Frogs also differ in color. Most kinds are green or brown, but some have colorful markings. Although different species may vary in size or color, almost all frogs have the same basic body structure. They have large hind legs, short front legs, and a flat head and body with no neck. Adult frogs have no tail, though one North American species has a short, taillike structure.
Most frogs have a sticky tongue attached to the front part of the mouth.
They can rapidly flip out the tongue to capture prey. Like higher animals, frogs have such internal organs as a heart, liver, lungs, and kidneys. However, some of the internal organs differ from those of higher animals. For example, a frog's heart has three chambers instead of four. And although adult frogs breathe by means of lungs, they also breathe through their skin.