20 frog facts
You probably learned the frog lifecycle at school. Here are some facts your teacher won’t have mentioned
1. Some tropical frogs are absolutely lethal
Poison dart frogs are the most poisonous vertebrates in the world. Their name comes from the use of their poison by South American hunters to lace the tips of blow darts. The toxin secreted from the skin of the 5.5-centimetre (2.2-inch) golden poison dart frog is strong enough to kill ten men.
2. Males make themselves heard
Male frogs croak and call to attract females and let other males know that they’ve claimed a territory. The calls show off how healthy potential suitors are, and some are so loud they can be heard 1.6 kilometres (one mile) away.
3. You won’t see many frogs in winter
Frogs can escape the cold of winter by hibernating underwater or burrowing into the soil. While they sleep, a new layer of growth forms on their bones, creating age rings similar to the ones found in trees. Some species, like the wood frogs, hide among leaf litter and let their bodies freeze. Their hearts stop beating, their blood stops flowing and up to 65 per cent of the water in their body freezes, but come spring they thaw and hop off.
5. Not all frogs hop – some walk and run, and waxy tree frogs grip branches with opposable toes and move like chameleons.
6. The world’s largest frog is the Goliath frog. It can grow to 32 centimetres (12.6 inches) in length and weigh as much as a newborn baby.
7. Frogs don’t drink through their mouths; they absorb the water they need through their permeable skin. Many have an extra thin patch on their underside known as a drinking patch.
8. Toads are frogs. They all belong to the order Anura – toads are just frogs with short legs and dry, bumpy skin.
4. Amphibians have existed for around 395 million years, and frogs first hopped onto the scene around 190 million years ago.
9. The Egyptians had a frog goddess
Frogs were considered symbols of fertility in ancient Egypt, as they were associated with the yearly flooding of the Nile. Heqet, the goddess of fertility and childbirth, was usually depicted as a frog or a frogheaded woman.
10. Frogs swallow with their eyes
With their round, bulging eyes, frogs can see in almost every direction at once.
They also have an extra eyelid. Known as a nictitating membrane, it is semitransparent and both lubricates the eye and protects it underwater. When a frog is swallowing a particularly large piece of food it will blink hard, forcing its eyes back into its head to help push the food down.
11. Frogs can’t chew their food
While our tongues are attached to the back of our throat, a frog’s tongue begins at the front of its mouth. This allows the frog to throw its sticky tongue out as far as possible when it’s hunting insects. Lacking teeth suitable for chewing, everything it catches is swallowed whole. 13. Tadpoles are wary Some tree frogs lay their eggs on leaves above rivers and streams. If the tadpoles sense danger, they can quickly wiggle out and drop into the water.
18. There are around 4,740 species of frog known to science, living in habitats ranging from ponds and lakes to trees and grasslands. 19. Male Darwin’s frogs take their paternal duties seriously
A female Darwin’s frog lays around 40 eggs in leaf litter before the father takes up position as guard. When the growing young begin to move, the male ingests the eggs so they can go through the remaining stages of development in the safety of his vocal sac. Two months later, small frogs hop out of his mouth and set off into the forest. 12. Some frogs are see-through Glass frogs live up to their name. These little tree frogs have transparent skin, leaving all their internal organs on show.
14. The round patches of skin located on a frog’s
head just behind the eyes are the tympanums. These non-glandular skin membranes transmit sound waves from the air to the
frog’s inner ear.
15. The Bornean flatheaded frog is the first frog discovered to have no lungs. Rather than breathing, it takes in all the oxygen it needs through its skin.
16. In medieval times frogs were considered to be signs of the devil and accomplices of witches. These superstitions might have arisen from the warty skin of toads and the toxic secretions they produce to
ward off predators.
17. Many frogs can use their strong legs to cover more than 20 times their own body
length in a single jump.
20. Frogs will eat their own skin
Frogs periodically moult to fend off infections and keep their bodies in good condition. Rather than wasting it, they’ll eat the shed skin to regain some of the nutrients. In some species the skin is covered with mucous or a waxy coating to trap moisture.