BIOLOGY FOR CLASS IX

 Content  Vertebrata  Class Amphibia  Class Reptilia  Class Aves  Class Mammalia  Local Flora And Fauna Of Pakistan CHORDATA AND VERTEBRATA Class IX

 Vertebrates are the most organized organisms on Earth.  They belong to the sub-phylum Vertebrata.  They are not the most numerous group of animals, they are the most advanced group of animals.  The characteristics that makes vertebrates special are the presence of the spinal cords, vertebrae and notochords.

 Skin covered in scales  Ectothermic, cold blooded  Soft shelled eggs that must be laid in water  All members are fully aquatic  Limbs modified into fins  Gas exchange through gills

 What is vertebrate?  Write four characteristics of picis.

 The skin of amphibians is very thin and must always be kept wet because amphibians breathe through their skin.  They have lungs, but their lungs are small and are not used very much.  The eggs are covered with jelly to protect them.  They slowly change (metamorphose) into the adult amphibian which lives on land but always near water.

 Examples of amphibians are the frog and the newt.

 Latin repere or reptum means to creep or crawl, hence, the class name refers to locomotion that is of creeping or crawling mode.  These animals are mostly terrestrial and their body is covered dry and cornified skin, epidermal scales. External ear opening is absent, tympanum represents the ear. Limbs, if present are of two pairs.  Usually heart is three-chambered, but is four chambered in crocodiles. They are poilkilothermic(cold blooded) animals. Some animals like the snake and the lizards shed their skin. Sexes are separate, internal fertilization takes place.

 Reptiles live on land, although many of them swim well and may feed in water, such as some snakes and lizards.  They breathe using lungs.  The female lays soft-shelled eggs which are often buried in sand or in the earth to protect them while the young develop inside.

 Examples of reptiles are crocodiles, snakes and lizards.

 What do you know about amphibian?  Define class reptile.

 Most of the members can fly, except the flightless birds.  The characteristic feature of birds is the presence of feathers.  The forelimbs are modified as wings.  The hind limbs are modified for walking, swimming or clasping and generally have scales.  The skin is dry and does not have glands, except a oil gland at the base of the tail.  Endoskeleton is bony, and the bones are hollow with air cavities.  Heart is four-chambered completely. They are warm-blooded animals. Lungs are the organs of respiration. Sexes are separate.

 Example: Crow, Pigeon, Parrot etc.

 Mammals are present in almost all habitats - polar ice caps, deserts, mountains, forests, and grasslands.  The unique characteristic of the class mammalia is the presence of milk producing glands (mammary glands), by which the young ones are nourished.  The limbs are of two pairs. The skin is covered with hairs. External ear 'pinna' is present.  Heart is four-chambered and they are homeothermic animals.  Respiration is through lungs.  Sexes are separate.

 Example: Kangaroo, Tiger, Lion, Platypus etc

 Write 5 features of class aves.  What is the characteristics of class mammals?