is this octopus-camoflage video real?

[Graeme]

Yeah, red light is absent after I think a few hundred feet (but don;t hold me to the actual depth, I can't remember). A fair whack of deep sea animals are in fact red, becuase red light doesn't show up down there. I think a few predators hunt using red light generated below the eyes as this makes them invisible to prey... or something.

Graeme

 

[Neogonodactylus]

In clear ocean waters, long wave lengths drop out most quickly and generally are depleated by 20 m. The amount and color of particulate material in the water will have a considerable impact on this. In shallow waters with broad spectrum lighting, red is certainly an effective color over the few meters that these animals are visually interacting with other animals having color vision. In dim illumination, at moderate depth, or in murky waters, red more or less equates to dark.

Roy

 

[monty]

In addition to the iridophores, there are also the more boring leucophores, which are just masses of white stuff, more or less, that provide sort of a background, diffuse reflection of the color that's around.

Although red light certainly drops off rapidly, there is still a significant amount of it at the depths that a lot of octopus and cuttlefish live-- certainly it's a factor in tidepools and reefs down to 50 feet or so, although even there it's attenuated. I always like to bring a small flashlight when diving, even during the day, because even at shallow depths, shining a white light can often reveal things that are very hard (for human eyes) to see in the natural light-- of course, that's probably both from the camouflage being optimized for the natural light levels and because human eyes are optimized for the spectrum of sunlight outside the water (which the flashlight tries to emulate).