Cat - biology.

Cat - biology. I INTRODUCTION Cat, small, mainly carnivorous animal, Felis silvestris catus, member of the family Felidae, popular as a household pet, and valuable for killing mice and rats. Like other members of the cat family, the domestic cat has retractile claws; keen hearing and smell; remarkable night vision; and a compact, muscular, and highly supple body. Cats possess excellent memory and exhibit considerable aptitude for learning by observation and experience. The natural life span of a domestic cat is about 15 years. There are an estimated 600 million house cats in the world. II ORIGIN OF SPECIES Debate has surrounded the origin of the domestic cat. A common theory held that cats were first domesticated by ancient Egyptians perhaps as early as 2500 BC from the African or Near Eastern wildcat Felis silvestris libyca, also called the Caffre cat. Crusaders then transported the cat to Europe, where it interbred with the indigenous smaller wildcats Felis silvestris silvestris. The idea that domestic cats in different parts of the world had originated from, or interbred with, populations of local wildcats and other small cat species was proposed by a number of experts. For example, the longhaired breeds of domestic cats were said to come from the Asian Pallas's cat, Felis manul. However, a study published in 2007 compared the mitochondrial DNA of domestic cats and wildcats and concluded that the domestic cat derives only from Felis silvestris libyca. Members of this particular subspecies of wildcat were domesticated in the Middle East, likely around the time that farming villages first developed in the Fertile Crescent region between 10,000 and 12,000 years ago. Wildcats probably began associating with human settlements to prey on the rodents and other pests attracted by stored grains and cereals. Some of the wildcats then gave up their more aggressive wild behaviors to adapt to life with people. The DNA study indicates that at least five individual female cats from the Middle East served as founders for all the domestic cats that were later carried around the world by humans. This new DNA evidence appears to contradict theories that domestic cats carry genes that come from other types of small cats and from wildcats found in different parts of the world. Some interbreeding between domestic cats and local wildcats probably took place, however. Over the centuries, cats have remained virtually the same in size, weighing about 3.6 kg (about 8 lb) when full-grown, and have preserved their instinct for solitary hunting. III PHYSIOLOGY OF THE CAT The body of a domestic cat is extremely flexible; its skeleton contains more than 230 bones (the human skeleton, although much larger, contains 206 bones), and its pelvis and shoulders are more loosely attached to its spine than in most other quadrupeds. The cat's great leaping ability and speed are due in part to its powerful musculature. Its tail provides balance when jumping or falling. The cat's claws are designed for catching and holding prey. The sharp, hooked, retractile claws are sheathed in a soft, leathery pocket at the end of each toe, and are extended for fighting, hunting, and climbing. The cat marks its territory by scratching and scenting trees or other objects; its claws leave visible scratch marks, and the scent glands on its paw pads leave a scent mark. The cat's teeth are designed for biting, not for chewing. Its powerful jaw muscles and sharp teeth enable the cat to deliver a killing bite to its prey. A Senses The cat's vision is exceptionally well adapted for hunting, especially at night. It has excellent night vision; extensive peripheral vision; and binocular vision, which enables it to accurately judge distances. The cat's daylight vision is not as good as that of humans; cats see movement much more easily than detail, and are thought to see only a limited range of colors. The cat's hearing is extremely sensitive. It can hear a wide range of sounds, including those in the ultrasonic range. Its ears are less sensitive to lower frequencies, which may explain why some domestic cats are more responsive to female voices than to male voices. The cat can turn its ears to focus on different sounds. The cat has a highly developed sense of smell, which plays a vital role in finding food and in reproduction. Many of the social signals of domestic cats take the form of scents; for example, male cats can apparently smell a female cat that is receptive to male cats from a distance of hundreds of meters or yards. The cat's sense of taste is peculiarly specialized: It has little ability to detect sweetness, but is extremely sensitive to slight variations in the taste of water. The cat's tongue is covered with rough protuberances, or papillae, that it uses to rasp meat from bones. It also uses its tongue to groom itself. The cat's whiskers, or vibrissae, are extremely sensitive to the slightest touch, and are used for testing obstacles and sensing changes in the environment. In extremely dim light, a cat may feel its way by using its whiskers. B Vocal Sounds Cats make a distinctive set of vocal sounds. The meow call is typically made for humans, not for other adult cats. The meow can be low-pitched if the cat is agitated or high-pitched if the cat is happy or is welcoming a person. The meow can be a demand for food or for attention. Mother cats use a trilling kind of meow with their kittens. Male cats caterwaul when encountering other males and when preparing to mate with a female. Females sometimes yowl when they are in heat to attract males. Hisses, screams, or growls indicate a cat is frightened or feels threatened. Other cat sounds include chirps and chatters when looking for prey. Purring is thought to be produced by moving muscles in the voice box and in the diaphragm as the cat breathes in and out. Although cats often purr to show contentment, cats also purr when they are injured or in distress. Some research suggests the vibrations from purring may help heal injured bones. C Reproduction The domestic cat usually reaches puberty at around nine or ten months of age. A sexually mature female cat goes into heat, or estrus, several times a year; during estrus, she is both receptive to, and attractive to, male cats. The gestation period of the cat is about 65 days; the average litter consists of 4 kittens. Kittens are born blind, deaf, and helpless. Their eyes open at 8 to 10 days of age, and they begin to be weaned about 6 weeks after birth. D Coat Colors The domestic cat's original coat color was probably grayish-brown with darker tabby stripes, a color that provides excellent camouflage in a variety of environments. All other coat colors and patterns are the result of genetic mutations; for example, solid coat colors such as black and blue are the result of a gene that suppresses tabby stripes; an orange coat is the result of a gene that transforms black pigment to orange; and a solid white coat is the result of a gene that completely suppresses all formation of pigment. Two pigments, black and orange, form the basis for all coat colors in the modern domestic cat. These pigments may be combined with each other or with white (the absence of pigment). A single gene, the O (Orange) gene, determines whether a cat's coat contains black or orange pigment. The O gene can be thought of as a switch that is either on (orange) or off (black). The gene is located on the X chromosome, so its inheritance is sex-linked. IV CAT BREEDS About 40 varieties, or breeds, of domestic cats are recognized internationally. Although the various cat breeds often differ dramatically in coat length and overall look, they vary less in size than do dog breeds. The smallest cat breeds weigh about 2 to 3 kg (about 5 to 7 lb) when full-grown; the largest weigh about 7 to 9 kg (about 15 to 20 lb). So far, attempts to develop miniature or giant domestic cat breeds have been unsuccessful. A Breed Origins Many domestic cat breeds, including the Maine coon, Manx, Russian blue, and Siamese, began as a naturally occurring variety of domestic cat native to a specific geographic area. Others, such as the Himalayan, are artificially created breeds, the result of generations of careful breeding for a desired look. Some relatively new breeds, including the curly-coated Rex breeds, the hairless Sphynx, the fold-eared Scottish fold, and the curl-eared American curl, began with a genetic mutation and were then developed by selective breeding into a distinct breed. B Breed Standards For each domestic cat breed, there is an official standard of perfection registered with different cat associations that describes the ideal cat of that breed and its distinctive features; lists desirable and undesirable characteristics; and mentions faults that, in a cat show, could result in penalty or disqualification. For example, in the Siamese breed standard, the eyes are described as almond-shaped and slanting toward the nose; a tendency to squint is penalized, and crossed eyes are a disqualifying fault. Breed standards differ slightly from cat association to cat association, and not all cat associations recognize every breed. To become recognized in a particular cat association, a breed must first be accepted for provisional status by that association. To become recognized for championship competition, the breed must complete a rigorous set of requirements that differ from association to association. V THE CARE OF CATS Cats are known for their ability to fend for themselves in the wild, but household pets, dependent on human beings for care and feeding, require considerable attention. Educational materials on the care of cats and responsible cat ownership are available through bookstores and local humane societies. A General Care Although cats have a reputation for being relatively independent, domestic cats require love and attention from their owners. A balanced daily diet, such as that provided by high-quality commercial cat food, is essential for health and longevity, as is a regular supply of fresh water. Regular cleaning of litter pans is necessary to prevent disease; some cats will refuse to use a badly soiled litter pan. Cats' claws should be trimmed frequently. To prevent damage to furniture, cats that live indoors should be provided with a scratching post, preferably covered with a rough material such as sisal rope. Cats use their tongues to clean their coats, and they normally swallow any loose hair. All cats, including shorthairs, should be brushed weekly to remove loose hair; this will help prevent hairballs from forming in their stomachs. A few longhaired breeds, such as the Persian and the Himalayan, require daily combing to prevent their long, soft fur from matting. B Neutering or Spaying Every year hundreds of thousands of unwanted domestic cats and kittens are destroyed because homes cannot be found for them. To avoid contributing to this problem, a cat should be altered (surgically treated to make it incapable of reproducing) unless it is a registered, pedigreed member of a responsible breeding program. A female cat is spayed (altered by removing the uterus and ovaries); a male cat is neutered (altered by removing the testicles). Cats that have been altered are healthier and easier to live with. Unaltered females may be susceptible to uterine infections and ovarian cysts; unaltered cats of both sexes may mark their territory by spraying urine. Some veterinarians recommend altering cats as young as 12 weeks of age, while others recommend waiting until the animal reaches sexual maturity (at six to ten months of age). Current veterinary research indicates that early altering has little negative effect on a cat's health; a low-quality diet, however, can cause serious urinary tract problems. C Indoors vs. Outdoors Some domestic cat owners choose to keep their cats indoors; others permit their cats to go outdoors some or all of the time. The decision of whether to allow a cat outdoors is a personal one; cats that have been declawed, however, and those that have not been altered, should not be allowed outdoors unless confined to a covered enclosure. Cats that are allowed outside have some degree of freedom and independence, and may enjoy hunting small animals and interacting with other cats; they get plenty of exercise and are unlikely to become bored or lonely. The outdoors, however, poses many hazards to cats, even in rural areas. An outdoor cat may be struck by a car, poisoned by common pesticides, or injured by other animals (other cats, dogs, and, in some areas, wild animals such as coyotes). In addition, the cat may be exposed to the fatal feline diseases that are endemic in the stray cat population. According to some authorities, a cat that is permitted outdoors has an average life expectancy of 3 to 5 years; conversely, the average life expectancy of an indoor cat is about 15 years. Although an indoor cat does not enjoy the same freedom as an outdoor cat, many indoor cats live happy and complete lives. It is easier to keep a cat indoors if it has not become accustomed to going out. Indoor cats need exercise just as outdoor cats do. Some cats can be trained to use a harness leash. Often, the easiest way to provide an indoor cat with exercise and stimulation is to provide a feline companion. D Cat Diseases Domestic cats are susceptible to a variety of viral and bacterial diseases. Fortunately, many common feline diseases can be controlled by a regular system of inoculation. Cats may also suffer from external parasites such as fleas and mites, and from intestinal parasites (worms). Cats can contract rabies from infected prey or other infected animals, but such instances are rare. Upper respiratory infections are a common feline illness and can sometimes be fatal, especially in young kittens. Vaccines provide some protection against the following upper respiratory diseases: feline viral rhinotracheitis (FVR), feline calicivirus (FCV), and chlamydia (feline pneumonitis). Panleukopenia (feline infectious enteritis) is a highly contagious, often fatal disease characterized by a sudden onset and severe gastrointestinal symptoms such as vomiting and diarrhea. Vaccination is the only effective way to control the disease. Feline leukemia virus (FeLV) is a fatal, contagious disease that is spread by direct contact. A cat with feline leukemia may have a variety of symptoms, including general malaise, weight loss, anemia, and fever. An infected cat may transmit the disease to other cats before it develops clinical symptoms itself. A blood test can detect whether a cat has been infected. Although a vaccine is available, the most reliable way to prevent a cat from contracting feline leukemia is to keep it from coming into contact with FeLV-positive cats. Feline infectious peritonitis (FIP) is an inflammation of the peritoneum (lining of the abdomen). Although FIP is contagious, some cats appear to develop a natural immunity to it. An infected cat may be a symptomless carrier. Once a cat develops symptoms, the disease is invariably fatal. There is no reliable blood test for FIP, but a vaccine is now available. E Inoculations Cats can be successfully inoculated against many serious feline diseases. Kittens should be inoculated against rhinotracheitis, calicivirus, panleukopenia, and, optionally, chlamydia. Most veterinarians recommend a series of two or three inoculations, given every 3 weeks starting at 6 weeks of age. After 12 weeks of age, a kitten may also be inoculated against rabies, feline leukemia, and feline infectious peritonitis. Inoculations should be repeated annually to maintain immunity. F Allergies to Cats Allergies to cats are among the most common allergic reactions in humans. A protein in the cat's skin and saliva causes the reaction, leading to itching, sneezing, and other allergy symptoms in people sensitive to the protein. For allergic people who wish to have a cat, allergists recommend keeping the cat out of the bedroom; bathing the cat, if the cat tolerates washing; using air purifiers to remove allergens; and, in some cases, receiving injections to desensitize the body against the allergen. In 2006 researchers at Allerca, a biotechnology company in San Diego, California, announced that they had produced a hypoallergenic (nonallergy producing) cat. The researchers found that some cats had a mutant gene that produced a protein far less likely to cause an allergic reaction. They bred these cats to create the hypoallergenic kittens. VI SHOWING AND JUDGING CATS Many owners, even those of mixed-breed cats, enjoy exhibiting their cats at shows. Judges at cat shows must be trained and certified. Purebred cats are judged on health, temperament, and how well they fit the official standard for their breed. Mixed-breed cats are judged on health, temperament, and general appearance. All cats are expected to be amenable to handling; a cat may be disqualified if it bites or otherwise injures a judge. A Cat Associations A cat association is an organization that registers cats and kittens, selects cat show judges, and schedules cat shows. There are various cat associations in the United States, including the Cat Fanciers' Association (CFA), The International Cat Association (TICA), and the American Cat Fanciers Association (ACFA). The largest of these groups, the CFA, registers more than 80,000 cats and kittens annually. All of the cat associations operate independently; cat clubs, breeders, and exhibitors choose which associations they wish to join and whose breed standards and rules they wish to follow. B Cat Shows An increasing number of local, regional, and national cat shows are held throughout the year in the United States, with hundreds of cats competing for awards. Owners show their cats for fun and to gain a reputation among other exhibitors and breeders. Cat shows typically do not award monetary prizes, and the entry fees and travel expenses can be expensive. Although exact show rules and procedures vary from association to association, the general format is the same. There are four categories of competition: purebred kittens, purebred adults, purebred alters (cats that have been neutered or spayed), and household pets (mixed-breed cats or kittens). A single cat show may have as many as 20 or more different judges; usually, a cat is judged by every judge in the show. At cat shows in the United States, each judge has his or her own ring--an area consisting of 10 to 15 numbered cages and a judging table. Cats wait in cages in another area of the show hall, called the benching area. The owners bring the cats to the ring when called and place them in the judging cages. The judge takes each cat out of its cage in turn, places it on the judging table, and examines the cat carefully to make sure that it is healthy and meets the standard for that breed. After judging each cat within a particular class or breed, the judge gives out preliminary awards, such as Best of Color or Best of Breed. After judging all the cats in a category, the judge gives top awards to the ten best cats in that category. Each judge works independently, and judges' opinions sometimes differ markedly. VII CAT LORE Cats and humans have interacted for thousands of years. These animals have figured in the history of many nations, are the subject of much superstition and legend, and are a favorite subject of artists and writers. A History and Legend The earliest archaeological record of cats and people together comes from a 9,500-year-old grave discovered in a Neolithic village on the island of Cyprus. A human was found buried with a cat, along with seashells and other decorations. Even older Neolithic engravings and pottery depict cats, indicating the animals may have had some religious significance. The ancient Egyptians may have been breeding tame cats over 4,000 years ago. Cats became objects of worship in ancient Egypt because of their ability to keep down the rodent population in the country's economically important grain fields along the Nile. The Egyptian cat goddess Bast, or Bastet, became associated with fertility and childbearing. Egyptian cats were also used for sport by their owners. Attached to leashes, these animals hunted birds for the family table; a boomerang flung by the master brought the birds down and the cats, unleashed, would retrieve them. Because they were economically useful and were believed to ensure many children for a family, cats were so revered that they were mummified and buried either with their owners or in specially designated cemeteries. Despite Egyptian laws that forbade the removal of the sacred cats, Phoenician sailors smuggled them out of the country. Cats were traded along with other treasures from the Middle East and in antiquity could be found throughout the Mediterranean area. Archaeological evidence indicates that the Romans were the first to bring cats to the British Isles. Throughout much of the Middle Ages, cats were feared and hated. Because of their nocturnal habits, they were believed to consort with the devil. This association with witchcraft has been responsible for many acts of cruelty toward cats through the centuries. The Renaissance, in contrast, was the golden age for cats. Almost everyone owned one, from members of royal families and their staffs down to the peasantry. The first domestic cats in North America arrived with the colonists and were employed to keep the rodent population under control in the settlers' fields, barns, and homes. Cats are said to have played an important part in keeping rats out of the California gold mines. In India cats often played an important part in religious or occult ceremonies. In South America the Inca revered sacred cats; cats are represented in pre-Columbian Peruvian artifacts. Cats continue to be worshiped as deities in countries such as Thailand and China. B Cats in Art and Literature Egyptian tomb paintings and sculpture are among the earliest representations of the domestic cat. Images of cats appear on Greek coins of the 5th century BC; cats were later depicted in Roman mosaics and paintings and on earthenware, coins, and shields. The 8th-century Irish manuscript of the Gospels, the Book of Kells, has a representation of cats and kittens in one of its illuminations. Later artists, such as the Italian artist Leonardo da Vinci and his German contemporary Albrecht Dürer, are among the many who included cats in their works. Although the Old Testament makes no mention of cats, the Babylonian Talmud tells of their admirable qualities and encourages the breeding of cats "to help keep the houses clean." Memorable literary cats include the British writer Rudyard Kipling's "Cat That Walked by Himself" (one of the Just So Stories, 1902), the delightful cats of Old Possum's Book of Practical Cats (1939) by the Anglo-American poet T. S. Eliot, and the Cheshire Cat, joint creation of the English writer Lewis Carroll and the illustrator Sir John Tenniel in the children's classic Alice's Adventures in Wonderland (1865). Andrew Lloyd Webber's long-running musical Cats (1981) was based on Eliot's poems. Many contemporary comic strips and animated cartoons also contain feline characters that delight ailurophiles (lovers of cats) of all ages. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.