Cat Anatomy

Cat Anatomy - Photo by Curious Expeditions.

The picture above was taken at Wax Anatomical Models at La Specola in Florence, Italy. The photograph is published under a creative commons license kindly granted by the photographer. I am sorry if it is a bit gruesome. It is pretty well all I could find as an illustration that was licensed for publication.

Cat Anatomy is a very wide ranging subject. The anatomy of a cat is very similar to human anatomy.

If you were writing a biology book for students of biology you would go through every part of the a cat's anatomy in some detail. It would be similar to writing a book about the human anatomy. It would be a thick book and pretty boring for your average internet surfer. So, how do you limit such a big subject and make this post meaningful? The answer I think lies in doing two things:

1. Having a quick general look at cat anatomy - an overview and;
2. Focusing on the areas of cat anatomy that are particular to the cat and of particular interest making appropriate comparisons to human anatomy. This is what I have done here. Most of the differences concern the advanced senses and sensory organs of the cat.

There are links to lots more information within each section.

Overview

Cat Anatomy

Cat Skeleton - photo by Sophie.

The major organs of a cat are very similar if not identical to human organs. The above image is reproduced under a published under Wikimedia® creative commons license license = Attribution-ShareAlike License, kindly granted by the copyright holder Surachit. This is a cropped image as allowed under the creative commons license. Here is a better image of the cat skeleton added later:

Cat Skeleton - photo copyright Michael @ PoC

See the above image in large format.

You can read lots more on the cat's skeleton and see the above image in large format by clicking on the following link: CAT SKELETON.

The first thing I think about when I think of cat anatomy is that it must be very similar to ours because a lot of testing for a range of reasons takes place, sadly, on cats. These are tests to see reactions to products that are designed for human use for example animal testing for cosmetics. That tells us a lot about cat anatomy and about us! 

Cat anatomy consists of all the organs found in a human as the diagram above indicates. Of course the cat walks on all fours and the cat walks on his or her toes - they are digitigrades.  This is one reason why it is cruel to chop parts of their toes off for our convenience. I am talking about cat declawing.

Some humans also walk permanently on all fours. There is a family or two in Turkey that walk this way for example. This may be due to a mutated gene rather than simple preference or habit.

A cats skeleton has 244 bones (humans: 206) and 506 muscles apparently. The major difference is accounted for in the cat's tail where there are 19-28 bones.

Although the organs found in the head are the same as ours that part of the cat's anatomy that deals with the senses are more highly developed or specialized throughout the range of senses. The cat's ear flaps (pinnae) are much more mobile, for example (see CAT EARS). The cat's sense of smell is more sensitive and is a major part of the way of life of a cat (see CAT'S NOSE for lots of information on that). They even have a special organ that boosts odor reception (see below). Their eyes are both worse (less good at registering color) and better, being better adapted for night vision (see below) as they are crepuscular (dawn and dusk) hunters. Their eyes, indeed all of cat anatomy, is designed for efficient survival.

Things that cats lack, and which we have, are sweat glands and eyelashes. Eyelashes are designed to keep liquids and objects from the eyes. Cats have less need for them it would seem as the fur protects the eye from liquids. They also have a full inner eyelid which you can see sometimes pulled half over the eye when a cat is about to go to sleep. It can cover all the eye.

Cats do have sweat glands in their paw pads, however (see below for reason).

Cats Jaw and Teeth - Photo montage by Michael @ PoC

Jaw and Teeth

Perhaps a good place to start with cat anatomy is at the front!! Seriously though the cat has a strong bite as some of us will be aware. The two large and strong muscles in the head that operate the jaw are the Masseter and Temporalis. The same muscles are present in a human. Both muscles are for mastication (chewing). The purebred cat's head shape has been altered through selective cat breeding. The modern Siamese has a long head, some say rat-like and the contemporary Persian's head is flattened at the front.

Recent research findings indicate that the smaller the animals brain the stronger the bite as a generality as there is more room for larger muscles. This probably explains why the domestic cat has a stronger bite than the human. But I am not saying that the cat is more stupid. Less ability in terms of reasoning, yes, but more in other forms of intelligence such as spacial intelligence and senses - cat intelligence.

The now extinct saber tooth tiger had a weaker bite than modern big wild cats as it probably used its large canine teeth to severe arteries. Modern lions and tigers such as the Bengal tiger and White Siberian tiger suffocate large prey by strangulation clamping their jaws around the preys windpipe. Click on this link to see a comparison of the bite strengths of the domestic cat to other animals including wild cats.

Adult cats have 16 teeth on the top jaw and 14 on the bottom. Click on the following link to read more about cat teeth: CAT TEETH.

Cat Anatomy - Cat Muscles - photo montage by Michael @ PoC

Muscles

The cat has three types of muscles some of which are fast twitch. These fast acting muscles combined with it's flexible skeleton provide the cat with superior athletic abilities. We are all aware these abilities.

Read lots more on this page: CAT MUSCLES.

Paws and Claws

Cats have 5 toes on the front paws and 4 toes on the back paws. This is written into cat association breed standards as cats can sometimes have more toes (up to 7 but the Guinness Book of Records records a cat with 27 toes!) than the regulation number. These are called Polydactyl cats or Hemingway cats after the cats kept by Ernest Hemingway whose cats were all of this kind. See American Polydactyl Cat.

Polydactyl cat photo by JP Puerta (Flickr)

Hemingway's home in Florida is a museum and the descendants of his cats still roam the grounds. There are apparently 60 cats, 30 of which are Polydactyl.

These are not a special breed of cat just cats with more toes than normal due to a congenital physical abnormality. Humans can have more than five fingers or toes so this condition cuts across species. See also Polydactyl Cats and Tootsie a Maine Coon with many toes!

There are 6 separate pads on each paw. Cats paw pads contain sweat glands. The primary reason for a cat to secrete sweat from her/his paw is to improve traction (adhesive friction) between the paw pad and the surface. It helps prevent the pads from slipping on certain surfaces. When a cat is nervous (for example at a veterinarians) she'll sweat from her paw pads. You'll see the paw prints on the vet's table. This happens as the cat is preparing to run! We sweat when we are nervous too (clammy hands waiting for an interview, for example).

Cheetah speed is enhanced by semi-retractable claws, which provide added traction.

Photo by almostlindy

Objects can get stuck in between pads, which can cause irritation. Fur grows in between pads. For long haired cats like the Maine Coon (semi-long) or the Persian the fur between the pads can be long and stick out (see above). The fur is there to keep the feet warm (no shoes).

Cat claws - photo by •Ronnie 

Many animals have claws, which are used for digging, climbing and added traction when running (like spikes on an athlete's shoes). In cats claws have added value helping the cat to catch and hold on to prey. Claws also are weapons in self defense. They are sickle shaped and very sharp at the tip. They renew themselves to help keep them effective and can be withdrawn into a pouch to protect them when not required (i.e. give them a longer life).

A new claw grows under the old and the old sheath eventually falls off encouraged by scratching (see above). Many animal behaviorists and experts say cat claws should be trimmed but it seems this cat interrupt the shedding of the old claw husk in the renewal cycle and lead to problems such as infection. It is best to leave well alone and make provision in another way for damaged furniture (simply accept it is the best way). See declawing alternatives, please.

If they are trimmed for the sake of children the claws should be checked for health regularly. The children should also be trained to interact with a domestic cat on the cat's terms. The same goes to adults. Obviously declawing is a complete no-no. That said many millions of cats are declawed in the States (completely wrong and shameful I am afraid to say).

Click on the following link to read lots more: CAT PAWS.

Cat anatomy - The impressive cat tongue

Cat anatomy - The impressive cat tongue with the velcro (photographer's term, which I like) like surface of spines facing backwards. Photo above by Figuromo This photo won a prize in the Digital Camera Magazine Photographer of The Year competition. It is published here under a creative commons license.

Cat Tongue

A cat's tongue (see above) is an essential piece of cat anatomy. When you see a cat scoop up water from a cup with her/his tongue it is impressive. It is an essential grooming tool as well.

Read and see lots more by clicking on the following link: CAT'S TONGUE.

Cat anatomy - Cat eyes - photo by parl (Flickr)

Cat anatomy - Cat eye showing slit aperture
photo by EnKayTee

Eyes

Cat eyes are less good than ours in respect of color reception, it is thought. But it is known that a cat's eyes are much better for seeing in the dark. This is due to a reflective layer at the back of the eye which reflects light back onto the retina magnifying the reception. They also have that slit of an aperture for a reason.  The special science behind cat eyes has been utilized in helping whales. See feline eye disease. The cat eye is adapted for crepuscular (dusk and dawn) hunting.

Click on the following link to read and see more: CAT EYES.

Cat Ears

A cat's ears are very mobile. The outer ear (the bit you see) called the eat flap or more technically Pinna (the two flaps are called Pinnae) can swivel to pick up sound more effectively than humans.

The ear is very expressive as a result as they are a means of communication. There are folds in the ear flap called Henry's Pocket. I speculate that this oddity of anatomy is a way of enhancing hearing.

Cat anatomy - Pronounced cat ears on these kittens in Burma
Photo by phitar

There are apparently 5 basic ear signals.

• relaxed....ears point forward and slightly outward (subject to cat breeding as some breeds have rather extreme appearances). The cat listens. 
• alert mode....ears point to source of sound, which will be ahead as cat faces source of interest. Ears may swivel to side for short time if another sound occurs. 
• agitated mode....ears twitch nervously. If the cat has ear tufts (Maine Coon cats have ear tufts to name one breed - you'll see some great tufts on the linked page) this twitching is more noticeable. 
• defensive mode....ears become flattened for protection. This doesn't apply to the Scottish Fold!! 
• aggressive mode....ears are rotated to show the back of the ear ready to be flattened. This is a signal to beware to other animals. In the wild cat and in some wild cat hybrids you'll see markings on the back of the ear to reinforce this signal. See the Serval for example.

Cat anatomy - Feral cat trimmed ear (see left ear)
photo by ♥ he@rt ♥

Feral cat ears become damaged in fights despite the flattening of the ear and humans nip a piece of the ear of a feral cat when the cat has been spayed/neutered and returned (TNR). Click on the link to see damaged car ears. Cat ears can suffer infestation with mites and parasites, which should be watched for (click the link for a post on cat ear mites). My cats have never suffered this condition, however. I would have thought that it is more likely to occur in feral cats and neglected cats living in neglected human surroundings. There may be a natural cure for cats ear infection. I made an earlier post about cat anatomy focusing on the ears, which might be of interest. Read lots more by clicking on the following link: CAT'S EARS.

Cat anatomy - cat nose - photo by red_a_27

Cat's Nose  A cat's sense of smell is 14 times better than a human's sense of smell because the organ sensing odor particles is larger. If one watches cats it is apparent that the cat will rely on her/his heightened sense of smell very frequently. Smell is much more an integral part of a cat's life than for us. A cat's world is often centered around her sense of smell.  A cat decides what to eat by how attractive the food smells. A cat checks out whether there have been other animals and cats in their territory by his/her sense of smell. She will leave her odor on you by head butting and rubbing up against you to create a friendly smelling environment for herself and as a greeting. Head butting is a friendly exchange of body odors. A male cat will smell a female cat on heat. (see cats mating). A cat establishes territory by depositing urine and pheromones (from glands in the cats feet and facial area). These are readily picked up by other cats' acute sense of smell. The age of the smell will tell the cat smelling the odor if the territory is still occupied. Male cat spraying is a useful form of communication. In addition to the usual sensory receptors in the nose the cat has another organ that gives a boost to her sense of smell. You can see a cat use this organ because she/he will open her mouth slightly (a little like an odd smile) and breath in to suck in air to pass over the organ, which is inside the mouth. It is called Jacobson's Organ (scientific name is vomeronasal organ). The bit of nose we see, the nose leather is quite tough to allow it to absorb rather rough treatment sometimes. The color varies according to the genotype (genetic makeup) of the cat. Cat's skin has the same color as the fur but the color of the nose leather is probably dictated by a dedicated gene. Cats with white fur have skin susceptible to damage by ultra violet light that may cause cancer. Extra care is required when she/he goes outside in hot sun. Some people think a dry cat nose signifies and illness or is an illness. Read about Cat Dry Nose Illness. Click on the link to read lots more: CAT'S NOSE. Cat Fur Cat fur is cat anatomy that is the most obvious to cat keepers. Combined with the cat's head shape and body conformation it is the most important aspect of cat for the cat breeder. The color of cat fur and the patterns are governed by genes that are well known to cat breeders. Some cats have single coats, some double or treble coats. See CAT HAIR for more on this. The most commonly encountered cat coat is the tabby cat coat. Another common and well loved coat is the tortoiseshell and white or Calico as this color/pattern combination is called in the USA. I have made a series on posts on a range of cat coat types. Click on the links to see them:

Cat Anatomy - Plenty of cat fur
photo by champagne.chic

Cat Coats Black | Tabby | Solid and White | Black Tortoiseshell | Torbie | Dilution | Tuxedo | Tabby and White | Torbie/Tortie and White | Pointed | Pointed and White | White | Hairless | Curly | Glitter | Calico Cats | A cat's fur coat is most commonly a double coat. There is a top coat made up of guard hairs and an undercoat made up of fine downy hair. It is this hair that mats. Hair loss in cats can be a health issue. Some cats only have one coat. The Turkish Angora is a cat with no undercoat. Fur is a nice home for some parasites - see some cat and dog parasite pictures. A regular inspection of your cat for fleas and parasites generally is pretty essential. It is easy to let this drift and forget about it. Cats get fleas easily. They will need treatment either mechanically (combing) or chemical (drops). I would be cautious with chemical treatments as they can affect a cat adversely. Cat whiskers are many times longer and stiffer than cat fur. They are called vibrissae. They serve a purpose well beyond the measurement of the size of a gap. The area around the base of the whiskers contains highly sensitive nerve cells that transmit information back to the brain. They are so sensitive that they can detect small changes in air currents. Click on the link to read about CAT WHISKERS.

Cat Anatomy - Photo by Curious Expedition

This picture was taken at Wax Anatomical Models at La Specola in Florence, Italy. Other cat anatomy subjects:

• CAT GENETICS
• CAT'S TAIL
• CAT SOUNDS
• CAT TEMPERATURE

Sources:

• http://www.pets.ca/
• http://www.felinefuture.com
• Catwatching - Desmond Morris
• http://cats.about.com