The differences between one cat and another are relatively small. While dogs can range from a Chihuahua to a Mastiff, there is no such range in the domestic cat. Pet cats average between 8 and 11 pounds in weight; are roughly 10 inches tall, and most are roughly a foot and half (18 inches) long; the tail usually adds an additional foot or so.

It is the extra lumbar and thoracic vertebrae in the cat's spinal structure that give the animal uncanny flexibility and spinal mobility. Humans only have 5 lumbar vertebrae; cats have 7; humans have 12 throacic vertebrae and cats have 13. (Tail lengths vary, so the number of caudal vertebrae varies as well.)

Cats have free-floating clavicle bones; ours are stationary. It is that specific anatomical feature that enables cats to pass through any space they can fit their head through. You and I must use distinctly different traits to make such determinations!

There are other distinctions to the skeletal structure of the domestic cat. These are well-designed predators, with specific canine teeth for killing prey; they are small, long and fairly close together (as compared to those of large cats). After landing its prey, the domestic cat inserts its two canine teeth between two vertebrae of the prey. This severs the victim's spinal cord, paralyzing the prey and/or causing its death. The dimensions of the teeth versus the spines of the small rodents they hunt for are complementary to each other.

For tearing meat, domestic cats have a carnassial or scissor pair of molars on each side of their mouth. These teeth literally shear meat into small pieces. Cats do not chew well because of how small their specifically adapted teeth are, so the ability to tear their food into pieces that are both comfortable to swallow and easy to digest is critical.

Cats walk on their toes, not on their feet. This is common to most other mammals, including dogs. This is referred to as digitigrade locomotion. . (Humans, bears and some other exceptions walk on the soles of the feet.) All felines ‘directly register’, which means that when they walk they place each hind paw directly in the footprint of the (corresponding) forepaw. This trait means cats evade larger carnivores who consider them prey, since they leave very few visible tracks and make far less noise as a result. Animals that directly register can navigate rough terrain far easier than those that don't.

Each of those surefooted toes has a claw; those claws stay sharp because they remain sheathed until the cat voluntarily extends them. Front paws are usually sharper than hind paws, and cats can extend the claws on one foot and not the others. Sheathed, there is no tell-tale noise that might alert (and spare) prey, and no clicking on tile floors to give away their location. In the U.S., declawing domestic cats became a fairly common practice from the 1950s onward; today many consider the practice mutilation.

Like dogs, cats have carpal pads, located on the inside of the wrists of the front paws. While veterinary science hasn't specifically determined the function of this bump (often referred to as a sixth finger) it may help stabilize the cat when jumping or leaping, or eliminate skidding during those activities.

Cats normally have five claws on their front paws and four on their back paws, but there are breeds where polydactylism is common, particularly those originating in the New England states of America. Maine Coons often display this trait; some of these large cats have six, eight or ten toes on each foot.

Differences between house pets and wild cats

Carlos Driscoll, a doctoral fellow at Oxford University, conducted research on cats and their wild ancestors while at the U.S. National Cancer Institute's Laboratory of Genomic Diversity. Using genetic material from 979 domestic cats in diverse places ranging from Scotland to Mongolia, his team of researchers also gathered DNA samples of the last populations of truly wild cats: Felis silvestris silvestris, Felis s. lybica, Felis s. ornate, Felis s. cafra and Felis s. bieti. — wild cats of Europe, Africa and the Near East, Central Asia, the Sahara desert and China's desert, respectively.

The study determined that all domestic cats come from the Near East, and that they are all related to each other. They all probably descend from the Near East's wild cat Felis s. lybica.

Sight

The ability of cats to see in the dark has fascinated humans for centuries. When we are groping around in the dark, bumping our toes as we try and remember where we put the flashlight, our cats see just fine. We humans need about 84 percent more light than they do to see clearly; that means they need only one-sixth the light level we require. Their slit pupils focus bright light, and they will expand dramatically in low light. Their tapetum lucidum (a layer of tissue immediately behind the retina) reflects any light that passes through the retina back into the eye, which increases their ability to see in dim light. Research shows cats have poor color vision; while most see only blue and green, some cats have been able to distinguish between red and green.

Hearing

Cats' hearing puts most other animals' abilities to shame, and leaves human beings thinking they have a touch of the supernatural. It is more than just an enhanced ability to hear sounds — cats can hear high frequency sounds that we cannot. Additionally, cats have a remarkable ability to locate the source of a sound.

Cats' prey are small animals that make barely discernable noises which are clear as a bell to the cat lying in wait, perfectly still, angling those ears to hear every breath of the field mouse, every leap of the squirrel. They can filter out the other noises of the forest, tuning their hearing to the smallest noises and not moving a muscle until they have ‘located’ their prey. In other words, they hunt by lurking, and successful lurkers are those who can hear their prey clearly.

We humans are capable of hearing sounds up to approximately 20,000 cycles per second in the prime of our lives; at our retirement party, most of us will hear only about 12,000 per second. Dogs hear up to 40,000 cycles per second, hearing many things we simply can't. Cats hear up to an amazing 100,000 cycles per second, the frequency of mouse sounds.

That ability is how they often seem to us to ‘predict’ events; it is more likely they are simply hearing things we don't and reacting appropriately.

Smell

Your cat's sense of smell is about 13 times greater than your own. That difference enables it to recognize a great many things we don't have any consciousness of, notably the spoor left by a rabbit crossing your back yard early this morning.

Once you understand how remarkable the cat's sense of smell really is, you'll understand a great deal more about its behavior. Many foods have little or no odor when refrigerated; if you present your cat with cold food, it may refuse to eat what it cannot identify by smell. Warm things up and your cat may become positively ravenous! Think lukewarm, and do test first on your wrist until you're sure of the microwave setting.

In addition to their enhanced olfactory qualities, cats have a unique feature on the roof of their mouths called the Vomeronasal organ. Opening the mouth, the cat draws the odor it has already inhaled down into its mouth to expose this organ to the scent. It pauses and stops breathing to do so. This combination of motions and expression is known as the flehman response.

Coat colors

Melanin is the substance responsible for the color pigmentation of skin, hair and eyes. In cats, melanin granules of different sizes and shapes are deposited in the hair shafts in differing arrangements, creating a variety of colors. There are numerous genes that cause variation in the density of the melanin granules, which creates still more colors.

Melanin comes in two varieties: eumelanin, responsible for black pigmentation, and phaeomelanin, which produces colors in the red/orange/yellow range. Black based colors — those created by eumelanin — have the most variation.

The common names used in biology for these colors are the names used to identify those colors in cats as well.

Black pigmentation when dense produces black cats; when dilute it will create blue cats.

Black pigmentation also produces brown cats, when dense that creates chocolate cats; when dilute, lilac.

Black pigmentation also produces light brown cats, when dense that creates cinnamon cats; when dilute, fawn.

Red based pigmentation produces orange cats, when dense that color creates red cats; when dilute, cream.

The black gene, when mutated, produces Chocolate and Cinnamon, which are believed to be due to a smaller number of eumelanin granules on each hair shaft. Chocolate may also be called Chestnut. Genetically speaking, chocolate is recessive to black and cinnamon is recessive to chocolate. These colors are thought to be due to a smaller number of eumelanin granules in the hair shaft. The Chocolate color is a medium to dark brown A If If the gene for dense coloration is mutated, it produces Blue, Lilac and Fawn. All thress of these colors appear to be created by a clustering of the melanin particles on the hair shaft, referred to as dilution or Maltesing. Blue is the dilute form of Black; it is usually presents as various shades of gray. Lilac is the dilute form of Chocolate; it is described as dove or light taupe gray, and is sometimes called frost or lavender. Fawn is the dilute form of Cinnamon; it is described as “coffee and cream” or caramel color. Dilution is recessive to dense coloration.

Much less variation comes from the phaeomelanistic colors. Red is usually described as orange or marmalade, but some red cats are pale enough in color to be called yellow. Cream is the dilute form of Red, and is described as a buff color.

The popular Tortoiseshell pattern is the direct result of carrying one red gene and one black gene. All Red genes are carried on the X chromosome; for this reason it is sex-linked. Males normally only have one X chromosome and so if a male carries the Red gene at all, he will be Red. Females have two X chromosomes; if both X chromosomes carry the Red gene, then the cat will be Red. However, many females carry the Red gene on only one chromosome, which allows the black-based pigmentation to show through in patches. This combination of red and black is called Tortoiseshell. A typical Tortoiseshell is a patchwork of black and orange, usually in a random pattern. The Tortoiseshell can be modified by dilution, which gives a patchwork of blue and cream rather than black and orange. Such dilute Torties are usually called Blue-Cream, while the black patches of a Tortie may actually be any of the black-based colors. That's where Chocolate Torties and Cinnamon Torties occur; if dilution is also present, a Lilac-Cream Tortie or a Fawn-Cream Tortie will be the result.

Tail

Your cat's tail contains roughly 10 percent of all the bones in its body, along with four to seven paired nerves and a set of scent glands. It is a sensitive part of the feline body, plays a role in the cat's ability to balance and communicates mood.

Sprint

Amazingly, the sprint potential of the average house cat can be anywhere from 5 to 30 miles per hour. Needless to say, most cats will perform somewhere in the middle range, and while we measure in miles per hour, such accelerated sprints cannot be maintained for anywhere near that long. The Egyptian Mau is without a doubt the fastest sprinter; they are the breed that set the top of the scale at 30 miles per hour. The reason for their sprinting prominence lies in their anatomy. Thanks to a flap of skin from their flank to the back of their knee, they have an excessively long stride as compared to other cats. In addition, the back legs of a Mau are longer than the front legs while the overall body is small and lithe. These factors combine to produce speeds other house cats cannot match.