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Friday, April 27, 2007

Thursday, April 26, 2007

Tuesday, April 24, 2007

Vertebrates

Vertebrates

1. Vertebrates are animals with backbones.
2. Warm-blooded vertebrates ( homoiothermic ) have fixed body temperatures, cold-blooded vertebrates ( poikilothermic ) have body temperatures that change according to the temperature of their surroundings.
3. Vertebrates can be divided into five main groups, which are fish, amphibians, reptiles, birds and mammals as shown below :

System of classification of animals

Animals can be classified into two groups :
(a) Invertebrates ( animals without back-bones )
(b) Vertebrates ( animals with backbones )

Invertebrates

1. Invertebrates are animals which do not have backbones.
2. Invertebrates make up the most number of animals in the world.
3. Most invertebrates live in the water.
4. Some invertebrates have a hard external skeleton for protection like the crab and the beetle.
5. Some invertebrates have soft bodies using their body fluids for support like the earthworms and leeches.
6. Generally, invertebrates can be classified into two groups, that is
(a) with jointed legs
(b) without jointed legs