“I used to get the feeling they were watching me,” Anderson said as
he stood one recent night before the glass; a tentacled gray blob
was smooshed against it, and pair of black eyes peered out.
“This handsome young male we named Achilles."

Nighttime at an aquarium can induce all sorts of hallucinations.
Still, in any light, there are few life forms more homely or alien
– in both substance and appearance – than the giant Pacific octopus, or GPO.
Full-grown adults can weigh up to 400 pounds,
yet the entire pulsating mass of one can pass like water
through a drain pipe the circumference of a tennis ball,
about the size of the animal’s cartilaginous beak, its only solid part.
At rest, they look like discards from a leather factory;
in motion, the animal resembles a rapidly deflating hot-air balloon
with no one at home in the gondola but those two knowing black eyes.

“When you look at them,” Anderson said, lightly tapping
the glass above Achilles’s head, “you definitely get the feeling they’re looking back.”
A strict man of science and the son of an old-salt, Puget Sound sea captain,
Anderson isn’t the sort to anthropomorphize animals.
But he and his fellow aquarium workers were so taken with the personalities of their GPOs
that naming them soon became part of their responsibility as caretakers.
GPOs only live for three or four years, and the aquarium has regularly
kept three on hand – two on active display and a third “understudy octopus.”
So Anderson has known a good many octopi over the course of his tenure.
Still, he was able to readily recall all of them.
Lucretia McEvil, for example, regularly tore up her tank after closing hours;
she pulled up the rocks at the tank’s base, pulled out the water filter,
bit through water hoses, and left all the pieces floating
on the surface for the day shift to clean up.
Leisure Suit Harry was something of a molester,
always reaching out to grab people with his many arms.
Emily Dickinson, on the other hand, was a particularly shy
female octopus that always kept to herself, hiding behind the rock outcroppings in the tank.

Anderson went on. One GPO with wanderlust would repeatedly escape from his tank,
to be found the following morning eating the shellfish in a nearby exhibit or making
his way up the aquarium’s back exit ramp. Don Juan once tried to pull a pretty videographer
into his tank when she put her hand too close to him. He repeatedly wrapped his tentacles up and down
her arm faster than she could unravel them; when she finally managed to break free, Don Juan turned bright red
(GPOs change colors in accordance with their moods) and then doused the woman with the jets of water that octopi
normally use to propel themselves underwater. Still another temperamental GPO turned bright red when any worker attempted to clean his tank,
before then grabbing their cleaning tools and pulling them into his tank.

Scientists don’t readily ascribe emotions and personalities to animals.
But in 1991, Anderson decided to see if he could possibly codify in scientific terms whatever
it was that his GPOs seemed to be expressing. He and Jennifer Mather, a psychologist from the
University of Lethbridge in Alberta, Canada, conducted a personality study of the smaller red octopuses at the aquarium.
They borrowed three categories – shy, aggressive, and passive – from a standard human personality test.
They found that their subjects consistently clumped together into one of the three groupings
when responding to various stimuli – when a crab was dropped in the tank, for instance,
or one of their tentacles was touched with the bristles of a test tube brush.

“The aggressive type would go right after the crab,” Anderson recalled.
“The passive ones would hold back and wait for the crab to come their way before pouncing on it.
The shy ones would just huddle in a corner and wait until overnight, when no one was looking,
and in the morning we’d find this neatly stacked little pile of empty crab shells.”

In 1993 Anderson and Mather published their findings in the Journal of Comparative Psychology.
The paper, entitled “Personalities of Octopuses,”

was not only the very first documentation of personality in invertebrates. It was also the first time that
anyone can remember the term “personality” being applied to a nonhuman in a major psychology journal.
In 2003, their pioneering study became one of the cornerstones of a whole new field of scientific inquiry known as “Animal Personality,”
which now has its own institute located at the University of Texas in Austin.

Along with his octopus personality studies,
Anderson would go on to conduct a number of GPO intelligence tests. He said he was first awakened to their cleverness
in the course of testing the animal’s reactions when novel objects were placed in their holding tanks.
In one study, he put different colored plastic pill bottles in the tanks. Most of the subjects would grab the bottle
and bring it to their mouths to see if it was edible. Sometimes they’d just hold it at a distance,
then blow it away with their water funnels. But one day Anderson noticed one of his female octopi repeatedly blowing
the bottle into the tank’s water inlet valve. The stream from the valve would propel the jar back to the octopus,
which promptly blew it back toward the valve again, over and over, in a recurring cycle.

“I ran to the phone to call a colleague,” Anderson recalled, “and I shouted ‘She’s playing ball! She’s playing ball!’”

The revelation soon had Anderson devising enrichment toys for his GPOs to keep
them from getting bored in captivity. He devised octopus “play puzzles,” putting pieces of herring
inside of jars that they then must learn to open in order to retrieve their prize.
He put bits of herring inside of plastic Mr. Potato Head dolls that his GPO’s soon learned to open.
Some of the animals even learned to open childproof pill bottles. As for whether GPOs can recognize themselves in
the mirrors that he placed in their tanks, Anderson is skeptical.

“I didn’t see any real self-recognition,” said Anderson, who retired from the aquarium
two years ago and has just co-authored a book about his lifelong obsession, entitled Octopus, the Ocean’s Intelligent
Invertebrate. “But a couple of them did crawl up to the mirror to stick their eye
against the one in the reflection, like they were eyeball to eyeball with another animal.
What we have definitely shown in a recent study is that octopuses recognize individual humans.”

At one point in the course of our private nighttime tour,
Anderson led us around to the opposite side of Achilles’ tank to view the GPO next door.
Wedged there between a set of rocks near the adjacent tank’s outer glass was a female named Mikala,
with whom Anderson was hoping Achilles would soon mate. Finding her fast asleep, we turned to leave,
only to be met by the piercing stare of a glowing red Achilles.

“We like to think red signifies anger or stress for an octopus,”
Anderson said. “Or that white is fearful, or gray is sleepy, though we can’t really define what
an emotion is in an animal. Still, just knowing what we do now about them has made me a big proponent of enrichment for octopuses,
of finding ways to give them new and different experiences to keep them occupied.”
He added that, toward the end of their lives, the octopi are released, so they can return to the open sea.
“It’s the responsible thing to do.”