CLASSIFICATION OF ANIMALS
There are billions of different kinds of living things on Earth. These organisms have been classified into five kingdoms by into classes to make it easier to study them. Animal Kingdom comprises organisms that are BAC Whittaker. Scientists have grouped animals.multicellular and have heterotrophic mode of nutrition. They can be split up into main groups, vertebrates (with a backbone) and invertebrates (without a backbone).
Vertebrates
Animals with a backbone are called vertebrates. These animals are divided into five groups.
1. Class Pisces (fishes)
2. Class Amphibia (Live both land and water)
3. Class Reptilia (ஊர்வன).
4. Class Aves (avis meaning 'bird')
5. Class Mammalia (mamma meaning Mammary or milk gland')
Class Pisces
These are aquatic animals.Their body is covered with scales and they also have fins.Pisces are cold-blooded animals.They have a streamlined body which helps them swim in water easily.They breathe dissolved oxygen through special organs called gills.
Some examples of pisces are stingray, trout, electric ray, rohu, dogfish and catla.
Class Amphibia
They are the vertebrates adapted to live on land as well as in water.They are cold-blooded animals.Most amphibians · They do not lay their eggs in water. They have webbed-feet and their body is covered with moist, slimy and slippery skin.They breathe through the lungs and skin.
Class Reptilia
They are the creeping or crawling vertebrates. Reptiles are mostly terrestrial animals. But some reptiles live in water too. They are cold blooded animals.They have dry,cornified skin without skin glands.Reptiles breathe through lungs.They lay eggs on land.
Some examples are lizard, tortoise, turtle, snake Some examples of amphibians are frog, toad and crocodile, and salamander,
Class Aves (Birds)
Their body is covered with feathers. They are animals with wings and are adapted forflightTheir jaws are modified into beaks.They breathe through the lungs.They are warm-blooded animals.Their bones are hollow and help them to keep their body light.They lay eggs with hard shells.Their forelimbs are modified into wings.They bear scales only on legs. They have claws on their toes.
Class Mammalia (Milk-nourishing animals)
Mammals are mostly terrestrial. Their body is covered with hair or fur.These animals feed their young ones with milk as they have mammary glands.They are warm-blooded animals.Most of them give birth to young ones.They have a four-chambered heart.They breathe through the lungs.They usually have four limbs and some of them have a tail too.
Some examples of mammals are platypus, kangaroo, camel, monkey, human beings, lion, dog and cat.
QUICK NOTES
on the basis of presence or absence of backbone, animals can be divided into vertebrates invertebrates
Vertebrates are categorised into five classes.
Pisces are cold-blooded aquatic animals with streamlined bodies andTheybreathe through gills
Amphibians are cold blooded animals that can live on land and in water
Reptiles are cold blooded animals that breathe through the lungs and lay eggs. Aves are warm-blooded animals that have feathers and most of them can fly They lay eggs.
Mammals are warm-blooded animals that give birth to babies and suckle them with milk.
Invertebrates are categorised into different classes. * Porifera are simple, multicellular organisms with pores all over their body.
* Coelenterata are animals with tentacles that have stinging cells called cnidoblast. * Platyhelminthes are flat, unsegmented worms. Nematoda are round unsegmented worms.
* Annelida has a cylindrical, segmented body.
* Arthropoda has animals with three pairs of jointed legs, and body divided into thorax and abdomen. * Mollusca has animals with soft, unsegmented bodies and a hard shell. Echinodermata has marine animals with radially symmetrical body and sharp spines.
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