Mammals are animals just like birds, fish, and insects. However, there are certain characteristics that mammals share which separate them from other animals. Two things that always set mammals apart are milk production and the growth of hair or fur.
All female mammals have mammary glands which make milk for their young, and only mammals suckle their young from mammary glands. Most mammal babies suckle milk from their mother’s teats. Some mammals do not have teats so their babies suckle on hairs near the mammary glands. Mammal young often stay with their mothers for an extended period of time, though they usually do not be feed on milk for the whole time. They mature more slowly than most other animals and need more looking after by their mothers to become healthy adults.
All mammals have some component of hair or fur, something no other animal has. It may be coarse, stray hairs like on the chin of a whale or a thick, fur coat like on a bison. The coat of most mammals has guard hairs or longer hairs that protect the soft underhair. Guard hairs may develop into quills like you would see on a porcupine. Hair or fur is used to keep mammals warm and to help keep their body temperature constant, which is called being warm - blooded or endothermic. The underhairs provide most of this warmth.
Some characteristics such as live birth and being warm-blooded, are shared by most mammals but may also be seen in other animals.
All mammals are warm blooded, or endother-mic, which means they can regulate their body temperature separately from the environment. For example, the musk ox can keep a body temperature well above the frigid tempera-tures of the arctic. Cold-blooded or ectothermic animals like reptiles or fish have body temperatures that change according to the surrounding temperature. Mammals must eat a lot more than ectothermic animals to make this body heat and they use their hair or fur to keep the heat from being lost to the environment. Some mammals with just a little hair or fur, such as whales, have a layer of fat called blubber to help insulate them from the cold.
Most mammals give birth to live young as opposed to laying eggs. The young develop inside the mother and are nourished by a placenta. Sometimes there are exceptions to this rule. For example, a small group of mammals including the platypus do lay leathery eggs. There are also certain species of snakes and sharks, animals that are not mammals, which give birth to live young.
One group of mammals called marsupials give birth to live young, but the babies need to spend time in their mother’s pouch before they are completely developed. There are no egg laying mammals here in California and only one marsupial, the opossum.
Humans share all four of these characteristics with other mammals: live birth, milk production, hair or fur, and endothermy. Women give birth to live babies and are able to produce milk to nourish them. We have a large amount of hair on our heads and small amounts on the rest of our bodies. Lastly, humans are endothermic with a constant body temperature. One way doctors can tell if we are sick is by looking for changes in our temperature. When it gets higher than normal, we have a “fever”.
Natural
History Museum of Los Angeles County, 900 Exposition Boulevard,
Los Angeles, CA 90007 (213) 763-DINO general
information l contact us I privacy
policy I copyright l membership
I shop I jobs
l volunteer l search
l site map
Natural History Family of Museums
©Copyright 2004
"Mammal Safari"er