Dog Wallpapers

Dog Animals - photo wallpapers; Megawallpapers.org: This article discusses the domestic dog. For other members of the dog family, see Canidae. [br]The dog is a canine omnivorous mammal that has been domesticated for somewhere between 14,000 and 150,000 years. In this time, the dog has developed into hundreds of breeds with a great degree of variation. For example, heights ranging from just a few inches (such as the Chihuahua) to nearly three feet (such as the Irish Wolfhound), and colors ranging from white to black with reds, grays, and browns also occurring in a tremendous variation of patterns. The dog is known for its trainability, its playfulness, and for its ability to fit into human households and social situations. See dog training for details. In some countries dogs are most often kept as pets, although a wide range of dog sports provides opportunities for dogs to exhibit their natural skills, and working dogs of all kinds still fill traditional dog roles such as herding sheep and cattle while moving into new jobs such as detecting contraband. They have lived with and worked with humans in so many roles that they have earned the sobriquet Man's best friend. Terminology for dogs: Dog, in common usage, refers to the domestic dog, Canis lupus familiaris (originally classified as Canis familiaris by Linnaeus in 1758, but reclassified as a subspecies of the wolf, Canis lupus, by the Smithsonian Institution and the American Society of Mammalogists in 1993). The word is sometimes used to refer collectively to any mammal belonging to the family Canidae (as in "the dog family"), such as wolves, foxes and coyotes. Dog is also a term used by breeders to specifically denote a male domestic dog. The female is known as a bitch. A young dog is called a puppy. The words pooch and poochie are generic, generally affectionate terms for a dog. Many additional terms are used for dogs that are not purebred; see Terms for mixed-breed dogs. Attributes: Modern dog breeds show more variation in size, appearance, and behavior than any other domestic animal. Within the range of extremes, dogs generally share attributes with their wild ancestors, the wolves. Dogs are predators and scavengers, possessing sharp teeth and strong jaws for attacking, holding, and tearing their food. Their legs are designed to propel them forward rapidly, leaping as necessary, to chase and overcome prey. Consequently, they have small, tight feet, walking on their front toes; their rear legs are fairly rigid and sturdy; the front legs are loose and flexible, with only muscle attaching them to the torso. Dogs are believed to be red-green colorblind and, because the lenses of their eyes are flatter than humans', they cannot see as much detail; on the other hand, their eyes are more sensitive to light and motion than humans' eyes. Some breeds have a field of vision up to 280� (compared to 180� for humans), although broad-headed breeds with their eyes set forward have a much narrower field of vision than, for example, sight hounds. They detect sounds in the 70-100,000 Hz frequency range (compared to 16-20,000 Hz for humans), and in addition have a degree of ear mobility that helps them to rapidly pinpoint the exact location of a sound. Dogs have about 220 million smell-sensitive cells (compared to 5 million for humans). Some breeds have been selectively bred for excellence in detecting scents, even compared to their canine brethren. All dogs have a tremendous capacity to learn complex social behavior and to interpret varied body language and sounds, and, like many predators, can react to and learn from novel situations. Dog coats, colors, and markings: Dogs exhibit a diverse array of coat textures, colors, and markings, and a specialized vocabulary has evolved to describe them. Originally, dogs all had dense fur with an undercoat and long muzzles and heads, although both of these features have been altered in some of the more extremely modified breeds, such as the Mexican Hairless and the English Bulldog. [br]One often refers to a specific dog first by coat color rather than by breed; for example, "a blue merle Aussie" or "a chocolate Lab". Coat colors include: Blenheim: A combination of chestnut and white; for example, the Cavalier King Charles Spaniel. Black: Usually pure black but sometimes grizzled, particularly as dogs age and develop white hairs, usually around the muzzle. Black and tan: Coat has both colors but in clearly defined and separated areas; usually the top and sides are black and lower legs and underside are tan, reddish, or chestnut. Blue: A dark metallic gray, often as a blue merle or speckled (with black). Kerry Blue Terriers, Australian Silky Terriers, Bearded Collies, and Australian Shepherds are among many breeds that come in blue. Brown: Includes dark mahogany, midtone brown, gray-brown, and very dark brown. Cream: Depending on the breed and individual, ranges from white through ivory and blond, often occurring with or beneath lemon, yellow, and sable. Gold: Rich reddish-yellow, as in a Golden Retriever; often includes colors such as yellow-gold, lion-colored, fawn, apricot, wheaten, tawny, yellow-red, straw, mustard, and sandy. Gray: Pale to dark gray, including silver; can be mixed with other colors or various shades to create sandy pepper, pepper, grizzle, blue-black gray, or silver-fawn. Lemon: A very pale yellow or wheaten colour which is not present at birth (the puppies are born white) but gradually becomes apparent, usually during the first six months of life. Liver: A reddish brown somewhat the color of cinnamon or bronze; the breed often determines whether "liver", "chocolate", "brown", or "red" is used to describe the color, as in a liver German Shorthaired Pointer or a chocolate Labrador Retriever. [br]Red: Reminiscent of reddish woods such as cherry or mahogany; also tawny, chestnut, orange, rusty, and red-gold. [br]Sable: Black-tipped hairs; the background color can be gold, silver, gray, or tan. Tricolor: Consisting of three colors; usually black, tan, and white or liver, tan, and white; for example, the Smooth Collie or the Sheltie. Wheaten: Pale yellow or fawn, like the color of ripe wheat. White: Distinct from albino dogs. Yellow: Yellowish-gold tan, as in a yellow Labrador Retriever. Coat patterns include: Brindle: A mixture of black with brown, tan, or gold; usually in a "tiger stripe" pattern. Harlequin: "Torn" patches of black on white; only the Great Dane exhibits this pattern. Merle: Marbled coat with darker patches and spots of the specified color; for example, a blue merle is marbled gray and blue with black and sometimes white patches; a red (or liver) merle has deep red or brown on lighter red, often with white or black mixed in. [br]Particolor: Two-colored coat with the colors appearing in patches in roughly equal quanties (in breeds where this is an allowed coat color; in breeds where patches of white are considered undesirable, a dog showing even a small patch of white might be classified as a particolour). Coat textures vary tremendously, so that some coats make the dogs more cuddly and others make them impervious to cold water. Densely furred breeds such as most sled dogs and Spitz types can have up to 600 hairs per inch, while fine-haired breeds such as the Yorkshire Terrier can have as few as 100, and the "hairless" breeds such as the Mexican Hairless have none on parts of their bodies. The texture of the coat often depends on the distribution and the length of the two parts of a dog's coat, its thick, warm undercoat (or down) and its, rougher somewhat weather-resistent outer coat (topcoat), also referred to as guard hairs. Breeds with soft coats often have more or longer undercoat hairs than guard hairs; rough-textured coats often have more or longer guard hairs. Textures include: Double-coated: Having a thick, warm, short undercoat (or down) that is usually dense enough to resist penetration by water and a stronger, rougher weather-resistent outer coat (topcoat), also referred to as guard hairs. Most other coat types are also double coated. Single-coated: Lacking an undercoat. Smooth-coated: "Smooth" to the eye and touch. Wire-haired: Also called broken-coated. The harsh outer guard hairs are prominent, providing excellent weather protection for hunting dogs such as the Border Terrier or Wirehaired Pointing Griffon. Long-haired: Hair longer than an inch or so. Short-haired: Hair around an inch or so long. Corded coat: for example, see Puli. Ancestry and history of domestication: This ancient mosaic shows a large dog with a collar hunting a lion.Molecular systematics indicate that the domestic dog is descended from a wolf-like ancestor, and dogs and wolves can still interbreed. The domestication of the dog probably occurred at least 14,000 years ago, and perhaps long before that. There is archaeological evidence of dog remains, showing the characteristic morphological differences from wolves, from at least 14,000 years ago, while wolf remains have been found in association with hominid remains that are at least 400,000 years old. The molecular genetic data suggest that the domestic lineage separated from modern wolves around 150,000 years ago (Vil� et al, 1997). In the early 2000s, some research (http://www.amonline.net.au/archive.cfm?id=716) indicated that domestication in fact had already begun to occur as early as 100,000 years ago.n Dogs were, and are, valued for their aid in hunting. Dog burials at the Mesolithic cemetery of Svaerdborg in Denmark indicate that in ancient Europe, dogs were valued companions. Some evidence suggests that several varieties of ancient wolves contributed to the domestic dog, with deliberate or unintentional interbreeding taking traits from one or more of the ancestral wolf lines. Although all wolves belong to the species Canis lupus, there are (or were) many subspecies that had evolved somewhat distinctive appearance, social structure, and other traits. For example, the Japanese wolf, which became extinct in the early 20th century, was much smaller than most wolves, generally had a gray coat with reddish underbelly, and possibly had a more solitary hunting habit; the North American wolf, which still exists in limited ranges, is much larger than many wolf subspecies, displays many coat colors from nearly white through solid black, and exhibits a complex social structure involving highly formulaic dominance and submission rituals. The Indian or Asian wolf probably led to the development of more breeds of dogs than other subspecies. Many of today's wild dogs, such as the dingo and pariah dogs, are descended from this wolf, along with sighthounds such as the Greyhound. Recent genetic evidence (http://www.abc.net.au/rn/science/ss/stories/s728909.htm) shows that most modern dog breeds are related to Asian canines, contradicting earlier hypothoses that the dog, like humans, had evolved originally in Africa. The Asian wolf also likely interbred with descendants of the European wolf to create the Mastiffs�the Tibetan Mastiff being an example of a very ancient breed�leading eventually to the development of such diverse breeds as the Pug, the Saint Bernard, and the Bloodhound. The European wolf, in turn, may have contributed many of its attributes to the Spitz dog types, most terriers, and many of today's sheepdogs. The Chinese wolf is a probably ancestor to the Pekingese and toy spaniels, although it is also probable that descendants of the Chinese and European wolves encountered each other over the millennia, contributing to many of the oriental toy breeds. The North American wolf is a direct ancestor to most, if not all, of the North American northern sled dog types; this mixing and crossing still goes on today with dogs living in the Arctic where the attributes of the wolf that enable it to survive in a hostile environment are still valued. Additionally, accidental crossbreeding occurs simply because dogs and wolves live in the same environment. Current research indicates that domestication, or the attributes of a domesticated animal, can occur much more quickly(http://www.amsci.org/amsci/articles/99articles/Trut.html#26879) than previously believed, even within a human generation or two with determined selective breeding. It is also now generally believed that initial domestication was not attained deliberately by human intervention but through natural selection: wild canines who scavenged around human habitation received more food than their more skittish counterparts; those who attacked people or their children were probably killed or driven away, while those more tolerant animals survived, and so on. [br]From Wikipedia, the free encyclopedia.

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