1. Vertebrates or Invertebrates
We divide the animal Kingdom into two groups:
Vertebrates are animals with a backbone inside their bodies.
Fish, dogs and humans are examples of vertebrates.

2. Vertebrates or Invertebrates
Invertebrates do not have a skeleton. Some examples of these are spiders, flies and caterpillars.
Vertebrates are often larger and have more complex bodies than invertebrates. However, there are many more invertebrates than vertebrates.

3. Vertebrates
Cold-blooded vertebrates depend on their surroundings to keep their body temperature. When there is no sun, and the air is cold, the animal gets cold. When it is sunny and hot, the animal gets hot, and generally more active.

4. Vertebrates
Warm-blooded vertebrates are types of animals that regulate their own body temperature and they normally have layers of fat, feathers or fur. Mammals and birds are warm-blooded.

5. Vertebrate classes Class Main features Examples amphibians
moist permeable skin
frog, newt, salamander
fish
gills, wet scales
goldfish, shark, cod
reptiles
dry scales
crocodile, lizard, snake
birds
feathers, beaks
budgerigar, sparrow, ostrich
mammals
fur, produce milk
rabbit, kangaroo, human, dolphin

6. Fish Fish breathe through gills, and live in water.
They have scales and fins.
Most are cold-blooded and lay eggs (sharks are fish, but they give birth to live young).

7. Amphibians
Amphibians are cold-blooded and live in water as tadpoles (breathing through gills) and on land as adults (breathing with lungs).
The main types of amphibians are frogs and toads, and salamanders.

8. Reptiles
Reptiles are cold-blooded and breathe with lungs. They have scales, and most lay eggs.
Reptiles include snakes, turtles and tortoises, crocodiles and alligators, and lizards.
Dinosaurs were reptiles, although some scientists believe that some were warm blooded.
Reptiles are more common in the tropics than in warm regions and are not found in polar areas.

9. Birds Birds are warm-blooded animals with feathers and wings.
They lay eggs, and most
can fly (although many, including penguins and ostriches, can’t fly).
Because birds are warm-blooded, their eggs have to be incubated to keep the embryos inside warm, or they will perish.

10. Mammals
Mammals are warm-blooded, and are nourished by their mothers’ milk; most are born live (however, the platypus lays eggs).
Most mammals also have body hair.
We, humans, are mammals too.