Classes of Animals

Mammals

  • warm-blooded
  • born alive and with fur or hair
  • breathe air through lungs
  • vertebrate (has backbone) and four limbs
  • examples: bears, dolphins, tigers, and people

Birds

  • warm-blooded
  • has feathers, two legs, and two wings
  • vertebrate (has backbone)
  • lay eggs and their young hatch from the eggs
  • examples: tiny hummingbird and large ostrich

Fishes

  • cold-blooded
  • vertebrate (has backbone)
  • lives in water with scales and fins and breathes through gills
  • lay eggs and their young hatch from the eggs
  • examples: salmon, puffer fish, and gold fish

Reptiles


  • cold-blooded
  • has short legs or no legs with dry scaly skin
  • vertebrate (has backbone)
  • born on land and breathe through their lungs
  • examples: snakes, turtles, and liquids

Amphibians

  • cold-blooded
  • lays their eggs in the water
  • spends part of their lives under water and land
  • breathes with gills or lungs or through their skin
  • vertebrate (has backbone) and skin is moist and doesn't have scales
  • examples: frogs, newts, and salamanders.

Invertebrates

  • cold-blooded
  • doesn't have backbone has external skeleton
  • segmented body and has many jointed limbs
  • 85% of animals are invertebrates
  • most common examples: protozoa, mollusks, and arthropods