Monday , 24 September 2018
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The colourful life of frogs

The colourful life of frogs

Maneka Sanjay Gandhi

While frog populations are disappearing, we discover new species just in time to see what magical creatures we are losing. Nothing makes me more excited than learning of the strange and wondrous creatures that we have on this planet.

What can you do if pellets from a shotgun stick in your chest, or you have a radio transmitter stuck in your side? They would have to be removed through surgery. But if you were a frog, your body would deal with it. Frogs have the remarkable ability to pee out foreign objects, with their bladders engulfing the intrusions. No other animal has ever used their bladder to eliminate foreign objects embedded in their bodies.

Scientists implanted temperature-sensitive radio transmitters in Australian tree frogs to learn about their temperature-regulating abilities. Unexpectedly, after 25 to 193 days, when the investigators recaptured the amphibians to recover the transmitters, many of the devices were no longer in the body. They had somehow migrated to the bladder. To confirm these bizarre results, the researchers implanted small beads into the body cavities of five Australian green tree frogs and five cane toads. The beads made it to the bladders and were expelled within 19 days on average

Frogs have soft bodies and they leap about thus sticks, thorns and other foreign objects often enter their thin skins. Their bladders can hold vast quantities of urine, sometimes even more than their body mass, and have evolved to help frogs take out the garbage.

Horned frogs of South America can eat prey much larger than their own bodies, thanks to the strength of their tongues. When frogs catapult their tongues to catch a creature, the organ’s adhesive forces exceed the weight of the animals’ prey. Lizards, snakes, rodents, spiders, insects and other frogs are lifted off the ground and pulled into its mouth. The force ranges from three to six times the frogs’ body weight and the operation takes less than 40 milliseconds. A frog’s tongue can snap back into its mouth within 15/100ths of a second.

Thailand’s Mulu flying frog uses its webbed feet to glide from tree to tree and feeds on birds. Its bright green skin at night changes colour to become brown during the day; so do its eyes.

Seeing birds on the backs of water buffaloes is common, but the ones in the wetlands of Turkey carry tiny frogs on their backs. The buffalo-riding marsh frogs forage on the buffaloes’ shaggy bodies for flies.

Tadpoles can regenerate their tails as late as 18 hours after amputation, even after a scar-like lesion has formed. This ability is lost as they turn into frogs.

The red eyed tree frog shakes his rear violently when he sees another male. The shaking becomes a whole-body affair, sending vibrations along the frog’s plant perch until it reaches the opponent on the branch. The other male responds in kind. Both frogs shake at a frequency of 12 hertz or 12 times a second. The one who shakes the longest gets the girl.

The Australian green tree frog gets water in the desert when there is none, with an innate understanding of science. Frogs move from the cool dry night air to warm burrows ‘fogging up’ like a pair of glasses, the droplets then condense on their skin. They do this repeatedly and thus their skin absorbs the water droplets and helps them survive the dry weather.

The male grey tree frog sounds a call to females, providing information about his gender, species, age, health and telling other males to stay away. If a female likes his call, she will approach him. When the male clambers onto her back she carries him to a water-body to lay her eggs, which the male fertilizes as they are being laid. Throughout this process they are accompanied by a sly, small, silent, satellite male who tries to get between the pair with the hope of dislodging the chosen male – and sometimes succeeds!

Males of the Indian dancing frogs, found in the Western Ghats, tap their hind feet and stretch one foot outward and shake it, both at prospective mates and rival males during the mating season. Their tadpoles live underground in sand in total darkness until they emerge as froglets. A layer of skin covers the tadpoles’ eyes, to protect them from abrasions. They have no teeth, though their jaws are sheathed with a serrated, gate-like structure that acts as a filter, keeping out large sand grains. They have ribs, which is extremely rare in tadpoles, which help them swim in sand. They feed by vacuuming up bits of decaying organic matter, which they digest with the help of another unusual adaptation: tiny spherical bags in their guts hold calcium carbonate or limestone to scrunch the sediment.

While all frogs produce a wide range of sounds, the Brazilian torrent frog has the largest vocabulary. It combines sounds and gestures, like squealing, head bobbing and alternate-arm waving. The conversation goes on all year (except October!) intensifying during breeding season. Males walk peculiarly, jump, wag their toes, stretch their legs, lift their arms, wave, shake their hands, jerk their bodies and inflate their vocal sacs alternately. Courtship includes this: Male frogs push off from the ground with their arms, to elevate the front parts of their bodies. They bob and wave their heads from side to side in snakelike figure-eight patterns. While sitting, they pick their feet up and show their toes. These gestures had never been observed in frogs before. The vocal playlist included peeps, squeals and a special courtship call made up of five notes. Males and females even shared special tactile signals, something else that was previously unknown in frog courtship. Males peeped courtship calls in response to a female’s touch.” Sounds just like human first love!

The emerald eyed Taiwanese frog survives by eating its mother’s gooey unfertilized eggs.

The Mount Iberia frog from Cuba currently holds the Guinness World Record for smallest frog at 10 millimetres long. But to make up for its size it is coated in poison. These dwarfs, downsized deliberately to prey on mites, are overlooked as meals by larger frogs. The mites possess alkaloids. By consuming them, the frogs reallocate their poisons for their own use.

Gardiner’s frogs, from the Seychelles islands, lack a middle ear and eardrum to hear sounds but use their mouth cavities to pick up on noise and make their own.

All frogs are known for their jumping skills. The Australian Rocket frog can leap over 50 times its own body length, 6.5 feet. The African frog is the best. It can jump 14 feet in a single bound.

The Bornean flat-headed frog is the world’s only lungless frog. It breathes through its skin.

Some South American frogs are so toxic that one drop of their skin secretions can kill a human. Poison frogs usually have bright colours to warn predators that their skin is toxic.

Amazon horned frogs are ambush predators and aggressively territorial.

Many frogs use their eyeballs to swallow. Once they have prey in their mouth, to help force it down their throat, they actually pull their eyeballs down to put more pressure on the food.

The African Clawed Frog has three claws on each hind foot, which it uses to tear food. Then it uses its hands to shove food in its mouth and push down its throat.

The common Surinam toad is one of the world’s most bizarre amphibians. The animal’s flattened shape makes it look like a pancake, and it spends its whole life in water. When the male and female mate, the female releases her eggs and the male catches and fertilizes them. The eggs embed in the spongy tissue of the female’s back, which grows over them. When the babies develop into froglets, they burst out of their mother’s back.

The tiny fingernail size ‘mutable rain frog’ of Ecuador’s Andes Mountains skips the tadpole stage and develops into a frog directly within its egg. It has a spiny skin texture which it can transform into smooth in minutes! Researchers also don’t yet know how the frog morphs its skin from smooth to spiny, and then back again.

Frogs do not adapt. Air temperature, wind, soil erosion, humidity – any change contributes to their disappearance. As they go, the world’s insect population – especially the pests increase.

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