Portal:Mammals

The Mammals portal

A mammal (from Latin mamma 'breast') is a vertebrate animal of the class Mammalia (/məˈmeɪli.ə/). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three middle ear bones. These characteristics distinguish them from reptiles and birds, from which their ancestors diverged in the Carboniferous Period over 300 million years ago. Around 6,640 extant species of mammals have been described and divided into 27 orders. The study of mammals is called mammalogy.

The largest orders of mammals, by number of species, are the rodents, bats, and eulipotyphlans (including hedgehogs, moles and shrews). The next three are the primates (including humans, monkeys and lemurs), the even-toed ungulates (including pigs, camels, and whales), and the Carnivora (including cats, dogs, and seals).

Mammals are the only living members of Synapsida; this clade, together with Sauropsida (reptiles and birds), constitutes the larger Amniota clade. Early synapsids are referred to as "pelycosaurs." The more advanced therapsids became dominant during the Guadalupian. Mammals originated from cynodonts, an advanced group of therapsids, during the Late Triassic to Early Jurassic. Mammals achieved their modern diversity in the Paleogene and Neogene periods of the Cenozoic era, after the extinction of non-avian dinosaurs, and have been the dominant terrestrial animal group from 66 million years ago to the present.

The basic mammalian body type is quadrupedal, with most mammals using four limbs for terrestrial locomotion; but in some, the limbs are adapted for life at sea, in the air, in trees or underground. The bipeds have adapted to move using only the two lower limbs, while the rear limbs of cetaceans and the sea cows are mere internal vestiges. Mammals range in size from the 30–40 millimetres (1.2–1.6 in) bumblebee bat to the 30 metres (98 ft) blue whale—possibly the largest animal to have ever lived. Maximum lifespan varies from two years for the shrew to 211 years for the bowhead whale. All modern mammals give birth to live young, except the five species of monotremes, which lay eggs. The most species-rich group is the viviparous placental mammals, so named for the temporary organ (placenta) used by offspring to draw nutrition from the mother during gestation.

Most mammals are intelligent, with some possessing large brains, self-awareness, and tool use. Mammals can communicate and vocalise in several ways, including the production of ultrasound, scent marking, alarm signals, singing, echolocation; and, in the case of humans, complex language. Mammals can organise themselves into fission–fusion societies, harems, and hierarchies—but can also be solitary and territorial. Most mammals are polygynous, but some can be monogamous or polyandrous.

Domestication of many types of mammals by humans played a major role in the Neolithic Revolution, and resulted in farming replacing hunting and gathering as the primary source of food for humans. This led to a major restructuring of human societies from nomadic to sedentary, with more co-operation among larger and larger groups, and ultimately the development of the first civilisations. Domesticated mammals provided, and continue to provide, power for transport and agriculture, as well as food (meat and dairy products), fur, and leather. Mammals are also hunted and raced for sport, kept as pets and working animals of various types, and are used as model organisms in science. Mammals have been depicted in art since Paleolithic times, and appear in literature, film, mythology, and religion. Decline in numbers and extinction of many mammals is primarily driven by human poaching and habitat destruction, primarily deforestation. (Full article...)

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The Blue Whale (Balaenoptera musculus) is a marine mammal belonging to the suborder of baleen whales. At up to 33 metres (110 ft) in length and 181 metric tonnes (200 short tons) or more in weight, it is believed to be the largest animal to have ever lived, though some fragmentary dinosaur discoveries such as the colossal Amphicoelias fragillimus may challenge this long-held belief. Long and slender, the Blue Whale's body can be various shades of bluish-gray. There are at least three distinct subspecies: B. m. musculus of the north Atlantic and north Pacific, B. m. intermedia, of the Southern Ocean and B. m. brevicauda (also known as the Pygmy Blue Whale) found in the Indian Ocean and South Pacific Ocean. B. m. indica found in the Indian Ocean, may be another subspecies. As with other baleen whales, its diet consists mainly of small crustaceans known as krill, as well as small fish and squid. lue Whales were abundant in nearly all oceans until the beginning of the twentieth century. For over 40 years they were hunted almost to extinction by whalers until protected by the international community in 1966. A 2002 report estimated there were 5,000 to 12,000 Blue Whales worldwide located in at least five groups. More recent research into the Pygmy subspecies suggests this may be an underestimate. Before whaling the largest population was in the Antarctic, numbering approximately 239,000 (range 202,000 to 311,000). There remain only much smaller (around 2,000) concentrations in each of the North-East Pacific, Antarctic, and Indian Ocean groups. There are two more groups in the North Atlantic and at least two in the Southern Hemisphere.

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Did you know?

...that a polydactyl cat (pictured) is a cat that has more than the usual number of toes on one or all of its paws?
...that Unsinkable Sam was a ship's cat of both the Kriegsmarine and Royal Navy during the Second World War who survived the sinking of all three ships on which he served?
...that Able Seaman Just Nuisance is the only dog to have been officially enlisted in the Royal Navy?
...that the Moscow Water Dog, developed as a water rescue dog, preferred to bite drowning people instead of saving them?
...from its discovery by John Edward Gray in 1850 until a re-assessment in 1981, the Clymene Dolphin was regarded as sub-species of the Spinner Dolphin.
...the Australian Snubfin Dolphin (Orcaella heinsohni) is a recently recognised species of dolphin first described in 2005.

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Image 1
Donkey
Photograph: Lilly M
A 3-week-old donkey (Equus africanus asinus), in Kadzidłowo, Poland. A female donkey is normally pregnant for about 12 months, and usually gives birth to a single foal; twins are rare.
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Image 2
Black rhinoceros
Photo: Jebulon
The skull of a black rhinoceros (Diceros bicornis), a critically endangered species of rhinoceros native to eastern and central Africa. The two horns on the skull are made of keratin, with the larger front horn typically 50 cm (20 in) long. Sometimes, a third, smaller horn may develop.
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Image 3
Sheep
Photograph: Keith Weller/Agricultural Research Service
Sheep are quadrupedal ruminants, typically kept as livestock. Although the name "sheep" applies to many species in the genus Ovis, in everyday usage it generally refers to Ovis aries. One of the first animals to be domesticated, sheep are likely descended from the wild mouflon of Europe and Asia. They are raised for their fleece, meat, and milk.
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Image 4
Leopard seal
Photograph: Godot13
The leopard seal (Hydrurga leptonyx), also known as the sea leopard, is the second largest species of seal in the Antarctic, after the southern elephant seal. Its only natural predators are the killer whale and possibly the elephant seal. It feeds on a wide range of prey including cephalopods, other pinnipeds, krill, birds and fish. Together with the Ross seal, the crabeater seal and the Weddell seal, it is part of the tribe of lobodontini seals.

This image shows a yawning leopard seal in the Antarctic Sound in 2016. See also the same seal in profile.
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Image 5
Sahelanthropus tchadensis
Photo: Didier Descouens
A cast of the extinct hominid species Sahelanthropus tchadensis holotype cranium, dubbed "Toumaï", in facio-lateral view. The original cranial fragment is dated to about 7 million years ago and was discovered in Chad. Other than Toumaï, the only Sahelanthropus remains to be discovered are five pieces of jaw and some teeth.
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Image 6
Lesser short-nosed fruit bat
Photo: Anton Croos
A newborn lesser short-nosed fruit bat (Cynopterus brachyotis) clinging upon a human finger. A species of megabat within the family Pteropodidae, it is a small bat that lives in South and Southeast Asia. Adults weigh between 21 and 32 grams (0.74 and 1.13 oz).
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Image 7
Olive baboon
Photo: Muhammad Mahdi Karim
The olive baboon (Papio anubis) is an Old World monkey found in 25 countries throughout Africa, making it the most widely ranging of all baboons. It is named for its coat, which, at a distance, is a shade of green-grey. At closer range, its coat is multi-colored, due to rings of yellow-brown and black on the hairs. It is omnivorous, finding nutrition in almost any environment, and able to adapt with different foraging tactics.
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Image 8
Steenbok
Photograph: Yathin S Krishnappa
The steenbok (Raphicerus campestris) is a species of small antelope, generally standing 45–60 centimeters (16–24 inches) at the shoulder, commonly found in Africa. They live in a variety of habitats, from semi-desert to open woodland and thickets, and feed on low-level vegetation and roots. These common animals are typically solitary, except during mating season.
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Image 9
Koala
Photo: JJ Harrison
A female koala (Phascolarctos cinereus), an arboreal herbivorous marsupial native to coastal regions of eastern and southern Australia. The word "koala" comes from the Dharuk word gula. English-speaking settlers from the late 18th century first called it "koala bear" due to its similarity in appearance to bears, although they are not at all related. Instead, its closest living relative is the wombat.
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Image 10
Lar gibbon
Photograph: JJ Harrison
The lar gibbon (Hylobates lar) is a primate found in South-East Asia. This endangered gibbon species is primarily a frugivore, but may also feed on leaves, flowers, and insects.

This specimen was photographed in Kaeng Krachan National Park, Phetchaburi, Thailand.
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Image 11
California Ground Squirrel
Photo credit: Howard Cheng
The California Ground Squirrel (Spermophilus beecheyi) is a common and easily observed ground squirrel of the western United States and the Baja California peninsula. Their upper parts are mottled, the fur containing a mixture of gray, light brown and dusky hairs. Head and body are about 30 cm (12 in) long and the tail an additional 15 cm (5.9 in).
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Image 12
Giraffe
Photo: Muhammad Mahdi Karim
A giraffe extending its tongue to feed. Its tongue, lips and palate are tough enough to deal with sharp thorns in trees. Giraffes prefer trees of the genera Acacia, Commiphora and Terminalia. A giraffe requires less food than typical grazing animals, typically consuming 65 pounds (29 kg) of leaves and twigs daily, because the foliage it eats has more concentrated nutrition and it has a more efficient digestive system.
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Image 13
Goat kid
Photo credit: Fir0002
A 2-month old domestic goat (Capra aegagrus hircus) kid in a field of capeweed. Goats are one of the oldest domesticated species. For thousands of years, goats have been used for their milk, meat, hair, and skins over much of the world. Female goats are referred to as does or nannies, intact males as bucks or billies; their offspring are kids.
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Image 14
Topi
Photograph: Charles J. Sharp
Female topi (Damaliscus lunatus jimela) in the Queen Elizabeth National Park in Uganda. A subspecies of the common tsessebe antelope, the topi is native to several countries in eastern Africa and lives primarily in grassland habitats, ranging from treeless plains to savannas. It is a tall species, with individuals ranging in height from 100 to 130 cm (39 to 51 in) at the shoulder. Predators of topi include lions and spotted hyenas, with jackals being predators of newborns.
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Image 15
Cheetah
Photograph credit: Charles James Sharp
The cheetah (Acinonyx jubatus) is a large cat native to Africa and central Iran. Cubs are highly vulnerable to predators during the first few weeks of life, and predation is the leading cause of mortality among cheetah cubs. A study showed that in areas with a low density of predators (such as Namibian farmlands) around 70 per cent of the cubs survived beyond the age of 14 months, whereas in areas like the Serengeti National Park, where several large carnivores exist, the survival rate was just 17 per cent. This cheetah cub was photographed in the Phinda Private Game Reserve in KwaZulu-Natal, South Africa, amid long grass.
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Scientific classification

Kingdom→ Animalia Phylum→ Chordata Subphylum→ Vertebrata Superclass→ Tetrapoda (unranked)→ Amniota Class→ Mammalia

Subclasses and Infraclasses

Subclass †Allotheria*
Subclass Prototheria
Subclass Theria
- Infraclass †Trituberculata
- Infraclass Metatheria
- Infraclass Eutheria

* Member of a haplogroup and not any of its subclades.
† Taxon is extinct.

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