Mammal

Mammal or class Mammalia is a group of most advanced animals concerning evolutionary aspects. Class mammals belong to the subphylum Vertebrata or Craniata. The notochord of vertebrates converted to a veritable column during the embryo stage. Among all vertebrates, mammals have the most advanced evolutionary features. Mammals' meaning suggests the presence of mammary glands in the female suckling the young ones. The number of species is around 5500. Mammals originated in the Triassic, about 200 million years ago. From the depth of the sea to the top of the mountain, from warm desert to cold antarctic, they occupy almost every part of the earth for being more adaptable than any other single class of animals. The most important information about mammals is that the largest animals both overland and inside water are mammals. Class Mammalia consists of three major subclasses Prototheria, Metatheria, Eutheria. For such huge diversity and some typical mammalian characteristics, the class mammal is so important.

Characteristics of the Class Mammal

If one asks what is meant by mammals, the answer should be mammals are the animals, belong to the class Mammalia which is characterised by some typical mammalian features. Such mammalian features include the presence of mammary glands in the female for feeding the young ones. The bodies of mammals are covered by epidermal hair. Generally, mammalians are exothermic and warm-blooded. They are generally tetrapods. The presence of pinna is a piece of major information about mammals. Their body consists of two types of glands: sweat gland and sebaceous gland, their endoskeleton is generally made up of bones.

The most unique feature of Mammalians is their heart is four-chambered. It ensures a clear separation between oxygenated and deoxygenated blood. A salient feature of the class mammal is that the thorax and abdominal cavity are separated by the diaphragm. Respiratory and digestive tracts are separated and an epiglottis is present over the glottis. Their lungs are well developed. The urinary bladder is present and the kidneys are metanephric. Mammals show internal fertilisation. Mammals are generally viviparous where the foetus is nourished by the mother through the placenta. Their jaw is directly connected to the skull. Another salient feature of class mammal is the absence of a nucleus in red blood cells. To state mammal definition one should add the above-mentioned features.

Classification of Mammals

The answer to the question of what is a mammal should be is the animals having a mammary gland as the main mammalian feature. Based on evolution class Mammalia is classified into three major subclasses Prototheria, Metatheria, Eutheria. 

Subclass Prototheria are primitive mammals. The most interesting feature of this subclass is that they are oviparous. External pinnae are absent and the testes are abdominal. They are called unfinished mammals. Such primitive mammals examples include Platypus, Spiny Ant Eater, etc. On the other hand subclass, Metatheria is characterised by their marsupial sac for keeping and nourishing the young ones. They are also called pouched mammals or marsupials. Such Metatherian mammals examples include Kangaroo, Koala, Opossum, etc. Interestingly Metatherians are found only in Australia and nearby islands. Subclass Eutheria has a well-developed placenta for nourishing the foetus. The marsupial sac is absent here and the pinnae are well developed. Such Eutherian mammals examples include a large number of animals. For example humans, monkeys, lions, elephants, etc.

Diversity of Class Mammalia

Due to the greater adaptive abilities class, Mammalia shows a huge diversity in form of size, habit, reproduction. A large variety of physical, physiological, behavioural adaptations are noticed in class Mammalia. Mammalians occupy the whole earth from desert to super cool regions. Every major habitat is occupied by various kinds of mammals. The ability to regulate body temperature makes them superior to other animals. They can tolerate both excessive heat and severe cold. Due to this dominance, the current Cenozoic era is known as the age of mammals.  

The number of species is around 5500 under the class Mammalia. It includes a large number of orders and they show plenty of diversities. The largest animals both overland and inside water are mammals. Among all Mammalians Rodents are the most abundant. The tropical region shows the greatest diversity of mammals. Though the majority of mammals are terrestrial, aquatic mammals are not very uncommon, for example Dolphins, Whales, the largest aquatic animal. It can be thus said that we are surrounded by lots of mammals.

Examples of Mammals

Class Mammalia consists of a large number of species. A huge number of orders come under the subclass Eutheria. Order Insectivora includes Moles, Shrews, etc. Order Chiroptera includes Small Bats. Examples of order Lagomorpha are Rabbits, Hares. Order Rodentia is the largest order under the class Mammalia. It includes Rats, Mice, Guinea Pigs, Squirrels etc. Whales and Dolphins are examples of order Cetacea. Lions, Tigers, Wolves, Dogs, Bears are placed under order Carnivora. The largest land animal elephants are placed under the order Proboscidea. The hippopotamus is placed under the order Artiodactyla. Order primate is the most advanced of all mammals. Gorilla, Lemur, chimpanzee, Human, etc are some examples of order Primata. 

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Importance of Mammalians

Mammals are an integral part of humans. To state who are mammals, it should be mentioned that mammals are the most advanced animals belonging to class Mammalia. We know we humans are developed from monkeys by different levels of evolution. To understand the evolutionary chain of the human species, the study of mammalian features are extremely important. Moreover, humans are now economically dependent on mammals for food and clothes. Such an economical relationship is so important to compensate for the food crisis due to overpopulation. Mammals play a vital role to make balance in their corresponding ecosystems. Sometimes mammals give some source of medicines for different diseases. Monkeys, rats are used for biological experiments. Thus mammalians are very closely related to human life.

Global Warming and Mammalia

Global warming is now a major threat to Mammalian existence. The climatic change due to global warming causes habitat loss and with such rapid change of climate, all mammalians cannot adopt. As a result, many mammalians are on the verge of extinction. The International Union for Conservation of Nature (IUCN) prepared a list of endangered species which need to be protected, the list is known as the red data list. Such endangered mammals are to be reserved artificially. Such rapid extinction needs to be controlled as soon as possible to maintain the balance of the ecosystem.  

According to IUCN data, there are 679 endangered mammalian species. Such information about mammals is alarming. The endangered mammalian species involves Royal Bengal Tigers, Asiatic Lions, Rhinoceros, Bears, Leopards, Giant Pandas, Asian Elephants, Fin Whales, Irrawaddy Dolphins, Sea Lions, Jaguars, Polar Bears, Arctic Foxes, Brown Bears, Sloths, etc.

Conclusion

Class Mammalia is the most advanced class in the animal kingdom based on evolutionary features. A large variety of physical, physiological, behavioural adaptations are noticed in class Mammalia. The ability to regulate body temperature makes them superior to other animals. Due to this dominance, the current Cenozoic era is known as the age of mammals. To understand the evolutionary chain of the human species, the study of mammalian features are extremely important. That is why class Mammalia is so important. But there is the rapid loss of mammalian species due to global warming and we should look into this matter for the sake of the ecosystem. 

Did You Know?

1. The current Cenozoic era is known as the age of mammals. Due to the greater adaptive abilities class, Mammalia shows a huge diversity in form of size, habit, reproduction. A large variety of physical, physiological, behavioural adaptations are noticed in class Mammalia. Mammalians occupy the whole earth from desert to super cool regions. Every major habitat is occupied by various kinds of mammals. The ability to regulate body temperature makes them superior to other animals.

2. The International Union for Conservation of Nature (IUCN) prepared a list of endangered species which need to be protected, the list is known as the red data list. According to IUCN data, there are 679 endangered mammalian species. The endangered mammalian species involves Royal Bengal Tigers, Asiatic Lions, Rhinoceros, Bears, Leopards, Giant Pandas, Asian Elephants, Fin Whales, Irrawaddy Dolphins, Sea Lions, Jaguars, Polar Bears, Arctic Foxes, Brown Bears, Sloths, etc.