Some squid and octopuses can switch between two different types of camouflage according to which predators are nearby, scientists have found.
In the cold, dim environment between 600 and 1,000 metres deep — known as the mesopelagic zone — some creatures have evolved to be transparent to avoid being seen from below against ambient light. However, some predator fish get around this using light-emitting organs called photophores that function as biological searchlights, scattering blue light from the eyes and internal organs of their prey.
For this reason, many animals in the lower depths are naturally red or black to reflect as little light as possible at blue wavelengths. But this means their silhouettes are easy to see from below.
Japetella heathi, a bulbous, short-armed octopus, and Onychoteuthis banksii, a squid, have the best of both worlds in that they can switch rapidly between the two states.