The Jumbo Squid’s Astonishing Flashdance – Using Light For Communication and Camouflage
by Carolyn Sotka
These mounted cameras are a first for squid research and can help decode language and chatter of flashes and flickers. Photo by Joel Hollander
In a recent study published in the Journal of Experimental Biology out of Stanford University’s Hopkins Marine Lab, Ph.D. student Hannah Rosen and other scientists have been able to capture on film the complex communication dance of the Humboldt squid Dosidicus gigas. The jumbo squid, whose mantle length can measure up to 5 ft., were outfitted with a child-sized surf rash guard and fastened with National Geographic’s underwater critter cams (footage below).
Divers and the jumbo squid in the Sea of Cortez. Photo by Jim Knowlton and from GrindTV.
The Humboldt squid live in depths of 660 to 2,300 ft. in the Gulf of California and the waters of the Humboldt Current. They are known as the ‘red devil’ to fishermen because of their aggressive behavior and red and white undulating color changes, which can change pattern, amplitude and frequency to send different messages. The big question is trying to decipher what they are communicating – from broadcasting to prospective mates, or throwing down with potential rivals to hiding in plain sight and avoiding bigger predators.
Two types of ‘chromogenic’ behavior were documented without artificial lighting at depths of up to about 200 ft. One dynamic pattern, termed ‘flashing’ is characterized by a global oscillation (2–4 Hz) of body color between white and red. Flashing was almost always observed when other squid were visible in the video frame, and this behavior likely represents intraspecific signaling.
Another dynamic display termed ‘flickering’ was observed whenever flashing was not occurring. This behavior is characterized by irregular wave-like activity in neighboring patches of chromatophores, and the resulting patterns mimic reflections of light in the water column, suggesting that this behavior may provide camouflage for the squid.
The flickering is under inhibitory neural control. Although flashing and flickering have not been described in other squid, similarities are evident with other species.
Regardless of not exactly knowing what the squid are saying, the footage makes for a good show and may help shed light into observing other deeper sea critters, often elusive in the dark fathoms of the sea.
Check out National Geographic’s coverage for additional footage and links. — CS