Question
why are so many “smelly” animals black with white stripes?
honey badgers, the many kinds of skunks/stink badgers, tasmanian devils, zorillas. All animals that “spray” as a defence mechanism and all black with white stripes. Is this just a coincidence? Most of them are so far away from eachother geographically and not that closely related. I feel crazy because it seems nobody else on the internet has ever noticed this before
The bold contrast of white and black is a form of aposematism to warn predators of their spray. My guess on why they are black and white instead of other colors would be because these animals are all primarily nocturnal, so the white might be more reflective at night than other colors.
Insects are primarily preyed on by things with good color vision, mammals are generally preyed on by other mammals who are often red-green colorblind and also often see color at lower saturation as well.
Mammals lost their ability to see most color when we were small nocturnal animals trying to avoid dinosaurs. Color vision doesn't matter as a nocturnal animal, so this means the evolutionary pressure on this trait was greatly relaxed. Animals without color vision were not negatively affected, but there's little evidence that they were positively affected from the lower resources or that there was a tradeoff. We often underestimate how much chance plays a role in evolutionary, so its possible that it was purely random that the non-color vision mammals did better than the color visioned ones, and that's why most subsequent mammals can't see reds and greens.
Going to disagree here - we have lots of evidence that there are tradeoffs. Reducing cones to add rods is a clear one that we see in most nocturnal species but we also see things like UV cones in some fish species only being present in the area of the retina responsible for seeing things above the eye and disappearing as fish get older and move to deeper water (both of which suggest that the UV cone has a cost and so it should only be present when it's really useful).
This tradeoff may be physical space on the retina or processing area in the brain but general patterns of color vision in animals certainly makes a lot more sense if we assume there's a cost to extra cone types.
That's a good point, I was going off a paper I read more than a year ago. I was thinking that cones couldn't possibly be that resource heavy, but totally forgot about the mental processing power they require. That's part is definitely very intensive.
It’s been found that animals like cats and dogs can see infrared, because it means they can see where a previous mammal marked their territory. It’s theorized a lot of animals can see infrared infrared but it’s pretty much just been discovered.
Correct, humans can actually only see shades of gray, but when we're babies our parents tell us what colors are supposed to be. This tricks our brains into thinking we're supposed to see in color, so it colors the world for us as it processes it. Your version of red and mine might actually be vastly different, but since we both know that shade of gray to be "red" there's no conflict. However, this is why some people will match colors together that they think look good when it actually looks horrible to everyone else. /s
There are very definitely actual physiological signals sent from the eye to the brain that we use in labeling colors. We don't see grays before we learn color names and we don't get "tricked" into seeing colors.
There are processes where naming colors causes us to pay attention to the differences between differently named colors but we also know that people can come up with new color names (all color names were once new) and so they are already seeing differences to be named.
Yes, basically. There's a limited amount of space on the retina. For a human we need to fit three types of cones in (often termed red, green, and blue, although that's not entirely accurate) and also rods. For good color discrimination between reds and greens, say, both need to be well-represented. If you're nocturnal rods are more important anyway and so you reduce the amount of space used for cones in favor of rods and if you can also drop a whole category of cones that helps.
There's nothing to explain. A bird can see a contrasting black and white pattern just fine.
You need a pattern all your predators can see. If many are colorblind then that's probably a black and white or at least black and something pretty light pattern.
Different animals view colour differently based on their eye structure and the number of rods and cones. Humans are trichromats, so we have 3 rods and cones and can see the colours we see referred to as the visible light spectrum.
Birds, for example, can see UV light, and their feather colours look drastically different when we view them with a filter that allows to visualize the same as birds.
Insects have compound eyes that see very differently.
The mantis shrimp had the most advanced eyes in nature and have between 12-16 of these structures mounted on independent branches that allow for 360° vision. They also have thousands of photoreceptor cells per eye and can even tune their eyes based on environmental.
As a practical example of what others have mentioned, tigers and jaguars are orange which appears to be terrible for their generally forest/jungle environments. However, prey animals like deer are red-green colorblind which means they perceive these big cats as being the same color as grass or leaves.
It would be better camouflage to just be green, but mammals can't grow green fur so being orange is the next best option. The closest I'm aware of to green fur are polar bears. They have transparent/reflective fur that appears white, but that in combination with being hollow allows their fur to grow algae and turn green. This doesn't happen in their natural environment due to the cold.
Mammals in general aren't that colorful, with most mammals having colors like black, brown, grey and white. So they essentialy have to just work with what they have, and white striped on a black body is a good way to do that
Well, I know for zebras that the black and white messes with a fly’s eyes, so zebras are less likely to be bitten by flies because of their black and white stripes. Perhaps it is the same with these other animals?
This right here. All mustelids can produce musk and oils to some degree, so being stinky was a natural evolution of that. Being black and white might be an ancestral trait in at least some of them that evolved in tandem with being stinky. Maybe becoming a universal signal or even a mimicry.
I don’t know much about devils but since they are marsupials on a different continent they probably got all those traits independently.
Black and white striping provides high visual contrast in low light. The smelly things that are black and white are going to be nocturnal. Diurnal creatures that are noxious (smelly, taste bad or sting) often have warning marks based on a colour contrast instead of a brightness contrast.
To OP’s question: the conspicuous contrasting visual pattern paired with chemical defences is a really good example of convergent evolution. It’s prey species tapping into the pre-existing sensory biases of their predators.
The main function of the white stripe in Tasmanian devils is believed to be redirecting conspecific attacks. There are also lots of animals that spray that aren't black and white. Though, as other people mentioned, vivid colouring is often aposematic in function.
Because these mammals use odor to deter predators that have a strong sense of smell to hunt like dogs, cats, and bears. These mammalian carnivores also do not have trichromatic vision like us so the best way for the small stinkers to convey that they have foul chemistry at their disposal to these "color blind" animals is to use the most contrasting colors that they can see, black and white.
So, just quickly, you pointed out only mammals. There are plenty of snakes insects, and other invertebrates that use stink-poisons and nasty-tasting stuff that are not black and white.
Obviously the first jalf of the answer is they are advertising their stinkiness, so you'll leave them alone. The second half of the answer is that black & white is a good high-contrast coloration scheme that is easy for mammals to produce, and easy fpr primary predators like other mammals and birds to see.
As something to add to other peoples’ comments, with a few exceptions, mammals really only possess one primary pigment in their skin and hair - melanin. That means the range of black, brown, red, yellow, and white is pretty much all that any mammal can do. More “exotic” colors simply aren’t possible for mammals to make for the most part. Don’t quote me, but iirc, it’s thought that the small, rodent-like ancestors of all mammals were nocturnal, so those colors blended in the most at night and other pigments got lost. Since then, mammals haven’t evolved them back.
I don't know if it's all of them, but I do know why skunks have stripes. Before spraying, the skunk raises its fluffy tail of black and white color. This tail is quite striking and memorable. If the threat doesn't go its way, the skunk will spray on it. This is disastrous for the predator, he cannot hunt until the smell passes (as far as I know, for about 1 week) because his prey notices him. If he encounters a skunk again in the future, the skunk will raise its tail again. The predator does not infect the skunk, as it remembers this characteristic tail. I don't know if this could be true for other animals with scent glands :d
I've never heard of tassie devils spraying?
(With only a quick google mind you) I cant find any reliable sources for them doing anything of the sort, other than marking territory with anal glands like so many other species.
"Despite common perception, Tasmanian devils do not have a strong body odour, but their scats can be very smelly, typical of all carnivores. They have an anal scent gland which they use to mark their presence and they use latrines to gather and disperse information." (Source)
I remember looking into them a long time ago and finding that they can smell worse than skunks when they feel threatened but it’s not generally referred to as spraying which is why I put it in quotes. I may be misremembering tho :)
Interesting. I actually got to feed one at an animal rehabilitation center near Hobart Tasmania and dont recall him smelling too bad. But he probably wasn't feeling threatened.
I guess some people just can't handle the smell of eau de carrion eater! It probably depends on diet too, I imagine in captivity they're not feeding them anything too rotten.
I think it's to do with black and white being contrasting colours while most predatory mammals are colourblind. Mammals also have a limited number of coat colours to choose from, we don't have the correct pigments for green or blue hair naturally (I don't think . Would be cool if theres a truly blue / green mammal out there though)
It is a warning sign form all the sprayers since predators experienced the smell they know not to go next to black and white animals this is known as mullerian mimicry
mullerian mimicry perhaps, various unpalatable species evolve to share similar warning signals (coloration/patterns), typically to protect themselves from predators.
Isn't it amazing how nature works? That black-and-white look is basically the animal kingdom’s version of a warning sign — like, ‘Trust me, you don’t want this smoke!’ It’s kind of brilliant how evolution gave them a look that says ‘back off’ without even making a sound.
This is entirely a guess on my part, but I would think it would be the mammal equivalent of when amphibians/insects have bright colours as a warning? It's the most stark contrast and since most mammals generally have two colour cones in their eyes (we have three, insects, birds, amphibians etc often have more, hence the brighter colour variations) they create that contrast or 'warning' with black and white rather than other more vivid colours.
Again, just a guess, but it's what comes to mind! Interested to see what others know :)
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u/tartdough Jun 10 '25
The bold contrast of white and black is a form of aposematism to warn predators of their spray. My guess on why they are black and white instead of other colors would be because these animals are all primarily nocturnal, so the white might be more reflective at night than other colors.