopuses have a high metabolic rate, and therefore a high demand for oxygen. Copper-based hemocyanin is more efficient for transporting oxygen at the ocean’s low temperatures and low oxygen concentrations than is the iron-based hemoglobin that makes our blood red.
Octopuses have three hearts: two just to pump blood through the gills and one more to circulate it to the organs. The circulating heart stops beating while an octopus swims, which explains why these cephalopods prefer crawling—swimming exhausts them.
Sometimes, however, you’ve got to move fast. Many octopuses are able to escape danger by releasing a squirt of obscuring ink as they zoom away on a jet of water. For good measure, the ink contains a compound that burns predators’ eyes and temporarily paralyzes their senses of smell and taste.
All octopuses are venomous, although only the little blue-ringed octopus of Australia is dangerous to humans. Injected as an octopus drills into its prey with its beak, the venom fatally paralyzes an animal that could otherwise injure the squishy invertebrate in a struggle.
It Came from the Tide Pool
During short nocturnal forays ashore at low tides, a few coast-dwelling species hunt for easy pickings like crabs, shellfish and, according to some reports, harbor rats.
Octopuses Came from Chicago?
The oldest known fossil of an octopod was found at the famous Mazon Creek deposit, about 66 miles southwest of Chicago. It dates back 296 million years. The exquisitely preserved impression shows the arms, funnel, eye, beak, and possibly an ink sac. While living octopuses continue to be represented in Chicago at Shedd Aquarium, the oldest octopus so far resides at the Field Museum. And the newest is at the MCA—until Takashi Murakami: The Octopus Eats Its Own Leg closes on September 24!