They are the ultimate wallflowers. By changing the colors of their skin, the cephalopods can slip into the background of almost any scene.
Squid are usually translucent or iridescent, but that doesn't mean they don't have a colorful trick or two up their eight sleeves.
Scientists in Japan were surprised to find a species of squid that was raised in captivity could change its coat depending on the state of its tank.
Usually, the white-squid is light in color to match the bright ocean surface where it is typically found. The cephalopods grew darker against a dirty layer of glass.
Researchers cleaned one half of the squid's tank while leaving the other half dirty after experimenting with the accidental discovery.
The video footage shows squid in action. As the species swims from the tank's algae side to the tank's clean side, its skin immediately changes from light to dark.
It is the first time a squid has been caught camouflaging under laboratory conditions.
This effect is striking. I am surprised that nobody has noticed this ability before, says Zdenek Lajbner, a Biologist from the Okinawa Institute of Science and Technology (OIST) in Japan.
It shows how little we know about animals.
squid camouflage has received less attention than other fish.
Most of the time, these creatures are in the open ocean, which means they don't need to change their skin to fit their environment. They shimmer or flicker in the sun.
Against a coral reef, these creatures might be more compelled to match the color of their background.
In the wild, the Caribbean reef squid has been caught changing its color to suit different types of coral.
The long fin inshore squid, which lives on the ocean shelf, is known to polarize its skin so that it cannot be seen by other people. The squid species can go from a lighter shade to a darker shade or vice versa. Changing color is not the same as that.
Onychoteuthis banksii, a deep-sea squid, can switch between transparency and pigmentation to camouflage in darker waters.
Ryuta Nakajima, who studies squid behavior at OIST, says that increases or decreases in squid populations are tied to the health of coral reef.
The adult white-squid studied in the current paper were raised in captivity after being collected from the wild, and all of them showed flawless color matching in the lab.
Within two seconds, the creatures could change their color. After every border-crossing event, this color change occurred, and the changes only ever occurred during the crossing.
Camouflage among squids is often thought to be based on transparency, but these squid are also using chromatophores to adjust their color to the background.
The authors of the study note that the same year they conducted these experiments, someone uploaded a video to YouTube that showed an oval squid, the same species of squid as the one in the paper.
White-squid have a rare combination of semitransparency and the ability to change body color via chromatophores which allows them to successfully live in both pelagic and reef environments.
It is an attractive model for studying the ecology, evolution, and neurobiology of versatile, dynamic camouflage.
The study was published in a journal.