Thursday, January 2, 2014

Class mammalia-general characters

1.Mammals are warm blooded animals
2.Skin with hairs ,sweat and sebaceous glands.
3.Mammry glands well developed in females to nourish the young ones
4.Presence of pinna in the ear to collect and direct sound waves.
5.Dicondylic skull with two occipital condyles.
6. A secondary palate separates the nasal passage buccalcavity .
7. The auditory capsule projects outwards as a swollen structure the tympanic bulla,
8. Jaw suepemion is craniostylic. ‘
9. Lower jaw is fomed of a large dentary bone which articulates with squamosal bone.
10. Cervical l vertebrae are seven in numbeus.
ll. Cozaooidsmdpreeonwoidsoftlaepectoralgirdle
12. The limbs are pentadacyle type..
13. Teeth are thecodont (present in sockets), heterodont (with different  types of teeth like incisors, canines, premolars and molars) and diphyodont (presence milk teeth in young which is replaced  by permanent  teeth in adults ).

l4.Presence of muscular diaphragm beteen thorax and abdomen
18.Presencen of corpus callosum in the brain
19.presence of four optic lobes  in the brain.
20. Cochlea of theinner ear is highly coiled.
21- Three ear osszcles, namely malleus, incus and stapes are present in the middle ear.
22The copulatory Organ is the penis. The testes are extraabdominal in position and is in scrotum
23.Ovum develops in the Graafian follicle of the ovary.
24.They are viviparous and show high degree of parental care.
25.Presence of placenta for nutrition,respiration,excretion etc

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