Octopus exhibit sucks people in

Octopuses don't recognize themselves in a mirror. But they can differentiate among people. In an experiment done by Roland Anderson, a biologist at the Seattle Aquarium, giant Pacific octopuses would rise to the surface to greet a researcher who had fed them in the past. But when a second researcher approached — one who'd touched them with a bristly stick — they squirted water on him.

It's that kind of intelligence, coupled with octopuses' alienlike appearance, that feeds the public's fascination with the animals, says Anderson. To celebrate the eight-legged invertebrates, the aquarium gives them their own week — Octopus Week — which started Saturday and runs through Saturday.

On Sunday, visitors crowded in front of the aquarium's new, 120,000-gallon tank to watch as two divers moved one of the aquarium's giant Pacific octopuses, Emrich, into a viewing tank. The divers kept Emrich close to them — for good reason. Let free, he'd likely make a meal out of some of the fish.

Anderson was behind the scenes, standing knee-deep in the tank above public view, helping make sure all went well.

The intelligence of the octopus captured his interest 25 years ago when he was first assigned to care for them. He also researches their behavior, mostly on his own time. It was that research, conducted with Jennifer Mather, a psychology professor at the University of Lethbridge in Alberta, Canada, that first documented that octopuses have personalities, and that they engage in an activity that can be classified as play. Their study of whether giant Pacific octopuses can recognize individual people will be published soon.

Along with Emrich, named for the person who bought octopus naming-rights at a fundraising auction, the aquarium also has three other giant Pacific octopuses. One is named Dolores Umbridge after the character in the Harry Potter novels because she's aggressive, Anderson says. And another, named Harry — after the boy wizard himself — is pretty easygoing.

"He's docile, compliant," Anderson says. "He does what we want him to."

The aquarium also has a number of the much smaller, red octopuses that grow to, at most, about a half-pound. The giant Pacifics are among the biggest octopuses in the world and can weigh more than 100 pounds.

As part of Octopus Week, the aquarium on Saturday released a giant Pacific octopus named Tank back into the wild. Each giant Pacific octopus is kept at the aquarium for about six months to a year, Anderson says.

Octopus Week also features an informal census of giant Pacifics in Puget Sound. Volunteer divers usually spot about 70, Anderson says, and he expects it will be the same this year.

One of the highlights of his career, Anderson says, was finding that giant Pacific octopuses could open childproof medicine bottles. It was long known they could open screw-top jars. So Anderson decided to give them a challenge. The first day, he said, it took them about an hour to open the plastic bottle and get the food inside. Within a week, he said, it took them just five minutes.

Octopuses are not as smart as golden retrievers, Anderson says, and probably not as smart as cats — or even rats. But they're smarter than most fish, he says, and many birds. And that's pretty impressive for an invertebrate.

Linda Shaw: 206-464-2359

or lshaw@seattletimes.com