Frogs and toads begin life as gilled tadpoles that develop in water after hatching from eggs. These tadpoles undergo a process called metamorphosis during which every aspect of their biology changes. Gills turn into air-breathing lungs, jaws reform, even the digestive track changes as vegetarian tadpoles transform into carnivorous adults. When full-grown, frogs retain permeable skin, making it necessary for all but a few species to live close to water.
The adult frogs are built for leaping. Unlike other amphibians, they have lost their tail and evolved long, sturdy hind legs. Frogs also have the ability to vocalize. Male frogs fill vocal sacs beneath their jaw with air to emit distinctive mating calls or to sound a warming when predators approach. Each species has its own distinctive call.
While there are many differences between the two, all toads are frogs. Visually, frogs tend to be long and skinny while toads are short and stubby. Frogs’ skin is frequently smooth while toads are often rough and warty. Finally, toads are skilled at using their long tongue to catch insects in mid-air while frogs must leap to catch their prey.
All frogs and toads have special glands to produce poison. Such species are brightly colored to ward off predators. Very few species of poisonous frogs are toxic to humans.
Snakes are cold-blooded, carnivorous reptiles that evolved from lizards 150 million years ago. Their bodies are covered with scales that they shed once or twice a year. Snakes are distinct from lizards in that they lack legs, eyelids, and external ears.
Despite their lack of limbs, some snakes can climb trees, burrow underground, or swim in ponds and lakes. While burrowing snakes tend to eat insects and worms, the majority of snakes eat large prey that they capture and swallow whole. Venomous snakes, such as vipers and cobras, have evolved specialized glands and fangs that emit toxins to capture prey. Others, such as boas and pythons, will constrict and squeeze their prey.