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A mammal (from Latin mamma 'breast') [1] is a vertebrate animal of the class Mammalia ( / məˈmeɪli.ə / ). Mammals are characterized by the presence of milk-producing mammary glands for feeding their young, a neocortex region of the brain, fur or hair, and three middle ear bones.
- Overview
- Diversity
An animal is considered a mammal if it can produce milk. Other features unique to mammals include hair or fur (chemically different from hairlike structures on non-mammals); the malleus, incus, and stapes in the ear; and a diaphragm separating the heart and lungs from the abdomen. Also, mammals lack nuclei in mature red blood cells.
How many species of mammals are there?
It is estimated that there are more than 5,500 living mammal species. Mammals are incredibly diverse and can be found in every major habitat.
What is the biggest mammal?
The biggest living mammal—indeed, the largest animal ever—is the blue whale. It can be as heavy as 180 metric tons (200 short tons) and reach a length of more than 30 metres (98 feet).
Did mammals and dinosaurs exist at the same time?
The evolution of the class Mammalia has produced tremendous diversity in form and habit. Living kinds range in size from a bat weighing less than a gram and tiny shrews weighing but a few grams to the largest animal that has ever lived, the blue whale, which reaches a length of more than 30 metres (100 feet) and a weight of 180 metric tons (nearly 200 short [U.S.] tons). Every major habitat has been exploited by mammals that swim, fly, run, burrow, glide, or climb.
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There are more than 5,500 species of living mammals, arranged in about 125 families and as many as 27–29 orders (familial and ordinal groupings sometimes vary among authorities). The rodents (order Rodentia) are the most numerous of existing mammals, in both number of species and number of individuals, and are one of the most diverse of living lineages. In contrast, the order Tubulidentata is represented by a single living species, the aardvark. The Uranotheria (elephants and their kin) and Perissodactyla (horses, rhinoceroses, and their kin) are examples of orders in which far greater diversity occurred in the late Paleogene and Neogene periods (about 30 million to about 3 million years ago) than today.
The greatest present-day diversity is seen in continental tropical regions, although members of the class Mammalia live on (or in seas adjacent to) all major landmasses. Mammals can also be found on many oceanic islands, which are principally, but by no means exclusively, inhabited by bats. Major regional faunas can be identified; these resulted in large part from evolution in comparative isolation of stocks of early mammals that reached these areas. South America (the Neotropics), for example, was separated from North America (the Nearctic) from about 65 million to 2.5 million years ago. Mammalian groups that had reached South America before the break between the continents, or some that “island-hopped” after the break, evolved independently from relatives that remained in North America. Some of the latter became extinct as the result of competition with more advanced groups, whereas those in South America flourished, some radiating to the extent that they have successfully competed with invaders since the rejoining of the two continents. Australia provides a parallel case of early isolation and adaptive radiation of mammals (specifically the monotremes and marsupials), although it differs in that Australia was not later connected to any other landmass. The placental mammals that reached Australia (rodents and bats) evidently did so by island-hopping long after the adaptive radiation of the mammals isolated early on.
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Feb 9, 2017 · Definition Of A Mammal: A Member Of Mammalia. Some of the world's biggest mammals – such as this humpback whale – are mammals. Scientifically speaking, a mammal is a member of a ‘ class ’ of animal called ‘ Mammalia ’. A ‘ class ’ is a group of animals that have certain things in common. Scientists like to put animals into ...
Jul 12, 2022 · One can also go more into depth about the structure and reproduction and growth characteristics of animals. Kingdom Animalia is a taxonomic kingdom of living and extinct animals. Members of this kingdom are characterized by being eukaryotic, multicellular, heterotrophic, lacking a cell wall, and mostly are motile.
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Jan 30, 2023 · Animal Classification: The Six Different Animal Kingdoms All living organisms can be placed in one of six different animal kingdom classifications. The characteristics of each animal kingdom are: Animal – A kingdom of complex multi-celled organisms that do not produce their own food. This kingdom contains all living and extinct animals.
Nov 7, 2020 · Looking through kingdom examples can help you identify different organisms around the world. Learn more about the six kingdoms with this extensive list.
The taxon to which mammals belong is the Class Mammalia, which is in the Phylum Chordata in the Kingdom Animalia. Placing mammals in one Class indicates that they are more closely related to one another than any mammal is to an animal in a different Class. Mammals have many physical characteristics that make them distinct from other animals.
