I could paint two regions in a way that makes them appear to be the same color from the point of view of an organism that sees only black and white, but not from the point of view of some organisms that see colors. Are there examples in nature of camoflauging that fools certain visual systems and not others? (I’m surprised if there are not, but I am interested in seeing examples.)
A recent article in New Scientist is on deep water fish that use species distinctive red fluorescent colouration that other fish can only see at close range. The theory is that the fish use this to identify other fish of the same species (for the obvious reasons), without showing up too much.
Scorpionfish appear to use the same mechanism to camouflage themselves against the reefs, which have a similar red fluorescence.
Not quite what you were looking for, but an interesting use of colour and visibility in the animal kingdom.
Si
I have seen that some flowers have a different appearance under ultraviolet and that some bees recognize this. This was back when Discovery still had teaching-type shows on it.
This is true, but I think it’s more of an advertisement for pollinators than about camouflage for flowers. It is still interesting.
Bjørn Rørslett has a pretty good resource about this. The first link has an example right away, and the second linked page has a list of flowers and UV photos of them.
Not exactly natural, but human hunters sometimes wear blaze orange in a camouflage pattern, such that they’re not easily visible to the colorblind deer, but are easily visible to the other hunters with guns.
This may not be in nature but my wife’s grandfather was used as a spotter in recon planes during WWII. His advantage was color blindness - because he couldn’t see certain colors, he had an easier time spotting camouflaged enemy positions. The camouflage failed to break up outlines.
In terms of nature, some species of snakes are able to see heat. This will defeat every type of camouflage out there. There are snakes that hunt bats in complete darkness using nothing but heat signatures.
Tigers and zebras, according to the wikipedia article on camouflage:
Birds can see into the ultraviolet, whereas most mammals can’t. Therefore insects and other organisms that reflect UV will be more visible to birds than they are to mammals.
This paper found that species of butterflies and moth that reflected UV were more vulnerable to predators that foraged during the day (mainly birds), but were no more vulnerable at night when most predators are not UV sensitive (mostly mammals).
The plumage of many species of birds is reflective in UV, including some that are drab in visible light. That means they are much less visible to mammals than they are to other birds. (However, since the most important predators on birds are often other birds, this may not offer that much protection from predation.)
Not exactly camouflage, but fascinating. I learn something new every day.
I have heard an alternative theory. This states that zebra stripes, for example, are not really intended to ‘blend in’ with the background. Their main advantage is that, when many zerba are gathered together, the stripes make it difficult to discern the outline of any individual, which makes life harder for the predator. In other words, the stripes enhance the concept of ‘safety in numbers’.
I am not saying this theory has any merit. It’s just an alternative that I heard or read somewhere.
Old thread, resurrecting because of the zebra camoflauge theory. Research shows a more likely reason for zebra stripes, the stripes confuse the compound eyes of flying insects. This has been shown in the lab with artificial black and white striped surfaces, and I think was confirmed by observation of real zebras and flying insects.
This seems like a much more reasonable explanation for the advantage zebra’s stripes provide. It has been easy enough to spot a heard of zebras from a distance where they typically graze so that we have lots of photographic evidence of that. I doubt they would tend to ‘hide out’ in tall grasses where the stripes might work as decent camoflauge because that tall grass gives cover to their predators. I think their typical predator’s vision is quite good enough to pick out the individual animals up close.
I don’t think the camouflage nature of zebra patterning was posited to be blending in with the environment as much as it was disruptive to perception. It can be difficult to pick out an individual zebra from a herd, or determine which way it is facing (which is a key piece of information if you intend to chase it) - here’s an example: https://gcdnb.pbrd.co/images/5HZXDwuKZpFA.png?o=1
I don’t think the recent stuff about flying insects necessarily negates the value of the stripes as disruptive camouflage - nature doesn’t necessarily invent things with singular purposes.
Is there any evidence confirming the disruptive camouflage concept? That picture is nice but doesn’t look like it will stop a lion from getting close enough to kill either one of those zebras. I’m not saying it has no such function at all either, not negated, but one may be far more useful to the survival of zebras than the other.
There’s evidence that disruptive patterning works. Not sure how you would ethically test if it works for lions vs zebras
Observation could help confirm it. I don’t think ethics would be involved at all, I doubt you could get a valid test in an artificially established conditions so you can just observe lions hunting zebras. I don’t know often lions do that, and maybe lions don’t hunt zebras as often as antelopes because they learn to recognize the distinctive pattern of an animal that can kick their head in as an an alternative to running, so that might be another reason the pattern helps zebras survive. The problem I see here is that camouflage may have simply been the default explanation for their coloration without any evidence to back it up. With new evidence about the stripes disrupting insect vision it should all be re-examined.
I don’t think it would be too much of a stretch to present our own mammalian view of zebras as evidence (not conclusive) for disruptive camouflage. If we can observe difficulty in picking out a single animal from a herd, that’s evidence of the effect.
IMO, expecting to find a singular benefit from so overt a morphological feature just seems weird. Nature is sometimes weird of course.
Can we actually do that though? Is it necessary for either humans or lions to distinguish a single animal in a group at a distance? And is it effective close up?
I don’t think evolution is that simple either. The same characteristic could have been beneficial in different ways at different times, or all at the same time. The ‘why’ is rarely something that can be clearly resolved, we just have to keep rethinking and considering the expanding base of knowledge.
Of course for a predator like a lion, it’s crucial to focus on one individual when it makes an attack. That’s the only reason why animals like some birds and fish move (quickly) in huge swarms, and grazing mammals in herds.
This talk of zebra striping as camouflage reminds me of “dazzle” camouflage, used in WWI and WWII. The Wikipedia article describes its zoological origins.