The tree frog is any species of small frog that spends the majority of its life living in trees. There are numerous types of tree frogs. Usually tree frogs do not leave their trees unless mating or spine, and some even do not do this. They can even build foam nests in trees to spawn their offspring. The backs of tree frogs are usually a bright green, with other parts of their bodies being other colors including orange and yellow. Tree frogs can even change the color of their skin to help them blend in with their surroundings or to warn predators of their deadly poisons. The poison residing in their skin is sometimes used by primitive people to tip blow gun darts and arrows for the purposes of hunting and war. While tree frogs are sometimes advertised as being for sale, this is generally not considered wise as many species are deadly poisonous.