Amanda is a retired educator with many years of experience teaching children of all ages and abilities in a wide range of contexts.
What Are Amphibians?
Amphibians are cold-blooded animals that are able to live both in water and on land. Most start life with gills, but later develop lungs for breathing.
Frogs, toads, salamanders, newts and caecilians are all types of amphibian. They are cold-blooded creatures that rely on their surroundings for warmth, and are found in most parts of the world. Adult amphibians usually have soft, thin, moist skin that absorbs oxygen from the air, helping them to breathe. But some frogs and toads have thick, warty skin to help them survive in drier conditions.
The way amphibians breed and develop is unique in the animal kingdom. Females lay their jelly covered eggs, called spawn, in water. These hatch into tadpoles, which develop limbs and lungs so that they can live on dry land. Some amphibians need only a small amount of water in which to lay their eggs. The tree frog lays its eggs on moist leaves and the male midwife toad carries the female’s eggs on its back legs, dipping them in pools of water. The Australian gastric brooding frog swallows her eggs. Once they have developed into froglets, they hop out of her mouth.
All amphibians are hunters. Many use their bulging eyes to track fast moving prey, swallowing it whole. Small frogs and salamanders eat insects and tiny fish. Large toads gulp down mice and birds. They usually sit and wait, or crawl towards their prey, before lunging with mouth open. Some frogs and salamanders have a long, sticky-tipped tongue attached to the front of their mouth, which they cab flick out to grab insects.
Leaping Frogs and Creeping Toads
Over 80% of all amphibians are frogs and toads, known as anurans. They have long, five-toed back legs for leaping and shorter, four-toed front legs used to cushion the landing. There is no scientific difference between frogs and toads, but anurans with smooth, moist skin that usually jump are called frogs, and those that waddle and have drier, lumpy skin are called toads.
Salamanders and Caecilians
Newts and salamanders (urudelans) have short limbs and long tails. Salamanders in Europe and North America that spend long periods in water are called newts. Most salamanders breathe with lungs and through their skin, although some have no lungs. Caecilians (apodans) are the third and smallest group of amphibians. They are wormlike, with blunt snouts for tunneling, tiny eyes, and wide mouths. They hunt mainly at night.
The Amphibian Life Cycle
When frogs mate, the male usually sits on the female’s back for up to three days. As soon as the female lays her eggs in the water, the male releases sperm to fertilize them. The eggs hatch into tadpoles, which eventually metamorphose (change) into froglets (young frogs) and leave the water for life on land.
The female frog lays her eggs, or spawn, in large masses in a pond or stream. The eggs are protected by a special jelly.
The lavae, or tadpoles, develop inside the eggs. About a week later, the tadpoles hatch out and attach themselves to plants.
The tadpoles breathe through their feathery gills and start to swim at about three days old. They feed on water weeds and algae in the water.
The tadpoles slowly turn into frogs, developing limbs and lungs so that they can live on land. Their tails are absorbed into their bodies.
Fully grown, the young frogs leave the water. They feed on small insects and will not reproduce themselves until they are a year old.
Life Cycle of a Frog
The Poisonous Fire Salamander
When the fire salamander is attacked by a predator, poison oozes out of the pores in its skin. It has two special glands that hold its poison. They can be found across its back and on the sides of its head. All amphibians have glands in their skin that produce slime to help keep it moist. Some also create foul tasting or poisonous substances as a defense against predators. The fire salamander’s bright markings warn predators that it is poisonous to eat.
More Facts About Frogs and Toads
As we’ve seen, frogs and toads belong to the group of animals known as amphibians. Most spend their early life as tadpoles in water, but the adults live mainly on land.
Frogs, while related to toads, generally have slimmer bodies with a smooth skin, while toads have a drier warty skin. All amphibians have thin skin as their lungs are inefficient and they use their skin to breathe through. Oxygen from the air passes through the skin into tiny blood vessels just under the surface. This can happen only if the skin is moist, so frogs and toads are usually found in damp places.
Most frogs feed on slugs, insects and worms, which they catch with a long, sticky tongue. Larger frogs, such as the American bullfrog, also feed on prey such as mice, and even small ducklings.
Frogs are great jumpers. Their long, muscle-packed hind legs can send them shooting over 12 times their own length through the air. Webbed feet help frogs swim, while tree frogs make huge leaps from branch to branch, aided by sticky pads on their toes. Toads have less powerful back legs than most frogs and waddle.
Green or brown is the typical color of most frogs, but some tropical frogs are brilliantly colored. Some species change their skin color with changes in light or temperature, and all frogs shed the outer layer of their skin several times a year, pulling it over their head with their legs.
Frogs and toads can be very noisy at breeding time, when males croak to attract females. The European Marsh frog is one of the noisiest. A colony sounds like a crowd of people laughing.
Sources and Resources
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2020 Amanda Littlejohn
Amanda Littlejohn (author) on December 22, 2020:
Alnajda Kadi from Tirana Albania on December 22, 2020:
What an interesting article!
Amanda Littlejohn (author) on December 21, 2020:
Thank you Pamela! yes, wise to keep a good distance from those!
Pamela Oglesby from Sunny Florida on December 18, 2020:
This is a very interesting article, Amanda. The poisonous salamander has interesting markings, but I wouldn't get too close.