Humboldt squid

Humboldt squid flash different colors as a means of communication; video screen grab

Humboldt squid are intelligent, complex creatures that communicate by rapidly changing colors, or flashing.

It's a remarkable and intriguing phenomenon that has been witnessed by scientists and intrepid recreational divers, who have ventured into the realm of these voracious and at times very aggressive cephalopods.

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But now scientists are on a mission to figure out what Humboldt squid, also called jumbo squid, might be saying to each other, what messages they might be conveying with vivid flashes—from white to deep red—that are sometimes fast, and other times slow.

Humboldt squid

Squid is fitted with a Crittercam; photo by Joel Hollander

Their first step toward solving this mystery was to capture footage using "Crittercams" supplied by National Geographic.

The study was conducted by researchers at Stanford University's Hopkins Marine Station in Pacific Grove, California. The results were published last week in the Journal of Experimental Biology.

The cameras, attached to free-swimming Humboldt squid in Mexico's Sea of Cortez, captured black-and-white footage (posted above) showing not only flashing behavior, but interactions that could be attempts at mating.

(The footage is black-and-white because the camera was designed for low-light conditions, allowing researchers to obtain higher resolution at lower depths. Since the squid flash only from white to red, all that was needed to detect flashing was contrast.)

Humboldt squid

Recreational divers observing the squid in the Sea of Cortez; photo by Jim Knowlton

Flashing occurs when the squid contract or expand pigmented cells called chromatophores. It can be seen at several points in the footage, which is the first involving Humboldt squid wearing cameras.

"A view into this previously secret world was like a dream come true," said Hannah Rosen, a doctoral student who led the study.

Rosen, in a written paper, stated that the flashing—when the animals rapidly changed color throughout the length of their bodies—was always associated with visual contact with other squid.

"The frequency and phase relationships [synchronization] between squid during flashing can be changed, and this suggests that there is some information being conveyed that makes minute control over these details important to squid," Rosen wrote.

Another behavior observed was more of a flickering, which was perceived to represent a means of camouflage, versus communication. This behavior occurred closer to the surface.

Only three squid were fitted with cameras, but researchers plan to do more in-depth study of this particular species of squid, whose range is from Chile in South America as far north to Alaska.

Humboldt squid

Humboldt squid shown interacting via Crittercam; video screen grab

Humboldt squid (Dosidicus gigas) are worth keeping an eye on. Their range expansion up the West Coast of North America is a fairly recent phenomenon, and it remains unclear what impact they’re having on fisheries.

These squid, which can measure to about 6 feet, are far more voracious than the legendary and much larger giant squid. Humboldt squid, whose arms boast suckers lined with razor-sharp teeth, are both opportunistic and cannibalistic.

They’ve been known to attack divers and steal away with camera equipment.

Where there is one, there are usually hundreds, or possibly thousands, so the more scientists know about them, the better.

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