Since cephalopods can detect the polarization of light, it may not be surprising that they also have control over the polarization of the light that cuts them out. Some researchers speculate that they are privately communicating privately by polarization as many of their predators can not detect polarization.


Also, remarkable is that some cephalopods can take over the behavior of other animals and inspect them by adjusting their attitude to it. The imitation of other animals is more common in nature, but the mimic octopus is king because it has already been observed in countless disguises. Is it a flatfish? A sea hose? a lionfish? a crab? seaweed? an eel? a starfish or anemone? Nope, it's the mimic octopus. He changes costume depending on which predator he wants to deter or what prey he wants to attract.


How does the entire camouflage system work right now? Well, that's an active area of research and quite complex but incredibly interesting!

Spoiler Alert, click show to read: 
The chromatophores are a sac containing hundreds of thousands of pigment granules and a large membrane that is folded when retracted. There are hundreds of muscles radiating from the chromatophore. These are under neural control and when they expand, they reveal the hue of the pigment contained in the sac. Cuttlefish have three types of chromatophore: yellow/orange (the uppermost layer), red, and brown/black (the deepest layer). The cuttlefish can control the contraction and relaxation of the muscles around individual chromatophores, thereby opening or closing the elastic sacs and allowing different levels of pigment to be exposed. Furthermore, the chromatophores contain luminescent protein nanostructures; there are tethered pigment granules which modify light through absorbance, reflection, and fluorescence between 650 and 720 nm.

In cuttlefish, activation of a chromatophore can expand its surface area by 500%. There may be up to 200 chromatophores per mm2 of skin. In Loligo plei, an expanded chromatophore may be up to 1.5 mm in diameter, but when retracted, it can measure as little as 0.1mm.

Retracting the chromatophores reveals the iridophores and leucophores beneath them, thereby allowing cuttlefish to use another modality of visual signalling brought about by structural coloration.

Iridophores are structures that produce iridescent colors with a metallic sheen. They reflect light using plates of crystalline chemochromes made from guanine. When illuminated, they reflect iridescent colors because of the diffraction of light within the stacked plates. Orientation of the schemochrome determines the nature of the color observed. By using biochromes as colored filters, iridophores create an optical effect known as Tyndall or Rayleigh scattering, producing bright blue or blue-green colors.

https://www.nature.com/scitable/topi...-the-144048968



The octopus has 3 hearts to ensure that enough of its oxygen rich blue-colored blood has reached 9 brains. His system heart pumps blood through his entire body, his 2 branched hearts are pumping blood through his gills to increase his oxygen uptake. Oxygen transport is regulated in octopus blood by the copper-rich hemocyanin protein. This protein makes the blood very viscous (poisonous), which makes it more difficult to pump but in low-oxygen cold conditions, haemocyanin is more efficient than the iron-rich hemoglobin protein we use. Remarkably, haemocyanin is dissolved in plasma instead of being worn by red blood cells as well as blood staining blue instead of red.


(Also, crab cranes use hemocyanin for their oxygen transport.)​

The octopus's heart rate remains quite constant, even under exertion, but this he compensates for by increasing the pumped volume per heart rate. In addition, in his gills, he has receptors that allow him to adjust the amount of oxygen that he absorbs from the surrounding water, allowing him to keep his uptake even.

Breathing itself occurs by dragging water into the mantle and passing through the gills. The oxygen-poor, carbon-rich water is injected back into the environment via the sifo. However, at rest, more than 40% of the oxygen required is absorbed through the skin. This drops to 30% when he swims because more water flows through the gills.