Canidae familyPosted: Updated:
Taxonomy is the science of classifying organisms, and the process breaks them down into seven major divisions, called taxa (singular: taxon). This organizational method tells us something about the relationship of different organisms and paints a vivid picture of the earth's diversity through time.
In order to classify an organism into a particular level, scientists look at similarities of form and function. Within the Canidae family, there are 36 living species which are subdivided into three subfamilies: Hesperocyoninae, Borophaginae, and the Caninae lineage that led to present-day canids, including wolves, foxes, coyotes, jackals, and domestic dogs. They are found on every continent except Antarctica, and inhabit a wide range of different habitats, including deserts, mountains, forests, and grassland. They vary in size from the Fennec Fox at 10 inches in length to the Gray Wolf which may be up to 6.5 feet long and can weigh up to 175 pounds. Primarily medium-sized flesh eaters, canids are more omnivorous than many carnivores, consuming invertebrates, plant matter, and carrion as well as the prey they kill themselves. They are adapted more for endurance than for speed, and they catch prey by pursuit over long distances in relatively open terrain until the prey tires.
Kills are made by grabbing from the nape of neck and tackling the prey to the ground. The neck grab is followed by a violent shake, which may dislocate the neck of the prey. Large prey may be immobilized by biting into the soft parts of the underbelly, often resulting in disembowelment and death from shock. Sense of smell is acute and appears to be critical to these animals, as is hearing, but sight is less developed.
Canids have deep-chested bodies, a long muzzle, and bushy tails. The legs and feet are moderately elongated, and their stance is digitigrade (they walk on their toes). Usually, five toes are found on the forefeet and four on the hindfeet and, unlike the Felidae (cat family), canids have non-retractile claws. This means that they are worn down by activity and are not the specialized weapons found in some other carnivores.
Canine teeth are large but unspecialized. Canids have nearly a full set of teeth and the molar teeth are strong in most species allowing the animals to crack open bone to reach the marrow.
Some species (generally ones with larger body sizes) form packs with strict social hierarchies and mating systems. Hunting in packs allows canids to capture species much larger than themselves. Pack-forming species, as well as less gregarious species such as foxes, are very territorial. Territory marking occurs in many species through repeated urination on objects on the periphery and within territories. Other scent glands are also important in the social behavior of these species; these include anal glands and glands on the dorsal surface of the tail near the base.
The Canidae family evolved over about 40 million years. Each subfamily showed an increase in body mass with time before their specialized hypercarnivorous diet made some prone to extinction. These early canids probably evolved for fast pursuit of prey in a grassland habitat, and resembled modern civets in appearance. Continued success was attributed in part to the development of lower carnassials (molars) that are capable of both mastication and shearing.
Many species are viewed as pests to humans, and populations of many species have been decimated. Coyotes and wolves are both persecuted by ranchers, who blame them for losses to sheep and cattle herds. Other species have been targeted as carriers of rabies (many of the foxes) and likewise have been the target of hunting. Some foxes are valued for their pelts, which have been used in the fashion industry. The domestic dog ( C. lupus familiaris) has been domesticated for thousand of years and has been useful to humans in many ways, such as transport, guarding of livestock, and protection, although many are used primarily for companionship.
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