Almost all animals fall into one of two groups.
Vertebrates are often larger and have more complex bodies than invertebrates.
However, there are many more invertebrates than vertebrates. Cold-blooded animals depend on their surroundings to establish their body temperatures. Three types of amphibians are frogs and toads, salamanders, and caecilians. Caecilians are primitive amphibians that resemble earthworms. They are found in the tropics.