5. FISH

Those are the characteristics used to define the fish class:

1. They might be herbivorous, carnivorous or omnivorous. They can eat other fish, invertebrates, algae or seaweeds.

2. They are oviparous, it means that they lay eggs, and those legs must not be incubated, but sometimes the eggs are protected by their parents. Some fish can be ovoviviparous.

3. Offspring are usually independent when they are born.

4. They are cold-blooded and breathe through gills.

5. Birds are covered by scales and have fins to move.

6. They live only inside of the water: cold (goldfish), warm, salt or fresh; but some species have developed lungs-like and might spend a little time out of the water.

7. Scientists differ about the number of species. They are estimated from 194,696 to 214,696. Some species are very old like some sharks or Coelacanths.