Countershading - often referred to as the white tummy in Bengals - is the expression of a dark topside and a light underside. Current Biology published how modern technology has allowed scientists to learn about the camouflaging patterns, including countershading, in dinosaurs. This amazing, beautiful, purposeful pattern has been around for, literally, millions of years.
It may seem odd that a white tummy pattern could be so effective in its purpose that it permeates the animal world from crustaceans to amphibians, reptiles, birds, and mammals. So how does it work, exactly? The diagram to the right from Wikipedia demonstrates how countershading darkens the back and lightens the belly. While the light from above would typically cast a conspicuous shadow, the countershading balances the shadow giving the animal a flat, two-dimensional appearance; therefore, a predator's eye would move past it, not recognizing it as a live animal that would be a tasty snack. Also, animals who are seen from both above and below use countershading to blend into the background from both directions. Imagine a bird of prey stalking a cat in the trees; the dark spotted top coat would blend in with the tree bark. Likewise, if a wild dog were looking up into the trees from the ground, the light belly would blend with the light of the sky. In more ways than one, countershading helps animals avoid detection by other animals which is beneficial as both predator and prey.
How do we know this pattern is useful? One is by the sheer number of species that have evolved to have a countershading pattern. In addition, several studies have been done over the years, and they have all concluded that "countershaded prey avoided predation more effectively than prey that were uniformly shaded or those that display a dark ventral surface" (Kamilar, J.M. Int J Primatol (2009). Interestingly, though, we also see further evidence in species who have evolved to have reverse countershading. Both the Honey Badger and the Skunk display reverse countershading - a light topside and a dark underside. These animals have strong natural defenses and do not hide from predators. They want to be seen. The reverse countershading pattern is a method of warning other animals to stay away.
If countershading helps animals become two-dimensional in the daylight, how would a nocturnal animal have any benefit for countershading? A study on primate countershading published in the International Journal of Primatology discovered, contrary to the original hypothesis of the study, that "nocturnal primates exhibited higher levels of countershading" than diurnal primates. Furthermore, the study found that the intensity of the countershading increased in smaller primates who hunted mainly in trees over larger primates who spent more time on the ground. Nocturnal animals are more active when moonlight levels are at their highest; therefore, they, too, reap the benefits of camouflage by night.
Ultimately, the study on primates proves that small, tree-dwelling, nocturnal primates have the strongest expressions of the countershading pattern within the primate world - and that brings us to the feline world and, more specifically, the Bengal cat and the Bengal standard. While cats are not primates, the purpose of the pattern is the same for small tree-dwelling cats as it is for small tree-dwelling primates. All Bengal standards, regardless of registration, reference the desired look of a nocturnal wildcat. Most standards specify a tree-dwelling, nocturnal wildcat; some standards even name the Leopard cat as the model. The countershading pattern, displayed in the intensity of a Leopard cat, is without a doubt a unique trait to the Bengal breed. It is unlike all other breeds as the Bengal cat is the only domestic cat to emulate a tree-dwelling, nocturnal cat.
As the Bengal breed begins to have more and more cats with a countershading pattern, it is important to be able to identify it, not only in its most pristine form but also in its developmental stages. The countershading pattern is not created with a simple dominant or recessive gene. It is thought to involve a complex web of genes, proteins, and genetic switches. Agouti signals different shading by creating proteins that tell the cells to produce dark or light colors. Furthermore, there is a genetic switch that must activate the belly skin cells of the embryo to display the white countershading pattern. Let's go over that one more time. For a white countershading pattern to exist, first the cat must have the right genetics. Next, it must create the protein to control the right color of pigment in the hair. Finally, a genetic switch must trigger at just the right time in embryonic development for the countershading pattern to exist in a white that is equal to that on wildcats. Let that soak in; a lot must happen to get this right. Because key elements of this genetic puzzle had to come from the Leopard cat, it will take time and careful selection for Bengal breeders to have consistently white countershading patterns on their cats. It is a work in progress - hard work that furthers the development of the Bengal breed to achieve the goal of emulating the appearance of a nocturnal, tree-dwelling cat.
What does the countershading pattern look like in development? The countershading pattern in development on a Bengal cat can express in a variety of ways. First, it may not be white - but either cream or gray. Any lightening of the underbelly indicates that some of the three steps - the genetics, the protein, and/or the switch - are present in the cat, but not all. We have noticed that Bengals with a Leopard cat white countershading pattern has a slight gray tint to the base of the white hairs. When that gray travels too far up the hair shaft, the countershading pattern appears gray. While this isn't perfect, it is a significant step towards the ideal. On the other end of the spectrum, when too much yellow pigment is signaled into the developing tummy hairs, the pattern appears cream or buff. Again, this isn't the ideal, but it is a significant step forward from a cat whose tummy hairs are the same color as their body hairs.
Another developmental variable is the size of the countershading pattern. While the Leopard cat typically has a countershading pattern that comes up the sides high enough to be seen while walking, not every Bengal's countershading pattern reaches that ideal. Some are just white along the center line under the tummy, so one must look at the underside to see this development. Regardless, this is still a significant step towards the ultimate goal. What appears to be the most difficult place to retain white on a Bengal countershading pattern is at the collar. Often, a Bengal will be white under the chin, and white between the legs, but the pattern around the collar is cream.
When pursuing the white countershading pattern, it is essential not to confuse this beautiful, purposeful pattern with random areas of non-pigmented white. The most significant distinction between the two is pigmentation. On areas on non-pigmented white, the color of white is extreme. If you part the hairs, they will be white from root to tip and the skin beneath will be pink. In contrast, even the whitest countershading patterns will not have white hairs from root to tip; though the hairs may appear white to the naked eye, upon careful inspection, they will either have gray at the base or they will have some degree of yellow pigmentation. When trying to decide between non-pigmented white and the white of a countershading pattern, hold up a white piece of paper next to the countershading pattern to help identify either the gray at the base of the hairs or the yellow pigment within the hairs.
Another way to distinguish countershading from areas on non-pigmented white is to look for pattern within the countershading area. Some portion of the countershading pattern will have spots within it. It is a challenge to get black pattern to display throughout the whole of the countershaded area, but again, look at the white hairs if in doubt. They will either have a hint of gray pigment at the base, or they will have a slight yellow pigment throughout the hair, therefore, making them not pure white. The underlying skin of the countershaded area will have pigment as well as the hairs. The picture of the cat on above and to the right shows an obvious area of non-pigmented hair on his throat - otherwise know as a locket. The skin beneath the locket does not have any pigment either. Lockets involve totally different, much simpler genetics. We must be careful to avoid crediting these non-pigmented lockets as having any connection to the countershading pattern; furthermore, we must also accurately learn to distinguish the difference between them. Lockets are nondesirable and penalized in the show hall while countershading is desirable and difficult to achieve. Because it is a unique pattern distinctive to tree-dwelling, nocturnal wildcats, countershading should be rewarded. Confusing the two is detrimental to breed development.
To add to the many complications in developing a countershading pattern, the pattern often displays in young kittens but disappears upon maturity. This is likely due to the genetics of the original Felis wildcats from which all domestic cats descend. The Felis cats are ground-dwelling cats and do not have as strong a need for a countershading pattern. Often the kittens of ground-dwelling cats are born with a countershading pattern, but it disappears with age. Since it wasn't needed for species survival those without countershading patterns survived and passed their genes on. Perhaps some of the necessary components are in the Felis cats and help the Bengal get closer to its goal; however, we rely upon the Leopard cat to unlock the web of genetic requirements in the right order.
One day it would be nice to see all Bengals display this unique and magnificent pattern. But until then, we should treasure the ones who do. Encourage Bengal breeders to keep moving forward with Bengals that express partial patterns. Right now, all we can do is hope our throw of the genetic dice lands in our favor, but perhaps, one day, we can throw those dice with more educated precision.
The white countershading pattern is a pattern that displays most vividly on nocturnal animals who live and hunt in the trees by moonlight. It is a pattern that relies upon Leopard cat genetics to fully express in the Bengal breed. It is a pattern that manifests differently on the Bengal than on any other domestic breed. Therefore, it is a pattern we should value and foster within the breed.