This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
Editor's Note: William Gilly, a professor of cell and developmental biology and marine and organismal biology at Stanford University, is traveling with a group of students on board the Don José in the Sea of Cortez. They will monitor and track Humboldt squid and sperm whales in their watery habitats. This is the group's eighth blog post.
Gilly's Note: Although we have been focusing on intertidal organisms for the last several days, we cannot forget the squid. During afternoon lulls between early-morning low tides, two students have been addressing the question of how Humboldt squid of such vastly different sizes—from junior 20-centimeter to jumbo 75-centimeter specimens—can all be sexually mature, ready to spawn. Emilie and Molly have been analyzing the stomach contents of both large and small squid that we caught last week, the stomachs now in plastic bags in the freezer. After peering at masticated morsels through a microscope for several days, thoughts of feeding take on a new depth. Sometimes considering a simple question leads to unexpectedly broad insights.
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SEA OF CORTEZ—
The seagulls
Our crew member, Felix, stands in the panga, silhouetted against sky and sea. A bucket of scraps from this evening's catch of triggerfish sits beside him. Behind the boat, the island of Santa Catalina rises abruptly from the Sea of Cortez. The sun is setting and the light is soft and stirred in reds and yellows. The seagulls sit on the ocean's surface and bob with the waves. There is a large flock gathered for the sunset and all is peaceful, the day dwindling into night. Then Felix starts to toss the fish scraps into the water.
There arises a flurry of wings and squawks. The gulls converge and swoop at the water, plunging their beaks at the fish.
A victor emerges from the scuffle, a morsel in its beak. The gull beats its wings rapidly, accelerating away from the others as they scrap in confusion. Two other gulls pursue and snap at the fish part that hangs precariously from the victor's beak as it dodges and curves in flight, trying to keep hold of its prize.
The feeding frenzy continues. Once I see a gull's meal robbed, snatched straight from its beak. But more often a gull will choke the scraps down mid-flight. With each jerk of its wings it pulls the fish further into its gut, choking it back in hurried gulps with its pursuers pressed on its tail.
The squid
The boat's light illuminates the water, and the small but mature Humbolt squid dart under its glow. From the deck, squid guts are thrown into the water. Almost instantly, hungry tentacles snatch them up. The squid darts away, its meal wrapped in its tentacles, its beak snipping at the entrails. But it moves only a short distance before another squid's arms flicker outwards and steal the food with a quick, decisive propulsion and snatch. This squid, in turn, can only get so far before another wrestles the guts from its arms.
The squid flash aggressively with the frenzy of feeding. They play tag with the guts of their own kind. The meal switches arms so fast I can barely keep track. Gilly tells me that loligo squid, studied in Monterey, steal food as soon as they begin to hunt, as soon as they are born. Humboldt squid appear no different.
The humans
I awake from my nap, rub my eyes, roll over and cast my gaze out the window. The window frames the ocean, the sun and the distant ridges of land. In my blurry-eyed stupor I mistake it for a postcard.
Ah, to be top predator!
On this ship, the bell rings three times a day to announce mealtimes. I wait for the bell to ring.
There will be no desperate scrap. The meal is a certainty; there is ample food for everybody, a portion for all. The meal is such a certainty that mealtimes structure our day: 8 A.M., 1 P.M., 8 P.M. Our body clocks tick by these times. At the dinner table, we chew pensively on tacos tailored to our mouths. We pause to make leisurely conversation; we stir guacamole with our forks. We let flavor melt into our mouths, and we savor texture against our tongues.
If tacos do not please us, we can push them to one side. We can afford to.
For the gulls, for the squid, there is no time to savor, no time to pause. There can be only the single-minded focus on drawing food into the stomach—the difference between life and death.
Image of gulls in air courtesy of Susan Shillinglaw; image of gulls over fish scraps courtesy of Chris Rurik; image of students feeding on the Don José courtesy of Rhanor Gillette.