This family is represented by 14 genera and 34 species. Canids are widely distributed, occurring on all continents except Antarctica. It is the only member of the Order Carnivora that it represented in Australia ( Canis familiaris dingo, the dingo; this species is thought to have been introduced by humans during prehistoric times). Fossil records of the Canidae date back to the Oligocene and the Miocene, making them one of the oldest extant groups of carnivores. Canids are probably an early offshoot of the caniform lineage (which includes mustelids, procyonids, ursids, phocids, otariids, and odobenids).
Primarily medium-sized flesh eaters, canids are more omnivorous than many carnivores, taking as food 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 for 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 and a long muzzle.
The legs and feet of canids are moderately elongated, and their stance is digitigrade. Usually, five toes are found on the forefeet and four on the hindfeet (one genus, Lycaon, has only 4 toes on the forefeet). The metapodials are long but not fused. Unlike the Felidae, 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. All male canids have a well-developed baculum.
Canids have nearly a full set of teeth with the following dental formula: 3/3, 1/1, 4/4, 1-2/2-3 = 38-42 (members of the genus Otocyon sometimes have additional molars). Canine teeth are large but unspecialized. Molars are of the crushing type. The carnassial pair is strongly built.
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. In wolves, mating occurs only between the two dominant individuals in the pack. 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.
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.
Literature and references cited
Feldhamer, G. A., L. C. Drickamer, S. H. Vessey, and J. F. Merritt. 1999. Mammalogy. Adaptation, Diversity, and Ecology. WCB McGraw-Hill, Boston. xii+563pp.
Paradiso, J. L. 1975. Walker's Mammals of the World, Third Edition. Johns Hopkins University Press, Baltimore.
Savage, R. J. G. and M. R. Long. 1986. Mammal Evolution, an Illustrated Guide. Facts of File Publications, New York. 259 pp.
Stains, H. J. 1984. Carnivores. Pp. 491-521 in Anderson, S. and J. K. Jones, Jr. (eds). Orders and Families of Recent Mammals of the World. John Wiley and Sons, N.Y. xii+686 pp.
Vaughan, T. A. 1986. Mammalogy. Third Edition. Saunders College Publishing, Fort Worth. vii+576 pp.
Vaughan, T. A., J. M. Ryan, N. J. Czaplewski. 2000. Mammalogy. Fourth Edition. Saunders College Publishing, Philadelphia. vii+565pp.
Wilson, D. E., and D. M. Reeder. 1993. Mammal Species of the World, A Taxonomic and Geographic Reference. 2nd edition. Smithsonian Institution Press, Washington. xviii+1206 pp.
Bridget Fahey (author), University of Michigan-Ann Arbor, Phil Myers (author), Museum of Zoology, University of Michigan-Ann Arbor.
- bilateral symmetry
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
having the capacity to move from one place to another.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate