Classification

We classify living organisms by their shared characteristcs.

Some characteristcis like feathers are unique to a group whilst others who have a backbone are common to several groups.

Animals with backbones are called vertebrates. There are 5 groups:

Fish- excahnge oxygen and carbon dioxide across gills and lay eggs that are ferilised internally.

Amphibians- Exchange gases through their skin and lay externally fertislised eggs. 

Reptiles- exchange gases via their lungs and lay internally fertilised eggs.  

Birds- *

Mammals- give birth to live young which grow inside the body of the mother. Eggs are fertilised…