This Humboldt squid is a preserved
specimen five feet in length. William
Gilly can study small squid in captivity,
but the Humboldt must be
studied in the field or preserved;
they don't live long in a lab.

Late in the afternoon, William F. Gilly, a professor of biology at Stanford University, lugs his equipment across the dirt-topped wharf. A stubble of beard pushes through the sunburn on his cheeks. He is a happy man. Why shouldn't he be? Free of the introspection of the laboratory, he's off to tag the wild Humboldt squid on the Sea of Cortés.

After packing his truck at Stanford's Hopkins Marine Station, in Pacific Grove, California, Gilly drove 900 miles without sleeping to Santa Rosalía, in Baja California, Mexico. Down the long peninsula, where the cacti troop to the indigo sea, past the lava fields and boulders and "pale, burned mountains" that fascinated John Steinbeck. In 1940 the novelist sailed with a marine biology expedition to the Sea of Cortés, or the Gulf of California. It is October 2001, and Gilly is leading a team of seven researchers on an expedition there. He turned 51 on September 11, a birthday well left behind. At Santa Rosalía the heat has slipped below 100 degrees, and the fishy air of the harbor is tickled with marijuana smoke, for the strangers have attracted a small crowd. The Mexicans are curious to see the scientists who, according to the posters they had put up in town, will pay fishermen $50 for each Humboldt squid that is turned in with a yellow tag in its mantle.

Gilly is an electrophysiologist, an expert on the wiring of the nervous system. Ordinarily the test subject for his research is the eight-inch-long squid Loligo opalescens, which seafood lovers know as the market squid. At Hopkins he studies the function of the giant axon, a thick, five-inch-long nerve fiber that triggers the squid's escape mechanism. The axon sends a signal to the muscle cells of the mantle, where a powerful contraction expels water from the squid's internal siphon, jetting the animal forward or backward. During the last 25 years in the lab, Gilly has penetrated ever smaller domains of the squid neuron, into the cell and down to the conductive protein molecules on its membrane, and from there to the genes responsible for producing those proteins. Now, in an abrupt shift of scale that also represents an abrupt career turn, he finds himself launching an uncontrolled experiment in the open ocean on an invertebrate creature that can reach six feet in length and weigh 60 pounds—the Humboldt squid.


The Sea of Cortés is the gash formed when Baja California split away from the Mexican mainland. For a narrow body of water it is extremely deep. Within the vertical volume of the sea swarm marlin, sailfish, red snapper, grouper, yellowfin tuna, sweet-tasting mahimahi, and groups of Humboldt squid.

The Humboldt, or jumbo flying squid, is one of the largest squid that anyone has seen alive. (So-called giant squid are much larger but are known only from rare, dead specimens.) Fast growing and short-lived, the jumbos move up through the food chain rapidly, so that at two years of age, which is as old as they get, only the biggest fish and the toothed whales can prey on them. But before then most have become meals in the cafeteria of the eastern Pacific. Squid may have become even more important to the food chain in recent years, Gilly notes, since aggressive fisheries have depleted the marine species with backbones. There are indications that squid populations worldwide are increasing, as they move into the niches opened by the harvests of finfish.

Squid are brainy mollusks. They once had shells and were relatively immobile, but in the grand battle of evolution, says Gilly, "squid had to give up their heavy armor and become free-swimming predators with vertebratelike eyes and big brains. They had to outsmart and outperform fish, which are more agile and explosive and maneuverable. The giant axon system is one solution for escape response and, probably, prey capture." He pauses and arches his eyebrows. "I often wish that I had a giant axon system to help me escape from certain people and situations—but also for jetting over and getting closer to others."


The region's main squid fisheries
are at Santa Rosalía and Guaymas.
Mexican fishermen haul in
110,000 tons of Humboldt
squid each year.

Image provided by ORBIMAGE,
© Orbital Imaging Corporation,
and processing by NASA
Goddard Space Flight Center.

From spring to fall the port of Santa Rosalía hosts a small-scale but intense fishery. Men race their fiberglass skiffs out onto the flat sea at night. They turn on battery-powered lightbulbs in an effort to lure schools of squid. With jigs—cylindrical lures ringed with hooks—they snag the reddish animals 500 feet down and pull them up hand over hand. The meat of the mantle is processed onshore and exported, most of it to Asia.

Gilly is here on behalf of the Census of Marine Life, an ambitious multi-project attempt to record the diversity and distribution of as many of the world's ocean creatures as possible. The goal of this part of the census is to mount electronic tags on large Pacific fauna like tuna, sharks, whales, elephant seals, sea turtles, and now squid. The lightweight devices track the animals in their migrations across the ocean. Some tags communicate directly with satellites; others store their data until the animal is caught again or comes ashore.

From the marriage of microelectronics and telemetry a new line of marine studies has been born. Gilly has hired two fishermen and a panga, as the 20-foot skiffs are known. While the fishermen catch the squid, Gilly and his young assistants will tag and release them. This is a preliminary experiment, in that the costly electronic tags won't be used. Gilly wants to learn how many marked animals will be turned in if the fishermen who catch them are offered a $50 reward. If enough tags come back, the data-logging "archival tags" will be deployed next time. Thus the marker is a ring of yellow plastic with a phone number printed on it (an 800 number in Mexico), along with a reward message. A fisherman turning in a tag is asked to report when and where the squid was caught.

The Sea of Cortés is dark. Mars is aloft, glowering red like the jumbo squid below, and a sweet breeze is blowing from the desert. Less than five minutes after the panga's anchor is set, the first squid is hooked. In their New York Yankee baseball caps and yellow rain pants, the Mexicans haul the lines from opposite ends of the boat. A plywood board lies across the center thwarts. When a squid is flopped onto the operating table, glistening like a newborn calf, Gilly threads the tag into its mantle, and a graduate student snips the plastic tie. Then they raise one end of the board, and the squid slides back into the sea. The entire operation, after a little practice, takes 30 seconds, tops.

Each squid, as it's captured, frantically tries to free its tentacles from the hooks by emitting great jets of water. Normally, the hydraulic force through its siphon tube would propel the animal quickly away. Held at the side of the boat, however, the squid is like an errant fire hose, soaking anyone in range. Gilly has a snorkeling mask over his glasses, but the water gets in anyway, and he flings the mask off.

The smaller ones are often in bad shape, some in tatters, because of attacks by other squid during their helpless ascent. The creatures are cannibalistic, terroristic, rushing on their prey with a forward thrust of the tail. Gilly has heard rumors about how dangerous Humboldts are—how the "red devils" have dragged down capsized fishermen. So far the one casualty of the evening is a bite on his finger. The squids' blood where the tag pricks them is blue, and the water in the bottom of the panga is black with their ink.

Surprisingly, the squid grow still once they are on the table. They lower a flap over black eyes the size of eight balls and show their distress only by the rapid blushing or blanching of their coloration. Humboldts can be maroon or ivory or any tone in between, according to the action of their chromatophores, or pigment cells. The color they display may depend on the depth of water; biologists don't really know.

A diver on the expedition has made a tape of two animals flashing under the surface. At first the pulses are out of phase, then they synchronize as the two squid come together. "What does this signaling mean?" Gilly asks. "I'm not the only one who believes they communicate."

Close to 90 Humboldts are tagged in the first night of work. But a couple of the squid, too ripped up to release, are held for analysis ashore. One, lying in the inky bilge, seems to have set its eyes on Gilly. The creature is dying, its color fading, its electricity ebbing. Air rasps through its siphon. Overtaken by what he later describes as a "profound sadness" that "must have been lying latent for 25 years," Gilly pulls out his knife, bends between the thwarts, and puts the squid out of its misery.

"Before then I never felt small—by that I mean diminished—in sacrificing such animals for scientific work," he recalls. "Maybe it was the size of the eye—it made it seem more living."