Squid continuously adjust their colouration to signal fellow squid or for camouflage, according to a rare study conducted in the animal's natural environment.

Credit: Joel Hollander

Hannah Rosen of Stanford University, California, and her colleagues fitted three Humboldt squid (Dosidicus gigas) in the Gulf of California with cameras (pictured) that recorded their underwater activity. The authors identified two distinct patterns of colour changing. Whole-body 'flashing' between white and red was seen in the presence of other squid. 'Flickering' involved wave-like patterns that seemed to mimic the reflections of sunlight in the water, and occurred whenever there was natural light and the animal was not flashing.

The team suggests the flashing behaviour is a form of intra-species signalling, while the flickering represents dynamic camouflage.

J. Exp. Biol. 218, 265–275 (2015)