- Reptiles are completely live on land. They lay eggs on land. Their skin is hard and rough. Snake, crocodile and turtle are the example of reptiles.
- The body of birds is covered with feathers. Birds can fly easily with the help of their strong wings. Sparrow, eagle, parrot and pigeon are the example of birds.
- Mammals give birth to young once and the mother feeds the babies with her milk. They have hairs on their bodies. Cow, goat and buffalo are the example of mammals.
- Human beings are also mammals.
- Dolphin and blue whale are marine mammals.
- Bat is a unique mammal that can fly in air.
- Ostrich is the largest birds of the world.
- Invertebrates are those organisms which do not have back-bone in their body.
- Examples of invertebrate are housefly, mosquito, honeybee, ant, cockroach and butterfly.
- Major groups of invertebrates are sponges, worm, insect, molluscs and echinoderm.
- Snail, oyster and octopus are the examples of mollusks.
- Sponges are aquatic animals and live in ocean mostly.
- The body of sponges is full of pores externally and canals internally.