The mammals are the class of vertebrate animals characterized by the production of milk in females for the nourishment of young, from mammary glands present on most species and specialized skin glands in monotremes that seep or ooze milk; the presence of hair or fur; specialized teeth; three minute bones within the ear; the presence of a neocortex region in the brain; and endothermic or "warm-blooded" bodies.

The brain regulates endothermic and circulatory systems, including a four-chambered heart.

Mammals encompass some 5,500 species (including humans), distributed in about 1,200 genera, 152 families and up to 46 orders, though this varies with the classification scheme.

Most mammals give birth to live young, but a few (the monotremes) lay eggs.

Live birth also occurs in some non-mammalian species, such as guppies and hammerhead sharks; thus it is not a distinguishing characteristic of mammals..

For more information about the topic Mammal, read the full article at Wikipedia.org, or see the following related articles:

Vertebrate — Vertebrates are members of the subphylum Vertebrata (within the phylum Chordata), specifically, those chordates with backbones or spinal columns. ...  > read more

Marsupial — Marsupials are mammals in which the female typically has a pouch in which it rears its young through early infancy. They differ from placental ...  > read more

Caribbean Monk Seal — The Caribbean Monk Seal, the only seal ever known to be native to the Caribbean sea and the Gulf of Mexico, is now considered ...  > read more

Amphibian — Amphibians generally spend part of their time on land, but they do not have the adaptations to an entirely terrestrial existence found in most other ...  > read more

Related Stories

Loss Of Egg Yolk Genes In Mammals And The Origin Of Lactation And Placentation (March 19, 2008) — The major egg yolk genes, those that express vitellogenins, appear to have progressively lost their functionality during mammalian evolution, probably due to the emergence of the mammalian-specific ...  > read more

Prehistoric Jawbone Reveals Evolution Repeating Itself (February 16, 2005) — A 115-million-year-old fossil of a tiny egg-laying mammal thought to be related to the platypus provides compelling evidence of multiple origins of acute hearing in humans and other ...  > read more

Study On Papua New Guinea's Long-beaked Echidna Reveals Elusive Habits (June 23, 2009) — A research intern working in the wilds of Papua New Guinea has successfully completed what many other field biologists considered "mission impossible" -- the first study of a rare egg-laying mammal ...  > read more

Mirror Self-recognition In Magpie Birds (August 19, 2008) — Self-recognition, it has been argued, is a hallmark of advanced cognitive abilities in animals. It was previously thought that only the usual suspects of higher cognition -- some great apes, dolphins ...  > read more

New Mesozoic Mammal: Discovery Illuminates Mammalian Ear Evolution While Dinosaurs Ruled (October 9, 2009) — An international team of paleontologists has discovered a new species of mammal that lived in China's Liaoning Province 123 million years ago. This remarkably well preserved fossil offers important ...  > read more

Search ScienceDaily

Name That Species