Various life forms use camouflage to hide themselves from predators. Many predators have eyesight that extend beyond the human visible spectrum colors (ultraviolet ). So does the comouflage colors extend to the ultraviolet range too ?
For example : when a chameleon camouflages itself against a leafy branch, does it colors match the leaf colors too when looked in the ultraviolet region of the spectrum ?
What about green parrots and their ultraviolet color compared to green vegetation ?
Neither chameleons nor parrots are particularly camouflaged.
This article says “The lizards’ skin also contains yellow pigments, and blue mixed with yellow makes green, a “cryptic” color that camouflages them among trees and plants, Milinkovitch said.”
This article says “Parrots, and many other animals, use pattern and color variation as a means of camouflage. The purpose for bold patterns and vivid colors is to disrupt the outline of an animal’s body.”
Anyways, let’s not get into a debate in what counts as camouflage and what does’nt. I am really interested in knowing that when an animal blends into the surroundings, does it do so for its own color spectrum perception or it’s predators ?
What an interesting question. I don’t know the answer, but would assume the answer is yes for anything under enough predation pressure from critters able to perceive UV. Found this pretty technical article which seems to indicate some do, but that the selective pressure for visual sexual markers can complicate matters.
There is nothing “special” about the UV or IR range, it is simply the region of the EM spectrum immediately outside human perception. Therefore, AFAIK nature doesn’t put a hard edge at that region of the spectrum for humans’ benefit or detriment.
Tamerlane: found a decent reference, sure, under selective pressure, camouflage works outside of an animals visual range. Kinda a bonus for the species, it can still rely on visual cues for inter species communication.
Insects that see into the UV tend to not see very deeply in the red, as I recall, ants and honeybees don’t see red very well, and red lights can be used to study them, which humans see well. That’s kinda the thing – animals see outside human range in some ways, and then fail to conform to human vision in other ways.
What predators are these? As a mammal I’m biased towards our kind, and UV vision is pretty rare.
Among mammals UV vision largely unknown - among insects, arthropods, fish, lizards, and birds a lot of species see into the UV.
It’s been found that in some bird species where the male and female look identical to us their feather colors differ by gender in the UV. Which those birds can see. Nearly 70% of parrots, for example, have UV colors in their plumage we can’t see, and even those that don’t can see into the UV.
Rodents see somewhat into UV - it helps them see urine.
Even if humans had the photoreceptors to see into UV, we would still not see very far as UV light doesn’t even reach our retina because the lens filters it out. People who have cataracts and get an artificial lens can sometimes see a little farther into the UV range.
Why do rodents need to see urine?
This is almost but not quite right. When artificial lenses were first introduced, anyone getting them could see a short ways into the UV because the pigment in the blue receptors responds to those wavelengths. But they found that exposing the retina to UV could damage it, so they changed the lenses to be opaque to UV.
To follow conspecific trails/hiding places etc.
Okay, then without your lens you would see a bit into UV. But then in the long term your eye is more susceptible to UV damage, so it’s a positive adaptation. Other species may not live long enough for UV to be a detriment.
I don’t know of many predators with UV vision that UV camouflage would help protect against. One of the few is the Mantis Shrimp. Much has been said about the “amazing” vision of the Mantis Shrimp. The capabilities of mantis shrimp ARE amazing, but you should be aware that no one species has all the capabilities spoken about as part of Mantis Shrimp vision – it’s a case of a lot of them each having one or more facets. But it has indeed been suggested that their UV vision is used, in part, to locate prey ( Mantis shrimp - Wikipedia , especially note 24) That being the case, it wouldn’t surprise me if their potential prey tried to blend in in the ultraviolet as well as in the visible (clean water provides excellent UV transmission, by the way.)
Most UV vision I know of, though, is by things like bees, who use it to locate pollen and nectar – flowers do the opposite of UV camouflage, making themselves VERY visible in the UV, standing out like neon signs against the humdrum non-UV would of chlorophyll.
Birds live a long time, some of them having the same lifespans as human beings, yet they seem to do OK with UV vision. So I’m not sure that your conclusion is valid. It still leads to the question of how birds avoid long-term UV damage to their retinas.
Apparently some camouflage using UV yes, but not to leaves…
Aegean wall lizards (Podarcis erhardii) in Greece in the wild choose to sit on rocks that best match their back coloration as viewed and perceived by an avian predator from above (matching coloration as seen inclusive of the UV spectrum).
Not so sure how common it would be though. You need a predator with UV perception (mostly birds, few lizards with uv perception of significance) and prey camouflaging in high UV and UV reflectance environments during the day. Fairly little UV gets through in dappled or shady (leafy) areas or underwater, so not much pressure to match UV patterns there. Not too many lizards see well in the UV portion of the spectrum. (Hence this big deal over the desert iguana having UV perception used see scent markers at a distance they could not smell them and possibly to better see plants of interest.)