According to recently published research, many species of octopus can detect and respond to light, even when they cannot see it with their eyes.
Dr Nir Nesher – a lecturer in marine sciences at the Ruppin Academy (Israel) – said the octopuses had no bones and joints. Each point of their tentacles can flexibly move in all directions, which Nir Nesher calls “endless freedom”.
According to the New York Times, the team recently discovered that octopuses are able to avoid light using only these tentacles. Dr Itamar Katz – one of the study’s authors – said that in many of the team’s experiments, as long as a beam of light hits one of the octopus’s eight tentacles, that limb will pull away. immediately from the light.
This mechanism occurs even when the octopus is sleeping, that is, it detects light without eyes. The results were published in the Journal of Experimental Biology.
The team did a number of experiments, in which they put the octopus in a small box, leaving only a hole in the top for a tentacle to enter. The job of this tentacle is to sample the food that is illuminated.
The team found that when the tentacles hit the light, they immediately dodged in less than a second and waited for another opportunity to approach the food. When the light stops working, the octopus immediately takes the loot.
According to Dr. Nesher, this is an unexpected ability. “Octopuses seem to be able to see the light with their tentacles. They really don’t need eyes to do that, ”said Nesher.
The speed at which the tentacles react to light is not the same. The team believe that when the octopus lives in the dark for a week or a month, the reflexes will be faster.
According to the team, this ability to sense and adapt to light can consume a lot of energy, as it is an important behavior for their lives.
Dr Tal Shomrat explains that this reflex ability is how the octopus protects its limbs from certain species such as crabs and fish. Because when they see the tentacles moving with the light, these species can take it as a simple sea worm.
However, the mechanism by which the tentacles sense and respond to light remains unclear. According to the team, there are documents showing that there are light-sensitive receptors in the limbs of octopuses, but there is no evidence that they are linked to this reflex.
The team added that in anatomical experiments, the octopus’ tentacles were no longer able to avoid light when separated from the body.
Additionally, when the tentacles are scratched, the octopus’ light avoidance reflex persists. But if that part of the skin is deeply damaged affecting some of the underlying muscles, they lose their ability to respond.
