OKINAWA, Japan — Researchers in Japan have learned that squids camouflage using chromatophores similar to their fellow cephalopod family members, octopus and cuttlefish.
Based on a new study, scientists in Okinawa, Japan, observed oval squid (Sepioteuthis lessoniana) adapt the coloration of their skin using their chromatophores according to the background substrate. Until now, squids' ability to camouflage has long been thought to be based on transparency.
Over the years, research has mostly been conducted on cuttlefish and octopus due to their ability to background match and mimicry along the seafloor and coral reefs. Squid live in the open ocean and are not faced with the same predators and their defense strategies change, researchers say, therefore they're less likely to be seen adapting to backgrounds.
A group of scientists from the Okinawa Institute of Science and Technology Graduate University performed a controlled experiment to see how squid in captivity camouflaged to the substrate. Dr. Ryuta Nakajima, an OIST visiting researcher, said they wanted to see how squid would react when closer to a coral reef or if chased by a predator near the ocean floor.
Additionally, the investigation was prompted when researchers were cleaning the tank one time and noticed that the animal would change colors depending on which side of the tank it was on — the cleaned or the algae.
During the experiment, scientists put an underwater camera inside the water and placed a regular camera above. There, they watched the squid move between the clean and algae-filled side of the tank.
And the results were very telling. When squids were on the clean side of the tank, they were transparent and light in color and when they moved to the algae-filled side, they quickly became darker in color.
The research uncovered an ability that had never been recorded in a controlled experiment. Scientists learned that squid will camouflage to match a substrate in order to survive.
"If substrate is important for squid to avoid predation then that indicates that increases or decreases in squid populations are even more tied to the health of coral reef than we thought," Nakajima said.
Researchers are hopeful this new discovery will lead to more findings about the species and cephalopods in general.
