These amphibians are known as dart frogs because indigenous people use the frog’s poison for blow darts and arrow poison. All wild dart frogs secrete toxins through their skin. However, captive-hatched frogs and wild ones that have been in captivity for an extended time are not toxic. Color shades vary among frogs within a species. It is the skin that contains the frog's poison. These beautiful colors are warnings to potential predators that the frog are poisonous. Several species of non-poisonous frogs evolved with similar coloring to avoid being eaten.