Some even have square or heart shaped pupils. A frog's skin reflects the same amount of ultraviolet light as its immediate surroundings. This way it can protect itself from predators like snakes. The golden dart frog is the most poisonous frog on earth and the skin of one frog could kill up to 1,000 people. In recent years, a painkiller with 200 times the power of morphine has been found in the skin of a frog.
Some frogs can survive in conditions well below freezing.
The Grey Tree Frog. It does this by making its own antifreeze, which stops its body from freezing completely. The male Darwins Frog takes its mate's eggs into its mouth as soon as they show signs of life and they stay there until they emerge as fully grown froglets. Frogs cannot live in the sea or any salt water. Many of the most brightly colored tropical frogs are colored in this way to warn predators that they are poisonous.