A mammal is a kind of animals.  Dolphins, horses, and cats are mammals.  mammals have fur, give birth to their young, feed their young with their milk, and are warm blooded.

A bird is a kind of animal.  Birds have feathers, lay eggs, and are warm blooded.

A reptile is a kind of animal.  Reptiles have scales, lay eggs, and are cold blooded.

A fish is a kind of animal.  Fish have scales, lay eggs, breathe through gills, swim, and are cold blooded.

A frog is an amphibian.  An amphibian is a kind of animal.  Frogs are cold blooded and lay eggs.  Amphibians can live on land and water!

An insect is a kind of animal.  An insect has a hard exterior.  Insects lay eggs.  Insects have 6 legs.  Ants, butterflies and bees are insects!

An invertebrate is a kind of animal.  Invertebrates are soft, they do not have a skeleton.  A worm is an invertebrate.