William Gilly ’72

William Gilly ’72 at Stanford’s Hopkins Marine Station in Pacific Grove, Calif., holding a Humboldt squid.
William Gilly ’72 at Stanford’s Hopkins Marine Station in Pacific Grove, Calif., holding a Humboldt squid.

Most people know squid as golden, fried rings of calamari, but for William Gilly ’72, these tentacled mollusks have been subjects of scientific study for four decades. He has investigated how squid live, dive, and communicate, and what they could tell us about changing ocean conditions. 

A professor of biology at Stanford University, Gilly focused early in his career on electrophysiology, the electrical properties of cells and tissues. He conducted laboratory studies on market squid, a small species that, like all squid, has giant nerve cells.

But since 2000, Gilly has been pursuing a larger, more enigmatic subject: the Humboldt squid. These hefty beasts can grow to 6 feet and 100 pounds. Known as diablos rojos — red devils, in Spanish — Humboldt squid are voracious predators and serve as prey for other animals such as elephant seals and sperm whales, forming a key link in the marine food web. 

“Squid are really important because there are so many of them; they make so many babies,” Gilly says. “And those babies are food for everything in the ocean.” Fisheries also catch more tons of Humboldt squid each year than any other invertebrate species in the world. 

Gilly’s work ­frequently takes him to Mexico’s Baja California, the site of a robust Humboldt squid fishery that dramatically declined after a 2009 El Niño oceanographic event altered the animals’ biology. Large Humboldt squid suddenly disappeared in the Gulf of California, leaving behind small ­progeny only 1 foot long but already sexually mature. Gilly thinks the El Niño’s warm oceanographic ­currents caused the large squid to give birth to stunted, precocious offspring that resemble the smaller form of the species usually found in tropical waters. 

Gilly and colleagues have hauled Humboldt squid onto boats in the Gulf of California to attach data-logging tags. These instruments recorded squid diving as deep as a mile, and also swimming around in a mid-ocean zone with very little oxygen. “That was a real surprise, because these are supposedly big, active, athletic animals that are very sensitive to low oxygen,” Gilly says. He has learned that Humboldt squid drastically slow their metabolism to dive and feed in such an inhospitable setting. 

As warming oceans cause these low-oxygen zones to expand, the Humboldt squid’s range also grows. The appearance of Humboldt squid in new areas can alert scientists to otherwise invisible changes in the ocean. “It’s possible that squid are like an advance warning sign of climate change,” Gilly says.

In one project, Gilly has strapped video cameras to Humboldt squid and filmed the mysterious signals they emit, which look like flickering, color-changing lights. Another project is exploring whether discarded squid guts, rich in omega-3 fatty acids, could be used to supplement farmed-fish feed. 

Gilly is happy if his work can benefit society, fisheries, or the environment, but pure discovery remains his true motivation. “It’s never been the driving force for me to produce some beneficial thing,” he says. “It’s much more basic exploration.”