Teat is an alternative word for the nipple of a mammary gland, in humans referred to as a breast, from which milk is discharged. Similarly in cows, goats, etc., it is the projection from the udder through which milk is discharged.
The rubber mouthpiece of a baby's feeding bottle and dummy, and similar items, are referred to as a teat.
The word "teat" is of Germanic origin, having the same origin as the Dutch word "tiet" and German "Zitze". In turn, this word has Indo-European roots, as may be seen in the Welsh word "teth". The Old English for teat was "tit", which is still used as a vulgar or slang term in Modern English.
The number of teats varies in Mammals from 2 to 19 . Marsupials and Eutherian mammals have teats from which their young suckle milk. Monotremes lack teats; their young drink milk directly from pores in the skin (similar to sweat glands), or by sucking it off of hairs surrounding the pores. In most Eutherian mammals, both males and females have teats. Those of the male are nonfunctional except in cases of hormonal imbalance. Notable exceptions to this are the male rat and the male horse, neither of which has teats.
Teats vary in size, location, and structure in different mammalian species. Female goats and ewes have two teats, each with a single mammary gland, located between the hindlegs. Mares have two teats, each with two mammary glands. The teats of the sow can be quite variable in number, from six to thirty, and are located on two parallel lines along the belly. Cows have four teats, each with one mammary gland in the udder. Extra teats occur often, and are known as supernumerary teats. They are nonfunctional and are usually removed from domestic animals.
The offspring of domestic animals, including piglets, calves, lambs, and foals, engage in a behavior known as teat seeking. This strong instinct occurs in most species within minutes of birth, and serves both to connect the young to the food source and to encourage bonding between mother and young.
This article is based on "Teat" from the free encyclopedia Wikipedia (http://en.wikipedia.org). It is licensed under the terms of the GNU Free Documentation Licencse. In the Wikipedia you can find a list of the authors by visiting the following address: http://en.wikipedia.org/w/index.php?title=Teat&action=history