Question

Explain class-mamalia with diagram .

Answer 1

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1. class mammalia developed during cnezozoic era
2. study of mammals is called mammology
3. most of the mammals are terrestrial and some are aquatic and few other are flying
4. body is divided into distinct head, neck, trunk and tail
5. there are two pairs of limbs i.e., forelimbs(webbed wings/hands) and hind limbs (legs)
6. skin has sweat glands and sebaceous glands.
7. exoskeleton is homeothermic and has hair (except whale and armodillus)
8. endoskeleton is made of bones with skull and vertebral column (with vertebrae), alveolus vertebrae i.e. flat vertebrae is dicondylic.
9. diaphragm is present between thorax and abdomen and also separate them.
10. digestive system starts with mouth (heterdont dentition) and ends with anus.
11. respiratory organs are lungs
12. circulatory system is described as double circulation and heart is with 4 chambers.
13. excretion through nephrons (kidney) and excrete urea.
14. brain is covered by three meninges namely.,duramater, archenoid membrane and piamater) and is represented by lobes.
15. fertilization is internal and development is indirect.

Answer 2

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$\pink\bigstar$Class Mamalia :-

• This are develop during coenzoic era (approximately 70 - 65 mammals).

• All the mammals posses hair on their skin except aquatic mammals.

• They give direct birth to their young one except platypus.

• Show very high level of parental care and feed their young one through the secretion of mammary gland.

• They posses well cranial nerve brain very well developed and control the function of the body through CNS and spinal cord.

• In a mammals vertebrae is connected to one another by fibroblast cartilage.

• Respiration takes place through nose.

• Senses are separated, internal fertilization, development is direct, gender of new one is determine by male.

• Largest mammal is blue whale, Terrestrial and extinct mammoth.

• eg - Platipus (orlythorchynctius).

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