Eyes not required: The octopus can "see" light with its skin, scientists discover
Look Ma! No eyes!Octopuses (or octopi, for you latin geeks) are amazing creatures. If you've never seen their color and shape-shifting abilities, which are used for both camouflage and communication, make sure to check out the videos below. But as if that wasn't cool enough on its own, new research has found that our tentacled friends are even more fascinating than we previously believed. A new paper published in the Journal of Experimental Biology reveals that octopus skin has some of the same pigment proteins found in eyes, making it responsive to light.
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It's all part of the chameleon-like mechanism that allows octopus skin to change color:
These clever cephalopods can change colour thanks to specialised cells called chromatophores, which are packed in their thousands just beneath the skin surface. Each of these cells contains an elastic sac of pigmented granules surrounded by a ring of muscle, which relax or contract when commanded by nerves extending directly from the brain, making the colour inside more or less visible.
Octopuses are thought to rely mainly on vision to bring about these colour changes. Despite apparently being colour blind, they use their eyes to detect the colour of their surroundings, then relax or contract their chromatophores appropriately, which assume one of three basic pattern templates to camouflage them, all within a fraction of a second. Experiments performed in the 1960s showed that chromatophores respond to light, suggesting that they can be controlled without input from the brain, but nobody had followed this up until now. (source)
It is known that the octopus' eyes are used to control the chromatophores in its skin, but thanks to tests done on patches of octopus skin with light of various colors, it is now believe that the skin itself can "see" and adapt to its surroundings. To be clear, it's not the same kind of seeing as with eyes, but it still is a way to sense the surrounding environment. A kind of sixth sense, in a way. And maybe it's the skin that is helping match colors with whatever is around for better camouflage, since the eyes are color blind.
If you want to see more cool stuff that octopuses can do, check out this marine Houdini:
And the amazing master of disguise, the mimic octopus (make sure to click the link and watch the videos):
The mimic octopus lives exclusively in nutrient-rich estuarine bays of Indonesia and Malaysia full of potential prey. It uses a jet of water through its funnel to glide over the sand while searching for prey, typically small fish, crabs, and worms. It also is prey to other species. Like other octopuses, the mimic octopus' soft body is made of nutritious muscle, without spine or armor, and not obviously poisonous, making it desirable prey for large, deep water carnivores, such as barracuda and small sharks. Often unable to escape such predators, its mimicry of different poisonous creatures serves as its best defense. Mimicry also allows it to prey upon animals that would ordinarily flee an octopus; it can imitate a crab as an apparent mate, only to devour its deceived suitor.
This octopus mimics venomous sole, lion fish, sea snakes, sea anemones, and jellyfish. For example, the mimic is able to imitate a sole by pulling its arms in, flattening to a leaf-like shape, and increasing speed using a jet-like propulsion that resembles a sole. When spreading its legs and lingering on the ocean bottom, its arms trail behind to simulate the lion fish's fins. By raising all of its arms above its head with each arm bent in a curved, zig-zag shape to resemble the lethal tentacles of a fish-eating sea anemone, it deters many fish. It imitates a large jellyfish by swimming to the surface and then slowly sinking with its arms spread evenly around its body. (source)