CBSE Class 9 Answered

Pisces

Exclusively aquatic animals

1. Organisms belonging to class pisces are fishes.

2. Fishes respire through their gills and obtain oxygen dissolved in water.

3. They are 'cold-blooded' or 'poikilothermal animals'.

4. Skin of fishes is rough and covered with scales/plates which form the exoskeleton. The scales provide protection to the fishes.

5. They do not have limbs for locomotion, but have paired or unpaired fins with the help of which, they move in water. They also help in balancing.

6. Two main types of fishes, cartilaginous and bony fishes.

7. Cartilaginous fishes have skeleton made of cartilage. Their gill-slits are exposed without a gill-cover.

8. Bony fishes have skeleton mane of bones. Their gill-slits are concealed under a gill-cover.

Cartilaginous fishes: Shark, dogfish, Skate

Bony fishes: Carp, Roach, Herring, Trout

Amphibia

Partly live on land and partly in water

1. Body is divisible into head and trunk. Neck is absent

2. Have short forelimbs and long hind limbs with five webbed digits

3. Respiration in early stages of life as larvae is by means of gills, while adult amphibians breathe by means of lungs.

4. Lack of scales on their body. The body is smooth.

5. The eardrum or the tympanum lies on the surface of the skin.

6. They are pentadactyl with five fingered limbs.

7. Have a three-chambered heart with two auricles and one ventricle.

8. Cold-blooded vertebrate animals

Frog, Toad, Salamander, Newt

Reptilia

Terrestrial as well as aquatic

1. Body is covered with dry water-proof skin having horny epidermal scales or dermal scute plates

2. Body is divisible into head, neck, abdomen and tail.

3. The skin is dry, rough and has horny scales on it.

4. Cold-blooded, have scales and breathe through lungs right from birth.

5. Pentadactyl animals

6. Respire only with lungs

7. Eggs have a tough leathery shell

8. Most of them have a three chambered heart. Ventricle of the heart is partially divided.

9. The eardrum or the tympanum lies at the bottom of a tubular depression.

Lizard, Snake, Tortoise, Turtle, Crocodile, Alligator

Aves

Mostly aerial

1. All birds belong to class aves

2. Warm blooded or homeothermal animals

3. Heart is four chambered.

4. Body is covered with feathers. They have wings to fly. Two forelimbs of birds are modified into wings.

5. Mouth is modified into a beak.

6. Have scales only on legs

7. Respire through lungs

8. Body is streamlined

9. Lay eggs with calcareous shells

Pigeon, Sparrow, Crow, Duck, Owl, Penguin, Ostrich, Emu

Mammalia

Terrestrial, aerial as well as aquatic

1. Directly give birth to living young ones

2.  They suckle young ones by means of mammary glands.

3.  Have hair on their skin as well as sweat and oil glands.

4.  Warm blooded animals

5.  Have four chambered heart with two auricles and two

ventricles.

6.  Have a muscular diaphragm separating the thorax and

abdomen internally.

7.  Breathe by means of lungs

8.  As a rule, they have a pair of external ears or pinnae and external testes contained in a scrotum (testicles).

Cat, Dog, Cow, Sheep, Rat, Bat, seal, Monkey, Apes, Man