black panther jaguar
Science

Melanism in Big Cats: What Makes the Black Panther Black?

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Black panther jaguar
Black jaguar – Image by katerinavulcova from Pixabay

A couple days ago, my friend texted me while they were looking at a black panther exhibit at the art museum and asked me what kind of cat black panthers actually are. I had to break it to them–and now to you–that there really isn’t any such thing as a black panther. The name “black panther” is applied to individuals of several species of wild cat which are all black due to a rare genetic condition called melanism. Most black panthers are actually leopards or jaguars, both of which are normally yellow with black spots [9].

What is melanism?

Graphic showing which felids can be melanistic
Many cats come in black [4]

Melanism is a rare genetic mutation that causes animals to have black skin and fur/feathers/whatever when members of their species typically do not [1, 3, 4, 7, 9]. The mutation causes the affected animals to produce an excess of the dark color pigment melanin [1, 2, 7]. Lots of animals can be melanistic, including pigs, cows, mice, butterflies, snakes, lizards, and snails [2, 4, 7]. Melanism is more common in felids than most taxa, however [1-3, 7]. 15 of the 40 species in the genus Felidae are known to exhibit melanism [4].

Melanistic cats have black fur all over their bodies but may still have some of the patterning or their “normal,” or wild-type, brethren. For example, black leopards still have rosettes which are even darker black [7, 9], and some melanistic Asian golden cats have a white mark on the underside of their tails [4].

Melanism mutations have cropped up at least eight separate times in the cat family tree [3]. These different mutations don’t all work exactly the same way. Mutations in the ASIP gene are recessive, meaning that a cat has to inherit the mutation from both parents to be black [2, 7]. The ASIP protein normally inhibits eumelanin (dark pigment) production, and these mutations make the ASIP protein non-functional [2, 7]. Leopards and Asian golden cats inherit melanism as a recessive ASIP mutation [2, 3, 6-9].

Mutations in the MC1R gene are dominant, so a cat can inherit either one or two copies of the mutation to be melanistic [2, 7]. MC1R promotes the production of eumelanin, and the mutations increase its activity [2, 7]. Jaguars and jaguarundis inherit melanism as a dominant MC1R mutation [2, 9].

How many black panthers are there?

In general, the rate of melanism in the felid species that have it is thought to be around 10% [3, 9]. However, the actual percentage varies widely depending upon the species and specific population [1, 3, 4, 8]. Leopards range throughout Africa, up through Asia, and as far north as Siberia. In Africa, they are almost never seen in their black panther form, but in Malaysia, the exact opposite is true–almost all leopards are black [3, 4, 7-9]. Southeast Asia in general has about half melanistic, half wild-type leopards [3]. Servals are more likely to exhibit melanism in the East African highlands and the Tsavo ecosystem of southeast Kenya [1]. While most species have fewer melanistic cats than wild-type, 80% of jaguarundis are melanistic [2, 4].

Melanistic (A) and wild-type (B) tigrinas [4]

It’s difficult to get an accurate count of how many wild cats there are in the world to begin with, due to their stealth and dwindling habitats. Counting black cats has its own particular challenges. Sometimes reports of a “black panther” are ambiguous or a case of mistaken identity [5]. There is still debate about whether or not melanistic cougars actually exist for that reason [5]. Because melanistic wild cats are rare in most environments, people are more likely to take notice of them and tell somebody if they see one, possibly inflating their numbers [1].

Why are only some big cats melanistic?

The evolution of melanism in felids is still up for discussion among biologists. The most prominent theory is that melanism is so common among cat species because it helps camouflage them in dark, forested places [3, 8]. As ambush predators–and sometimes prey for bigger animals–most cats specialize in stealth, so camouflage is important. This would explain why melanism is more common in cats in jungle habitats and very rare in open grasslands where a black cat would really stand out [3, 8].

Researchers have found some other possible benefits to being a black panther, too. Dark coloration may aid in temperature control in high-altitude or cool, moist forest environments [1, 9]. Research in dark-colored birds has shown that they are resistant to feather-degrading bacteria [3], so there is a possibility that melanistic felids have some additional immunity to disease [3, 8].

There may be some downsides to that glossy black coat, however, even in favorable habitats. Black leopard pairs have smaller litter sizes [6], although the melanism mutation itself appears to have no ill effects [7]. Graipel et al. found evidence that melanistic cats in some species may have a disadvantage in communicating with their peers because the lack the white spots behind their ears or on their tails characteristic of their species [4]. Wild cats use these spots to send signals to each other at short distances, silently, without alerting prey or predators [4]. This is more important for some species than others, depending upon their habitat and whether they are more active when it’s light or dark [4]. Some felids don’t have these spots at all [4]. So it’s more advantageous to dress in black for some cats than for others.

Miniature black panthers

One of the felid species that exhibits melanism is the domestic cat, Felis catus [7]. That’s right, you might have a black panther of your very own! Not all black housecats are melanistic, however, because coat color genetics are complicated. Melanistic cats will be solid black, absolutely no white hairs, and their skin will be black as well. Also, fun fact: melanistic kittens often have “ghost” tabby stripes that typically fade with time, like the black leopard’s shadowy spots [7].

Sources

  1. Adkins, B. (2019, May 12). Melanism in servals. Sheldrick Wildlife Trust. https://www.sheldrickwildlifetrust.org/news/wilderness/melanism-in-servals
  2. Eizirik, E., Yuhki, N., Johnson, W. E., Menotti-Raymond, M., et al. (2003). Molecular genetics and evolution of melanism in the cat family. Current Biology, 13(5), 448-453. https://doi.org/10.1016/S0960-9822(03)00128-3
  3. da Silva, L. G., Kawanishi, K., Henschel, P., Kittle, A., et al. (2017). Mapping black panthers: Macroecological modeling of melanism in leopards (Panthera pardus). PLoS One, 12(4), e0170378. doi:10.1371/journal.pone.0170378
  4. Graipel, M. E., Bogoni, J. A., Giehl, E. L. H., Cerezer, F. O., et al. (2019). Melanism evolution in the cat family is influenced by intraspecific communication under low visibility. PLoS One, 14(12), e0226136. https://doi.org/10.1371/journal.pone.0226136
  5. Hartwell, S. (n.d.). Mutant pumas. Messybeast. http://messybeast.com/genetics/mutant-pumas.html
  6. Robinson, R. (1970). Inheritance of the black form of the leopard Panthera pardus. Genetica, 41, 190-197. https://link.springer.com/article/10.1007/BF00958904 [Abstract]
  7. Schneider, A., David, V. A., Johnson, W. E., O’Brien, S. J., et al. (2012). How the leopard hides its spots: ASIP mutations and melanism in wild cats. PLoS One, 7(12), e50386. doi:10.1371/journal.pone.0050386
  8. Sunquist, F. (2006, December 1). Malaysian mystery. The National Wildlife Federation. https://www.nwf.org/en/Magazines/National-Wildlife/2007/Malasian-Mystery
  9. Zaccaria, J. (2019, October 28). Wild cats 101: Black cats and more on melanism. Panthera. https://panthera.org/blog-post/wild-cats-101-black-cats-and-more-melanism

Published October 8th, 2023

Behavior

Why do cats purr?

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Brown tabby cat in lap
Image by Hans Braxmeier from Pixabay

What could bring more joy than a purring kitty curled up in your lap? And there are so many different kinds of purrs. Some cats purr like a lawn mower engine, and some are so quiet you could barely hear them with your ear on their chest. Purring is a uniquely feline behavior. We associate it with happy kitties, but cats actually purr under a lot of different circumstances. This rather odd sound must serve a purpose besides being adorable. So why do cats purr?

Anatomy of the Purr

First things first: what even is purring? As someone who used to try it for myself as a child, I promise it doesn’t come naturally if you aren’t a cat. There was a lot of debate about how cats purred for a long time. One prominent theory was that the purring sound came from a change in the cat’s blood flow [1, 4, 6]. Now, biologists are generally agreed that cats purr using the muscles of their larynx and diaphragm [1, 3-5, 7]. By vibrating their larynx, which in turn vibrates their hyoid bone [5], a cat causes the air in their throat to vibrate as well, creating the sound we know as purring [1, 6].

Most vocalizations can only be made when exhaling. It just makes sense. You need air in your lungs to push through your larynx to talk, sing, laugh, etc. The same is true of other animals. However, cats can purr on the exhale and the inhale, which is what enables them to purr constantly [1-5, 7]. This is due to the continual vibration of the larynx as they breathe in and out through it [1].

Cats Purr to Communicate

Cats first start to purr by the time they are a week old [1, 2, 4]. The purring of her newborns may signal to a queen their location and wellbeing [1, 2, 4]. It is thought that each kitten has a unique purr their mother can recognize so that she can tell which of her babies is communicating with her [2].

Queens will also purr for their kittens [5, 6]. One reason may be to provide a tactile cue to help blind and deaf newborn kittens locate the milk supply [6]. Even though very young kittens can’t hear the purring yet, they can feel the vibrations because they are, ideally, never far away. Alternatively, the mother’s purring may disguise the soft mews of the kittens from the ears of predators [5]. Whatever the evolutionary reason, purring cements the bond between queen and kittens [5].

Some adult cats purr when feeding, possibly a throwback to that kittenhood behavior [1]. Cats may also purr to inform their person that they want their food, now please [1]! The purr of solicitation sounds different from the snuggly purr [1]. What’s the difference? It’s hard to say for sure. Our lack of knowledge about how cats communicate with each other makes it harder to understand the nuances of how they communicate with us.

One thing that’s certain is cats in the wild purr when they groom each other [1]. Grooming is an important part of a cat’s daily life and a positive social interaction between cats who have a bond. Perhaps this comes closest to the contended purring of a cat that is lying in a warm lap or being petted.

Mother cat and kittens in barn
Queens and their kittens purr to communicate – Image by Franz W. from Pixabay

Healing Vibrations

Cats don’t just purr for happy reasons. They sometimes purr when they’re stressed, scared, injured, or dying [1, 3-5, 7, 8]. Cats have sometimes been seen lying alongside another, injured cat, both purring [7]. This is called “purr therapy” because the purring is believed to be a way of comforting the injured cat [7]. In stressful situations, purring can serve as a method of self-soothing [7]. However, it may be an even more powerful tool than that.

Cats purr at a frequency of 20-150 Hertz [1, 3]. These low-frequency vibrations have demonstrated healing benefits [1, 3, 4, 7, 8]. 25 and 50 Hz frequencies promote bone growth and fracture healing [8]. 100 Hz has therapeutic use for pain, wound healing, swelling, and difficulty breathing [8]. It may seem far-fetched, but bones do respond to pressure by hardening [1, 7]. And there is a good evolutionary reason why cats might vibrate their way to good health.

Cats are ambush predators. This means they spend a lot of their time resting and waiting in-between hunts. Purring could have evolved as a low-energy way to stimulate their muscles and bones while stationary [3, 7]. Then their bones wouldn’t weaken or become brittle over time from lack of use [7]. Interestingly, researchers have proposed just such a fix for astronauts. Muscle atrophy and bone density loss are a big problem on long space missions where the lack of gravity prevents normal exercise. Vibrating foot plates have been suggested to stimulate astronauts’ bones and prevent them from losing density [7]. It seems the cats had that figured out a long time ago.

Do All Cats Purr?

Probably not, but it kind of depends upon how you define purring, apparently. Once upon a time in the early 1800s, biologists believed that cats could either roar or purr, but it was impossible to do both [7]. This is how cats came to be divided into the “big cats,” or subfamily Pantherinae, and the “small cats,” subfamily Felinae [6, 7]. Although most big cats are larger than most small cats, those names are actually a misnomer, since the smallest of the “big cats,” the clouded leopard, is smaller than the biggest of the small cats, the puma [7]. The basis of the division on roaring vs. purring is also probably inaccurate.

Two sleepy bobcats
Housecats aren’t the only ones that purr! – Image by Amber Stevens from Pixabay

The Pantherinae cats have a rope of tough, flexible cartilage where the Felinae have only the hyoid bone [5, 6]. This gives the larynx greater flexibility so that roaring is possible, although lions are the only ones to make regular use of this ability [5, 6]. Does this mean they can’t purr, though? These days, biologists tend to believe than most cats can purr, or at least something like it [3, 7]. Some call it a purr-like vocalization or a hum rather than a true purr [3, 4, 6].

Even granting that most cats can actually purr, some of the Pantherinae are usually believed to be exceptions: lions, leopards, jaguars, tigers, snow leopards, and clouded leopards [7]. But that may yet prove untrue. The anthropologist and animal behaviorist Elizabeth Marshall Thomas suggests that big cats may reserve purring for their cubs and that is why people think they don’t purr at all [6]. We simply aren’t around when they do.

Works Cited

  1. Dowling, S. (2018, July 25). The complicated truth about a cat’s purr. BBC Future. https://www.bbc.com/future/article/20180724-the-complicated-truth-about-a-cats-purr
  2. Edwards, A. (2006). The ultimate encyclopedia of cat, cat breeds, and cat care. Hermes House: London.
  3. Lyons, L. A. (2006, April 3). Why do cats purr? Scientific American. https://www.scientificamerican.com/article/why-do-cats-purr/
  4. Science Reference Section. (2019, November 19). Why and how do cats purr? Library of Congress. https://www.loc.gov/everyday-mysteries/item/why-and-how-do-cats-purr/
  5. Stewart, D. (1995, April 1). Do lions purr? And why are there no green mammals? The National Wildlife Federation. https://www.nwf.org/Magazines/National-Wildlife/1995/Questions-and-Answers-About-Wildlife
  6. Thomas, E. M. (1994). The tribe of tiger: Cats and their culture. Simon & Schuster: New York.
  7. Venton, D. (2015, May 8). Why do cats purr? It’s not just because they’re happy. Wired. https://www.wired.com/2015/05/why-do-cats-purr/
  8. von Muggenthaler, E. (2001). The felid purr: A healing mechanism? The Journal of the Acoustical Society of America 110(5), 2666. https://doi.org/10.1121/1.4777098

Published February 7, 2021

Updated June 20, 2022