Do you know how scientists classify the animal kingdom? Well they classify the animal kingdom into categories based on their characteristics. The two biggest categories are Vertebrates and Invertebrates.

Vertebrates have a backbone such as reptiles, amphibians, birds fish and mammals. Humans are mammals too because they have a backbone, warm blooded and when they are young their mothers feed them milk.

Invertebrates have no backbone. They make up 97% of the animal kingdom and are comprised of 7 groups. Arthropods-exoskeleton, annelida- worms and mollusc's there soft bodied Invertebrates, like snails and slugs. That’s three groups.