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mammal : any of a class (Mammalia) of warm-blooded higher vertebrates (such as placentals, marsupials, or monotremes) that nourish their young with milk secreted by mammary glands, have the skin usually more or less covered with hair, and include humans — Webster

OneLook, Free Dictionary, Wiktionary


Mammals are the vertebrates within the class Mammalia, a clade of endothermic amniotes distinguished from reptiles (including birds) by the possession of a neocortex (a region of the brain), hair, three middle ear bones, and mammary glands. Females of all mammal species nurse their young with milk, secreted from the mammary glands.

Mammals include the largest animal on the planet, the blue whale. The basic body type is a terrestrial quadruped, but some mammals are adapted for life at sea, in the air, in trees, underground or on two legs. The largest group of mammals, the placentals, have a placenta, which enables the feeding of the fetus during gestation. Mammals range in size from the 30–40 mm (1.2–1.6 in) bumblebee bat to the 30-meter (98 ft) blue whale. With the exception of the five species of monotreme (egg-laying mammals), all modern mammals give birth to live young. Most mammals, including the six most species-rich orders, belong to the placental group. The largest orders are the rodents, bats and Soricomorpha (shrews and allies). The next three biggest orders, depending on the biological classification scheme used, are the Primates (apes and monkeys), the Cetartiodactyla (whales and even-toed ungulates), and the Carnivora (cats, dogs, seals, and allies). — Wikipedia

Encyclopædia Britannica


Mammals – Mammalogy (Martindale’s Reference Desk)





Mammals (Smithsonian National Museum of Natural History)


WorldCat, Library of Congress, UPenn Online Books, Open Library




Introducing the Mammals (Biology4Kids)


OER Commons: Open Educational Resources



Science Daily,, NPR Archives






More News …

Mammals News -- ScienceDaily Mammals in the news, wild mammals, mammal conservation efforts, and domesticated mammals.

  • Increasing evidence that bears are not carnivores
    on October 3, 2022 at 1:06 pm

    Bears are not cats or dogs, and feeding them like they are likely shortens their lives. A new study on the diets of giant pandas and sloth bears adds more evidence that bears are omnivores like humans and need a lot less protein than they are typically fed in zoos.

  • Evidence of social relationships between...
    on September 30, 2022 at 6:52 pm

    Drawn from more than 20 years of observations at Nouabalé-Ndoki National Park in the Republic of Congo, researchers documented lasting social ties between individual chimpanzees and gorillas that persisted over years and across different contexts.

  • Revealing the genome of the common ancestor of...
    on September 28, 2022 at 1:48 pm

    An international team has reconstructed the genome organization of the earliest common ancestor of all mammals. The reconstructed ancestral genome could help in understanding the evolution of mammals and in conservation of modern animals. The earliest mammal ancestor likely looked like the fossil animal 'Morganucodon' which lived about 200 million years ago.

  • Browse, graze, mate: Food and company help...
    on September 27, 2022 at 11:26 pm

    From tongue rolling alpacas to irritable yaks and perturbed pigs, new research has lifted the lid on why some farm and zoo animals cope well with captivity and others display signs of stress. Researchers have published a large-scale study to identify which species of hoofed animals, known as ungulates, are better suited to captive environments and which require better husbandry if kept in captivity.

  • Study finds all African carnivores at risk for...
    on September 27, 2022 at 12:07 am

    A new study assessing 91 African carnivores to identify gaps in capacity necessary for their conservation found that many species that are currently classified as 'least concern' on the International Union for the Conservation of Nature Red List of Threatened Species had high percentages of their range at risk of contraction. - latest science and technology news stories internet news portal provides the latest news on science including: Physics, Nanotechnology, Life Sciences, Space Science, Earth Science, Environment, Health and Medicine.

  • Long-term tracking of whale feeding behavior via...
    on October 3, 2022 at 8:39 pm

    Oregon State University researchers have developed a new satellite tag that allows them to better track whales' behavior, including previously unobservable feeding events during dives.

  • New research demonstrates connection between...
    on October 3, 2022 at 8:00 pm

    Some 250 million years ago—long before dinosaurs roamed the earth—global warming and acid oceans caused by the rapid volcanic emission of the Siberian Traps led to the Permian-Triassic mass extinction, which resulted in the elimination of over 95% of marine and 70% of terrestrial life.

  • Studying yeast DNA in space may help protect...
    on October 3, 2022 at 4:08 pm

    Nuclear fusion reactions in the sun are the source of heat and light we receive on Earth. These reactions release a massive amount of cosmic radiation—including X-rays and gamma rays—and charged particles that can be harmful for any living organisms.

  • How do bacteria evolve in the gut over the course...
    on October 3, 2022 at 4:03 pm

    Our bodies go through several changes throughout our lives. The same happens with the microbes that live with us. After all, these make up a big portion of the cells in our organism. But, in comparison with the cells that make up our tissues and organs, these microbes divide very quickly, making occasional errors in their genetic material (mutations) more common. These errors drive the evolution of microorganisms and account for, among other things, their likelihood of causing disease.

  • What is a wetland? An ecologist explains
    on October 3, 2022 at 3:30 pm

    Wetlands are areas of land that are covered by water, or have flooded or waterlogged soils. They can have water on them either permanently or for just part of the year.


Here are links to pages about closely related subjects.

Knowledge Realm


Sphere Land, Ice, Water (Ocean), Air
Ecosystem Forest, Grassland, Desert, Arctic, Aquatic

Life Cell, Gene, Tree of Life
Plant Flower, Tree
Invertebrate Cuttlefish, Octopus, Ant, Bee, Butterfly, Spider, Lobster
Vertebrate Fish, Seahorse, Ray, Shark, Frog, Turtle, Tortoise, Dinosaur
Bird, Ostrich, Owl, Crow, Parrot
Mammal Bat, Rabbit, Giraffe, Camel, Horse, Elephant, Mammoth
Whale, Dolphin, Walrus, Seal, Polar Bear, Bear, Cat, Tiger, Lion, Dog, Wolf
Monkey, Chimpanzee, Human


1.   The resources on this page are are organized by a classification scheme developed exclusively for Cosma.