What is a Mammal?

All mammals, from bats to whales, share a number of important traits that make them different from other creatures. For one thing, mammals spend much more time raising and training their young than other animals do.

Almost all mammals give birth to live young, rather than laying eggs, as birds do. Female mammals are the only creatures on earth that make milk for their young. The milk is rich in vitamins, minerals, and all the other nutrients a young animal needs.

Unlike the cold-blooded reptiles, which often need to lie in the morning sun to warm up, the warm-blooded mammals are always ready to go. Their bodies make enough heat to stay at the same temperature and work right at all times.

Scientists believe that large marine mammals like whales and dolphins have brains much like those of humans. They are able to communicate, follow instructions, and figure things out.

What is a Reptile?

Today there are 6,800 reptile species on earth; the major groups are alligators and crocodiles, turtles, lizards, and snakes. All reptiles are cold-blooded, which is why they warm themselves in the sun, and have bodies covered in dry, horny scales. Some reptiles lay eggs; others give birth to live young.

What is a Bird?

Birds are warm-blooded creatures, like mammals, but they lay eggs, like most reptiles. All birds have feathers and wings, and most birds are able to fly. Birds are amazingly varied in their shapes, sizes, colors, and behavior patterns. There are more than 9,000 different species of birds in the world.

What is an Amphibian?

Like birds, reptiles, mammals, and fishes, amphibians are vertebrates –- that is, creatures with a backbone and an internal skeleton. Amphibians live part of their life in water and part on land. Even those species that lay eggs on land start life in a fluid-filled egg, breathing through gills.
 

What is a Fish?

Fishes come in an amazing variety of shapes and colors, but they all have three important things in common: All fishes live in water, have fins, and use gills to get oxygen from the water. We have also included a few sea creatures -- some jellyfish and octopods -- in this category.

What is an Insect?

Insects and their relatives, including spiders and scorpions, belong to a huge group of animals called the arthropods. The main thing that all arthropods have in common is their hard outer coat, which is called an exoskeleton and protects their soft insides. The bodies of arthropods are divided into sections.  Nearly 100,000 insect species live in North America. Scientists group these species into orders. Many of the insects you are most likely see belong to twelve orders. You will also probably come across other insects and some non-insect creatures such as spiders, mites, scorpions, and centipedes.