Class mammalia is a small group of animals. It includes about 5400 species of mammals including human beings, bats, cats, tigers, elephants, pandas, gorillas, mice, sloths, horses, dolphins and whales. Mammals are sub-categorized as monotremes (Prototheria), marsupials (Metatheria) and placental mammals (Eutheria) on the basis of their mode of reproduction. Monotremes are the egg-laying mammals such as duck-billed platypus and echidnas. Marsupials include kangaroo, koala and numbat. Most mammals are the placental mammals.
Mammals are categorized according to their diets, e.g., herbivores (plant eaters) such as cows, pandas, horses, etc; carnivores (meat eaters) such as tigers, lions, dogs, whales and dolphins; omnivores (eating plants and meat) such as human being, some bears; and insectivores (eat insects) such as anteaters, aardvarks and pangolins. Blue Whale is the largest mammal, while giraffe is the tallest mammal on the earth. Kitti’s Hog-nosed bat is the smallest mammal in the world.
Facts about Mammals
Here are some interesting facts about mammals that will help you to explore the secrets of mammals and their characteristics.
Mammals are the warm-blooded, hairy, air-breathing and milk-producing animals. Almost all the mammals live on land. Bats are the only mammals that are capable of flying. Dolphins and whales are the aquatic mammals.
Mammals are able to maintain a constant body temperature, irrespective of the environmental temperature. An average body temperature of mammals ranges from 90-104F.
Most mammals have varied teeth types including molars, premolars, incisors and canines. The incisors are used for cutting, molars and premolars for shearing or grinding and canines for tearing. Mammals chew their food and make it ready for a quick digestion.
Mammals give birth to the young ones, rather than laying eggs. Duck billed platypus is an exception, which lays eggs. Metatherians have a marsupium or brood pouch, in which the immature young ones are kept and fed. The young ones of the mammals are fed on mother’s milk.
All the mammals are the vertebrate animals. The number of cervical vertebrae is 7 in all mammals, except in sea cow. There are 8 vertebrae in sea cow. Sinus venosus is modified into the superior and inferior vena cava in mammals.
Mammals have a highly efficient circulatory system. The four-chambered heart is one of the exceptional characters of the mammals. Mammals breathe air, even the aquatic mammals. Their lungs are large and play an important role in the exchange of oxygen and carbon dioxide.
The mammalian skin consists of several types of glands. The mammary glands are a peculiar feature of the mammals. These glands produce the milk, which provides nourishment to the young ones during their postnatal period of growth. Mammal’s milk is rich in proteins, carbohydrates and fats.
The brain of mammals is complex and highly developed. The lower jaw in mammals is made from a single bone. The middle ear of mammals contains 3 bones such as Stapes (Stirrup), Malleus (Hammer) and Incus (Anvil).
All the mammals possess a diaphragm, a sheet of tendons and muscles that divides the body cavity into two sections. Lungs and heart are in the upper section, while liver, stomach, intestine and kidneys are in the lower section.