Question

What are the characteristics of mammals?

Answer 1

Hint: Mammals belong under the subphylum Vertebrata and superclass Tetrapoda. The study of mammals is known as mammalogy. Most of their characters are characters of vertebrates and tetrapods. They can maintain a constant internal environment. They have well-developed organ systems.

Complete answer:
Mammals originated during the Triassic period of the Mesozoic era. The Cenozoic era is known as the Golden age of mammals.

The characteristic of organisms belonging to class Mammalia are:
-They are warm-blooded organisms.
-The presence of hair and mammary glands is observed in mammals.
-Mammals are found in all kinds of habitats.
-Sebaceous glands or oil glands and sweat glands or sudoriferous glands are present throughout their skin.
-Cervical neck vertebrae are present in mammals.
-Four chambered heart is found in mammals
-RBCs or red blood cells are enucleated
-Skull is dicondylic
-Sinus venous and the renal portal system is absent in mammals
-The excretory system consists of metanephric kidney and they are ureotelic (major excretory product is urea)
-Heterodont, diphyodont, and thecodont type of dentition is found.
-Almost all mammals are viviparous
-The muscular diaphragm is seen in mammals only and divides the trunk into thorax and abdomen.
-Coelom consists of four cavities, a pericardial cavity, 2 pleural cavities, and one peritoneal cavity.
-They are divided into three subclasses including Prototheria, Metatheria, and Eutheria.

Note: It should be remembered that the mammals belonging to subclass Prototheria are oviparous. Several other features like pinnae, nipples, etc are also absent in prototherian mammals. No scrotum is present and testes are abdominal. Placenta formation is also not seen in mammals belonging to subclass Prototheria. Examples are the duck-billed platypus and spiny anteater. Mammals belong under Vertebrate and subphylum Tetrapoda.