Mammals are there, everywhere you look; large warm-blooded, four-limbed vertebrates whose females produce milk (What is a Mammal). Elephants and Whales, Pigs, Horses, Cattle, Sheep, Dogs, Cats, Hamsters, Rats and of course Human beings are all mammals. Mammals are friendly or fierce, cuddly, cute and/or awesome depending on which ones you look at. They fascinate and horrify us. We eat them, hunt other mammals with them and use them, hunt other mammals with them and use them as substitutes for ourselves in scientific, particularly medical, research. We use them to carry our burdens. To most people animals are mammals. Most people are totally dependent on non-human mammals to keep their lives functioning and many of us need them as emotional supports as well. Mammals may have only become successful as a group relatively recently, but they have been around a long time. The first mammals appeared about 265 million years ago, a mere 10 million years after the first dinosaurs, but they remained relatively obscure for the first 160 million years while the dinosaurs ruled.
Placental Mammals are a rather diverse group, with nearly 4000 described species, mostly rodents and bats. The placental mammals include such diverse forms as whales, elephants, shrews and armadillos. They are also some of the most familiar organisms to us, including pets such as dogs and cats, as well as many farm and work animals, such as sheep, cattle and horses. And humans, of course, are also placental mammals. Mammals are placental basically because they their young ones are developed inside womb of mother. Placenta is an organ embedded in the womb of mother. It carries nutrients for the baby inside.
Pouched mammals include such animals as the Kangaroo, Kola, Opossum and Wallaby. They are notable because they have pouches in which they place their young when they are born. This pouch is near the mammary glands so the mother can nurse the young animals. When they are big enough, they leave the pouch and are on their own.
Monotremata is the most ancient living order of mammals. In addition to being egg layers, members of their order share skeletal features such as the shoulder girdle and skull characteristics that have been lost in other living mammals. Certain features of the skull appear to link monotremes to the extinct early mammals groups. Other evidence, particularly genetic data, places Monotremata close to more-advanced mammals, namely marsupials.
The echidna has a small tail and a narrow beak. There are short-beaked echidnas and long-beaked echidnas. The mouth is toothless and very tiny. Everywhere except the belly, it is covered with coarse hairs and short, pointy spines. Each foot has five toes with strong claws. On each hind foot there is an extra long, curved claw on the second toe; the echidna uses this claw to clean between it’s spines. Males grow to about 13.5 to 17.5 inches in length and weigh about 6.5 to 14.5 pounds. Females are somewhat smaller.
The primates include the most familiar of the placental mammals, because they include us, Homo sapiens. Primates also include familiar animals, such as the Chimpanzees, gorillas and monkeys as well as the somewhat less familiar lemurs, lorises, galagos, pottos, sifakas, indris, aye-ayes and tarsiers.
Mammary glands, the sourse of milk, are unique to mammals, as is milk itself, through pigeons produce something similar in their crops for their young. Mammary glands are what give our class of animals their name. We are the mammals or the mammary gland possessing animals. Mammary glands are modified sweat glands and are not the same as the nipples or teats through which most young mammals obtain the milk secreted by the mammary glands. Through all mammals have teats. The exceptions are the two monotremes the Echidna and the Platypus.
Mammals during pregnancy can have one or more gestations at the same time. The time interval of a gestation plus 2 weeks is called gestation period, and the length of time plus 2 weeks that the offspring have spent developing in the uterus is called gestational age. The extra 2 weeks is because gestational age is counted starting from the last menstrual period, rather than actual conception. However this extra 2 weeks is not always added when talking about animals.
Mammals have several unique characteristics that differentiate them from other animals. They are warm blooded as they are capable of regulating their body temperature. The mammals metabolism controls heat production, and the sweat glands help cool the body. These allow the mammal to maintain a constant body temperature, regardless of the environmental temperature. One other difference is that mammals give birth to fully formed babies, and the female mammals produce milk to feed their young.
Facts about Mammals
There are more than 4200 species of mammals. All but two give birth to live young. The other two the Duck-Billed Platypus and the Echidna – hatch their young from eggs.
Elephants have huge feet and can weigh more than five tons. But they have big, soft, spongy feet that spread their weight out so well they barely even leave footprints.
Eucalyptus is used to make cough drops — and because Koala bears eat so much eucalyptus, they smell like cough drops. The smell helps them keep fleas away.
A female Pacific Grey Whale gestates and delivers a 2000 pound baby, migrates over 10,000 miles, and produces 6 tons of breast milk without eating a bite of food — using just her blubber for fuel.
Many mammals spend their childhood running, jumping and playing but giraffe claves play less because they need to use their energy to grow. Giraffes protect themselves by being big, so their goal is to grow as large as they can, as fast as they can.
Shrews have so little body fat they cannot go more than a couple of hours without food. Missing a meal is a sure way to a quick death. A good night’s sleep could be fatal.
Hooded seals go from infancy to childhood to adolescence to adulthood in just four days -the shortest childhood of any mammal.
Bats hang upside-down because they can’t stand right-side up. Their leg bones are too thin to hold up their bodies.
A polar bear looks white, but he isn’t really. His long, shaggy hairs are colourless and hollow. Beneath his hair, the skin is black.