Why it's so hard to find giant squid.

Previously published Slate articles made new.
Dec. 22 2006 3:30 PM

Giant Squid, Where Are You?

If they're so big, why can't we find them?

On Friday, a group of Japanese scientists unveiled a video of a live giant squid—what they claim are "the first ever moving pictures of a giant squid." (You can watch the video here.) In a 2005 Explainer column, reproduced below, Daniel Engber wrote that giant squid are elusive because they live in a dark, deep-sea environment. "Cameras can see only what's within range of an artificial light, and light can scare off some dark-adapted critters," he wrote. (Also see Grady Hendrix's explanation for why we should leave giant squid alone.)

This week, a British journal published the first-ever pictures of a giant squid alive in its natural habitat. A pair of Japanese researchers set up an apparatus that photographed the creature as it wrapped its tentacles around some bait attached to a deep-sea camera. How did the giant squid remain elusive for so long?

Daniel Engber Daniel Engber

Daniel Engber is a columnist for Slate

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The difficulty of underwater exploration. The giant squid may be no harder to find than any other animal that lives at the bottom of the ocean. Submersibles that travel thousands of feet underwater have provided scientists with only a limited view of deep-sea life. Cameras can see only what's within range of an artificial light, and light can scare off some dark-adapted critters. Plenty of deep-sea animals other than giant squid have shown up in fishing nets without having been captured on film in their natural environment.

The giant squid seems especially mysterious for a couple of reasons. First of all, its incredible size—giant squids can be 40 feet long or more—makes it hard to believe that it can't be seen alive. Second, dead giant squids surface with surprising regularity. In the last few years, there's been a dramatic increase in the number of giant squid carcasses that have been discovered. So, why is it so hard to find a living giant squid when the dead ones are a dime a dozen?

For one, we don't really know where and how giant squid live. Specimens have been found all over the world, but it's not clear if they have regular migration patterns. We know sperm whales eat giant squid—remains have been found in the whales' stomachs—so some researchers have tracked the predators to find the prey. The Japanese researchers looked for the giant squid where sperm whales were known to congregate. Their camera-on-a-rope technique wasn't particularly innovative. (More adventuresome researchers have attached cameras to the sperm whales, for example.) Giant squid experts think they just got lucky.

Bonus Explainer: What's with all the giant squid carcasses? Dead giant squids may be more buoyant than the carcasses of other deep-sea creatures because they have an unusually high concentration of ammonium ions. Since the ammonium is lighter than seawater, the carcasses tend to float, making them easy to spot. (Giant squids use the ammonium to keep from sinking while they're alive, too.) It's less clear why so many have turned up in the last few years. One theory suggests that an increase in deep-sea fishing—of orange roughy in particular—has disturbed the giant-squid habitat. Others say that the squid deaths have been caused by underwater seismic surveys using air guns. Or it could be global warming.

Bonus Bonus Explainer: What's the difference between squid and giant squid? The giant squid isn't just a big ol' version of a regular squid—it has its own genus, called Architeuthis. (There may be several species of giant squid, but no one knows for sure.) The lesser-known "colossal squid," of the genus Mesonychoteuthis, may be even bigger and nastier than the giant squid. It has a larger beak than the giant squid and has hooks on its tentacles. While a few specimens of colossal squids have been discovered, no one has yet seen one in its natural habitat.