Octopuses Can See Through Their Skin and Camouflage Accordingly

Octopuses Can See Through Their Skin and Camouflage Accordingly

Cephalopods, which include octopuses, squid, and cuttlefish, are capable of the most incredible feats of camouflage. They can change the color, pattern, and texture of their skins on the fly to blend into the background, confuse their prey, or communicate with one another.

The octopus's clever camouflaging ability has been known for years. They can change the pigment in their skin almost instantly to reflect their surroundings. Two studies published in the Journal of Experimental Biology in 2015 suggest that the octopus can sense light in its skin. When the octopus' arms detect light, the eight-armed creature pulls them close to its body.

Researchers at the University of California, Santa Barbara, discovered that the California two-spot octopus could sense light directly through its skin without its central nervous system. This is due to the discovery by the UCSB team of a family of proteins known as opsins in the octopus' skin.

Opsins are light-sensitive receptor proteins found in the retina's photoreceptor cells.

The study looks at how cell structures known as chromatophores interact with light and is a follow-up to octopus research from the 1960s.

How Does an Octopus Change Its Colour and Texture?

These opsin molecules were discovered in cell nerve endings. Hair-like extensions detect light and send a chemical signal to chromatophores, which are specialized color-changing cells on their skin. Opsins are found in the chromatophores of some squid and cuttlefish, which is why scientists believe cephalopods have such an uncanny ability to blend in. Each chromatophore has a pigment sac surrounded by muscles that can change color by stretching or squeezing the sac. These camouflage masters have up to 96,000 chromatophores per square inch of skin.

Some cephalopods can change the texture of their skin as well as their color. According to a study published in the Journal of Morphology, cephalopods have small muscles on their skin that either poke up vertically into a spike or smooth their skin. As a result, they can morph into weird patterns and change textures in their environment, allowing them to imitate corals, rocks, or sand.

It is well known that the octopus' eyes are used to control the chromatophores in its skin, but tests on patches of octopus skin with different colored lights have led to the belief that the skin itself can "see" and adapt to its surroundings. To be clear, it's not the same as seeing with your eyes, but it's still a way to sense your surroundings. In some ways, it's like having a sixth sense.

To put this phenomenon to the test in 2015, Desmond Ramirez, a doctoral student in the Department of Ecology, Evolution, and Marine Biology, and Todd Oakley, the study co-author and EEMB professor of the University of California, Santa Barbara, took patches of skin from 11 hatchling and individual bimac octopuses (Octopus bimaculoides), mounted them on Petri dishes with insect pins, and used light-emitting diodes to shine different wavelengths of light onto the skin preparations. When exposed to continuous bright white light, the chromatophores expanded quickly and remained expanded, pulsating rhythmically. Red light, on the other hand, caused slow, rhythmic muscle contractions but not chromatophore expansion.

The chromatophores were most responsive to wavelengths of 480 nanometers (nm, or billionths of a meter) in these experiments, corresponding to blue light. This is also the wavelength at which some opsins absorb the most light. As a result, Ramirez and Oakley predicted that opsins are present in octopus skin, acting as light sensors.

This process, which suggests that the skin's light sensors are linked to the chromatophores, has been dubbed Light-Activated Chromatophore Expansion, or LACE.

"Octopus skin does not sense light in the same detail that the animal does when it uses its eyes and brain," study lead author Desmond Ramirez explained. "But it can sense an increase or change in light. Its skin is not detecting contrast and edge but rather brightness."

It's still unclear whether octopus chromatophores act as light sensors, mechanical receptors, or both, but Ramirez and Oakley intend to find out in a series of new experiments aimed at determining what kinds of behaviors they're involved in.

1 Response to "Octopuses Can See Through Their Skin and Camouflage Accordingly"

  1. One gotta love their uncanny ability to surprise us with a new and weirder characteristic.