What Are Mammals

Mammals are a group of animals that share three major traits. These traits help children understand how animals are sorted in nature and allow them to identify mammals in simple, observable ways.

Are bears mammals?

The first trait is that all mammals are warm-blooded. This means they can keep their body temperature steady, even when the environment changes. A squirrel in winter or a whale in cold water stays warm because its body regulates heat on its own. This is different from reptiles or amphibians, which rely on outside temperatures to warm up or cool down.

The second trait is that mammals have hair or fur at some point in their lives. It might be thick fur on a bear, a light layer on a dolphin, or the hair on a human head. Hair and fur help mammals stay warm and sometimes help them blend into their environment.

The third key trait is that mammals feed their babies milk. This is one of the most important clues when identifying a mammal. Even though mammals come in many shapes and sizes, from tiny mice to enormous blue whales, they all nurse their young.

Helping children compare mammals to other animal groups strengthens their understanding. Birds have feathers and lay eggs. Fish have scales and live fully underwater. Reptiles lay leathery eggs and depend on warmth from their surroundings. When children see the differences clearly, they can spot mammals easily on nature walks, in parks, or at home with pets.

In our related episode, we show real examples, model comparisons and offer activity sheets that reinforce early science concepts like classification and observation.

These materials support Grade 2 and younger by breaking down science into clear, manageable ideas.

Check out our recent episode on this topic for simple activities, visuals and mammal-focused learning.