Question

List out the characteristic features of the mammals in the animal kingdom.

 

Answer 1

The Mammals

• The animal kingdom has two subdivisions, namely. Protozoa and Metazoa.
• The metazoa includes Invertebrate and Vertebrate.
• The vertebrate is subdivided into five classes. These are Fish, Amphibian, Bird, Reptile and Mammal. Man belongs to the class mammal.
• The mammals have certain characteristic features by which they are distinguished from the other four classes of vertebrate.
• Some of these are as follows:
  • The mammals are warm-blooded, air-breathing vertebrate having epidermal covering in the form of hair.
  • They are called viviparous, because they do not lay egg.
  • The mother nourishes the fetus with the blood system through placenta.
  • After birth breast milk of the mother is the source of nourishment.
  • The vertebral column has intervertebral discs. Each vertebra has three primary centers of ossification, one for the body and the other two for the arch.
  • A long bone consists of two epiphyses and a shaft.
  • The vestige of coracoid contributes to the formation of the pectoral girdle.
  • There are two condyles on the two sides of the foramen magnum in the skull, which articulate with the atlas.
  • The mammals have two sets of teeth (diphyodont), one is deciduous and the other is permanent.
  • The teeth are embedded in sockets (thecodont) and are of different shapes (heterodont).
  • The articulation between the skull and the jaw is direct without any intermediation of quadrate bone.
  • A partly muscular and partly tedious diaphragm divides the body cavity into one anterior thorax and a posterior abdomen Within the cavity of the thorax the lungs are freely.
  • Each half of the heart consists of a ventricle and an suspended auricle and hence the heart has four chambers.
  • The mammals have an epiglottis, which is a movable plate guarding the opening of the larynx.
  • The red blood corpuscles (RBC) are circular and not nucleated.
  • A corpus callosum unites the cerebral hemispheres.
  • The pons varolii join the two halves of the cerebellum.

 Animal Kingdom:

The animal kingdom is defined as the basic group of natural objects that includes all living and extinct animals.