Australia is about to embark on a massive annual cane toad killing spree — known as the Great Cane Toad Bust — to put a dent in the numbers of this invasive pest. Now, scientists are proposing a humane method to purge the toxic toads.

Instead of bludgeoning cane toads (Rhinella marina, formerly Bufo marinus) with cricket bats and golf clubs, or poisoning them with harsh chemicals, scientists advise bagging the toads and sticking them in the fridge. The cold puts the amphibians into a state of torpor and shuts their pain receptors off. People can then transfer the toads to the freezer to finish them off humanely, said Rick Shine, a professor of biology at Macquarie University in Sydney, Australia.

"As a toad cools, its metabolism slows down and it becomes very inactive," Shine told Live Science in an email. "Even its brain shuts down. So a cold toad doesn't feel pain, and the toad never knows what is going on — it just falls asleep and never wakes up."

Cane toads naturally experience temperatures dropping at night, so their bodies don't go into shock when they are initially put in the fridge, Shine said. In a 2015 study, Shine and his colleagues found that the toad's brain activity declined smoothly during freezing and produced no detectable pain signals. By the time ice crystals start to form in a toad's tissues, "it's not aware of anything," he said.

Scientists introduced cane toads from Hawaii to Queensland, Australia, in 1935 to exterminate cane beetles (Dermolepida albohirtum) that were ravaging newly planted sugarcane crops. However, this effort backfired, because cane toads showed no interest in the beetles and multiplied uncontrollably. The toads, which secrete venom that can kill animals that eat them, spread to coastal New South Wales, the Northern Territory and parts of northwestern Australia. Everywhere they went, they triggered declines in native predators and caused damage to ecosystems.

Related: 'Monster cane toad' dubbed 'Toadzilla' found in Australia

Cane toads still wreak havoc today, prompting the environmental non-profit Watergum to organize the Great Cane Toad Bust, an annual campaign to kill as many toads as possible in a week. This year's kill-athon — the third nationwide bust and the first to target tadpoles as well as adult toads — will take place between Jan. 13 and Jan. 21.

"The Great Cane Toad Bust is Australia's biggest toad bust," Nikki Tomsett, Watergum's invasive species project officer, told Live Science in an email. "It's all about taking collective action to effectively and humanely control cane toads, which are an invasive pest species in Australia." 

The campaign has been successful so far, with people removing over 50,000 cane toads from their local environment in a single week, Tomsett said. "This year we're aiming to beat that record," she said.

Cane toads can live for more than 10 years in the wild, Tomsett said. Female toads produce as many as 35,000 eggs every time they breed, which means every toad matters when it comes to toad busting.

The cool-and-freeze method "is currently considered best practice for the humane euthanasia of cane toads," Tomsett said. "Blunt force trauma and most chemical applications are not considered humane, and pose a threat to wildlife and pets, as cane toads euthanized in this way are typically left in the environment and are still toxic after death."

People who club the toads to death also risk hitting the poison glands, which can cause temporary blindness in humans if it gets into the eyes," ABC News reported.

Australians are encouraged to keep busting cane toads after Jan. 21, Tomsett added.

A jumbo-size cane toad (Rhinella marina) captured in Queensland, Australia, has tipped the scales at a whopping 6 pounds (2.7 kilograms), earning it the nickname "Toadzilla" and likely making it the largest example of the species on record.

Rangers stumbled upon the hefty amphibian on Jan. 19 in Conway National Park while they were conducting track work. They announced their discovery via a tweet, writing that they were "shocked to find a monster cane toad" that weighed as much as a rooster.

"I just couldn't believe it to be honest — I've never seen anything so big," Kylee Gray, a ranger for the Queensland Department of Environment and Science, told the Australian Broadcasting Corporation (ABC). "It flinched when I walked up to it and I yelled out to my supervisor to show him. [It looked] almost like a football with legs."

Related: What's the difference between a frog and a toad?

Gray described the find as "a big warty, brown, ugly cane toad just sitting in the dirt," and she and her colleagues think it was a female, "due to the size, and female cane toads do grow bigger than males."

The official largest known toad on record is a cane toad (also called a marine toad) found in 1991, also in Australia, that weighed 5 pounds, 13 ounces (2.65 kg), according to Guinness World Records. 

After weighing the portly toad found at the national park, rangers euthanized it "due to the environmental damage they cause," they wrote in the tweet.

"A cane toad that size will eat anything it can fit into its mouth," Gray told ABC, "and that includes insects, reptiles and small mammals."

CNN reported that the toad's remains have been sent to the Queensland Museum for further analysis.

Frogs and toads make up the largest group of amphibians. Species in this order, called Anura, substantially outnumber those in the two other living orders of amphibians — Caudata (salamanders) and Gymnophiona (caecilians). As of August 2022, Anura had 7,486 of the 8,478 known amphibian species, according to Amphibian Species of the World, a reference website from the American Museum of Natural History in New York. 

Frogs and toads are among the most diverse animal groups. Though they might be most famous for their croaking and jumping, these animals have a wide variety of unique traits and behaviors. Like many other animals, frogs and toads are suffering greatly from human-related threats, and many species face imminent extinction. 

Frogs vs. toads

"Frog" and "toad" are common names that don't mean much from a scientific perspective. "Frog" can be thought of as the more encompassing word as it's the common name for the Anura order, and used in the common names of most of Anura's species. "Toad" is used more selectively in the common names of certain species or groups.

Amphibians with "toad" in their common names often have characteristics that are not typically thought of as frog-like. For example, "toads" usually live in drier habitats — and have drier, bumpier skin and shorter hindlimbs — than is typical for frogs, according to the Burke Museum in Seattle. However, all toads can be called frogs. 

Related: What's the difference between a frog and a toad?

Types of frog

Frogs come in a variety of shapes, colors and sizes. The largest frogs are Goliath frogs (Conraua goliath) from Cameroon and Equatorial Guinea; they can grow to be more than 1.1 feet (34 centimeters) long and weigh 7.3 pounds (3.3 kilograms), according to a 2019 study published in the Journal of Natural History. Goliath frogs appear to use their great size to shift rocks weighing more than 4 pounds (2 kg) to build "nursery ponds" that they clean and guard, Live Science previously reported. 

The world's smallest known frog is a tiny species called Paedophryne amauensis from Papua New Guinea. Described in a 2012 study published in the journal PLOS One, this frog grows to an average length of 0.3 inch (7.7 millimeters), making it the smallest known vertebrate on Earth, Live Science previously reported. 

Frogs are famed for their fantastic jumping skills, but not all frogs hop. Waxy monkey tree frogs (Phyllomedusa sauvagii) walk along branches, gripping them like monkeys do. These South American frogs secrete a natural opioid called dermorphin, which is many times stronger than morphine and has been used to create an illegal performance-enhancing drug for racing horses, according to the World Wildlife Fund. 

Many frogs utilize camouflage, whether it's to stay hidden from predators or blend into their environment so prey don't notice them. For example, Vietnamese mossy frogs (Theloderma corticale) from Vietnam resemble clumps of moss. Poison dart frogs are called the "jewels of the rainforest" because they come in various colors that warn predators they're toxic and shouldn't be eaten. However, even these bright colors can act as camouflage in a vibrant rainforest. 

Glass frogs have translucent green skin that makes their internal organs, and even beating hearts, visible to the human eye. They've evolved for predators to look straight through them. A 2020 study published in the journal Proceedings of the National Academy of Sciences (PNAS) found that these frogs aren't truly transparent, but their camouflage is flexible.

"The frogs are always green but appear to brighten and darken depending on the background," lead author James Barnett, a behavioral ecologist at McMaster University in Ontario, said in a statement at the time. "This change in brightness makes the frogs a closer match to their immediate surroundings, which are predominantly made up of green leaves."

While there are thousands of known frog species, there are likely many more that scientists haven't found yet. For example, researchers described six new species from Mexico in April 2022, and each can fit comfortably on a thumbnail. The researchers noted at the time that the frogs could represent the tip of a giant iceberg of unknown amphibians just in Mexico, Live Science previously reported.  

Related: Adorable 'chocolate frog' discovered in crocodile-infested swamp

Where do frogs live?

Frogs are found on every continent except Antarctica. They need to be around water sources to reproduce, but their habitats are extremely varied otherwise. Poison dart frogs hop through the tropical rainforests of Central and South America, while northern leopard frogs (Lithobates pipiens) inhabit much of North America's marshlands, brushlands and other habitats, including farmland and golf courses, according to the University of Michigan's BioKids website. 

Some species live in highly specialized environments. For example, Vietnamese mossy frogs live in mossy, flooded caves and the banks of rocky mountain streams around 2,300 to 3,300 feet (700 to 1,000 meters) above sea level, according to the Smithsonian's National Zoo & Conservation Biology Institute in Washington, D.C. Meanwhile, desert rain frogs (Breviceps macrops) appear to live exclusively in the white sand dunes of Namibia and South Africa, burrowing into the sand during the day and feeding at night, according to the International Union for Conservation of Nature (IUCN). 

Frogs have lungs, but they can also breathe through their skin by absorbing oxygen from water. They can still drown if their lungs fill with water or there's not enough oxygen in the water they're swimming in, according to the Burke Museum. 

What do frogs eat?

Frogs have a wide diet that includes insects, spiders, worms, slugs, larvae and small fish. These amphibians play a vital role in the world's ecosystems by helping to keep insect populations under control, according to the San Diego Zoo. They catch prey using their quick, sticky tongues. A 2017 study published in the Journal of the Royal Society Interface found that frog tongues can catch insects in 0.07 second — five times faster than the blink of a human eye. 

Related: Watch this frog light up after it swallows a firefly

Some frogs seek out much larger prey than flies and slugs. For example, cane toads (Rhinella marina), which typically grow to 9 inches (23 cm) in length, scarf down small birds, mammals and snakes with ease, as well as other amphibians and even table scraps and pet food, according to the Florida Fish and Wildlife Conservation Commission. Their native range stretches from the Amazon basin in South America up to southern Texas. But humans have introduced cane toads elsewhere, and their insatiable appetites can be a big problem for wildlife. They are an invasive species in areas such as Florida and Australia, where they compete with native amphibians and poison animals that try to feed on them, including pets and, in Australia's case, endangered species such as Tasmanian devils (​​Sarcophilus harrisii), according to the San Diego Zoo.

How do frogs reproduce?

Frogs have many mating strategies, and scientists are still learning about these animals' sex lives. For most species, mature males initiate the breeding process by calling loudly to tell females they are ready to mate, according to the Australian Museum in Sydney. Females filled with eggs approach calling males and choose one to mate with, usually in water. Fertilized eggs, or frog spawn, can incubate for anywhere between 48 hours and 23 days before hatching, depending on the species, according to the San Diego Zoo. Small, legless, fish-like tadpoles emerge from the eggs and begin life feeding on algae.  

Tadpoles' transformation into mature frogs starts with the release of hormones from their thyroid glands, according to the book "Developmental Biology" (Sinauer Associates, 2000). Over time, tadpoles grow legs, lose their tails and emerge from the water capable of living on land. The word "amphibian" comes from the Greek words "amphi" and "bios," which translate to "both life," because they live in water and on land, according to the Oxford Learner's Dictionaries.  

Related: 'Ancient death trap' preserved hundreds of fossilized frogs that drowned during sex

Do frogs hibernate?

Frogs are ectothermic, or "cold-blooded," like other amphibians, reptiles and snakes. This means they can't regulate their own body temperature internally like mammals do, and they rely on the external environment to stay warm, according to Froglife, a conservation charity based in the U.K. To survive winter in colder environments, frogs may go into a state of dormancy, called brumation, underwater or under log piles. Brumation is similar to hibernation, except frogs may occasionally emerge from their dormant state to eat. 

Wood frogs (Lithobates sylvaticus) have an even more extreme winter survival strategy to survive in the northern forests of Alaska and Canada: They allow ice to fill their abdominal cavities and encase their internal organs. In this state, wood frogs' hearts stop beating and they appear to be frozen solid, but they're still alive in a state of suspended animation. The frogs survive because their livers produce glucose that prevents their cells from freezing. They begin to thaw out in spring, and at some point — though scientists aren't sure how — their hearts start beating again and they go on their way, according to the National Park Service. 

Are frogs poisonous?

The bumps on amphibians' skin aren't warts, and people can't contract warts from handling these animals. The myth that people can get warts from frogs likely stems from the wart-like appearance of the bumps, according to the Burke Museum. However, many frogs produce poisonous secretions that can irritate human skin or cause serious harm if ingested. For example, the most toxic poison dart frogs in the genus Phyllobates produce batrachotoxin, which disrupts the human body's nervous system and can cause paralysis, extreme pain and heart failure. As well as potential toxins, frogs can carry bacteria and parasites, according to the Burke Museum. 

The secretions of frogs have played an important role in the development of human medicine; they're used, for example, to make painkillers and antibiotics. Furthermore, around 10% of physiology and medicine Nobel Prize winners used frogs as part of their research, according to Save the Frogs, an amphibian conservation charity based in California.

A few frogs are venomous as well as poisonous. Poison is harmful if ingested, but animals are venomous if they inject their toxins. A 2015 study published in the journal Current Biology found that two Brazilian frog species possessed bony spines on their skulls that they could use like venomous fangs. These frogs, called Bruno's casque-headed frogs (Aparasphenodon brunoi) and Greening's frogs (Corythomantis greeningi), headbutt potential predators to stab them with the spines and transfer toxins, according to the Natural History Museum in London.

Related: Frogs' skulls are more bizarre (and beautiful) than you ever imagined

Are frogs endangered?

Amphibians are the most threatened group of vertebrates on Earth; 40% of the amphibian species assessed by the IUCN are at risk of extinction. This means that many frog species are declining and need help from humans if they are to survive. According to the IUCN SSC Amphibian Specialist Group, some of the main threats facing amphibians are habitat loss and degradation, pollution, disease, invasive species, trade and climate change. 

Frog extinction has disturbing implications for humans. The amphibians are highly susceptible to environmental disturbances, making frog populations a good indicator of the health of an environment, according to Save the Frogs. Therefore, the sheer number of amphibians at risk of extinction can be viewed as a wake-up call for the environmental damage that humans are causing to the planet. 

Additional resources

For more information about how venomous frogs headbutt potential predators, watch this short YouTube video from the Natural History Museum in London. For tips on how to help your local frogs, check out the National Wildlife Federation website. To learn more about different frog species, check out "Frogs and Toads of the World" (Princeton University Press, 2011). 

This article was originally written by Live Science contributor Alina Bradford and has since been updated.

The hatchlings of the invasive cane toad in Australia don't stand a chance against their deadliest predator: cannibal tadpoles who guzzle the hatchlings like they're at an all-you-can-eat buffet. But now, the hatchlings are fighting back.

They're developing faster, reducing the time that hungry tadpoles have to gobble them up, a new study finds. 

"If cannibals are looking for you, the less time you can spend as an egg or hatchling, the better," said study lead researcher Jayna DeVore, who did the research as a postdoctoral research associate at the University of Sydney and is now a biologist for the Tetiaroa Society, a nonprofit conservation organization in French Polynesia. 

Developing quickly, however, has its pitfalls. Compared with typically growing hatchlings, those that grew faster fared worse when they reached the tadpole stage of life, the researchers found. So it isn't "worth it to try to defend yourself in this way unless cannibals are definitely coming for you," DeVore told Live Science.

Related: Image gallery: Invasive species 

The cane toad (Rhinella marina) is a poster child for invasive species. The warty toxic toad, notorious for gulping down anything that fits into its wide mouth, is native to South America. In the 1930s, farmers in Queensland, Australia, thought the toad would be the perfect predator to gobble up beetles that were destroying sugarcane fields. But with no natural predators Down Under, the toad population ballooned from only 102 individuals to more than 200 million, according to WWF Australia. 

Another reason for their population spike is that female toads can lay more than 10,000 eggs at a time in small ponds. "When these eggs first hatch, the young can't swim or eat yet, so they can pretty much only lie there on the bottom of the pond until they develop into tadpoles," DeVore said.

The hungry tadpoles strike during this vulnerable hatchling period. "Once the hatchlings develop into tadpoles, they are too large and mobile for other tadpoles to eat them, so the cannibals have to work quickly if they want to consume them all," DeVore said.

Tadpoles that cannibalize the younger generation are doing themselves a huge favor; they're getting nutrients and eliminating later competition for resources. "When I first saw this behavior in the wild, I was amazed at how voraciously cane toad tadpoles sought out cane toad hatchlings and ate them," DeVore said. To determine whether this behavior was "normal" or whether it was an adaptation to extreme competition among invasive cane toads, DeVore and her colleagues compared Australia's invasive cane toads with the native-range ones, or cane toads from their indigenous regions.

Warty toad arms race

Several experiments revealed that the invasive toads — both the hatchlings and the cannibalistic tadpoles — are evolving at breakneck speed. 

In one experiment done more than 500 times with different individuals, DeVore and her colleagues placed one tadpole in a container with 10 hatchlings. Although the native-range tadpoles did engage in some cannibalism, "we found a hatchling was 2.6 times as likely to be cannibalized if that tadpole was from Australia than if it was from the native range," she said.

Moreover, the invasive tadpoles were much more attracted to the hatchlings than the native tadpoles were. In another experiment, the team placed tadpoles in a pool with two traps; one trap held hatchlings, and the other was empty. "In Australia, the cannibalistic tadpoles were attracted to the hatchlings; the odds that an Australian tadpole would enter the trap containing hatchlings were about 30 times those of it entering the empty trap," DeVore said. 

Related: Survival of the grossest: 8 disgusting animal behaviors 

In contrast, the native-range "tadpoles were not attracted to the hatchlings; they were just as likely to enter the empty trap as the hatchling trap," she said. "This demonstrated that this strong attraction to the vulnerable hatchling stage, which is what helps the cannibalistic tadpoles to detect and locate their victims in Australia, is not present in the native range."

Fighting back

To fight back, invasive hatchlings have evolved an escape strategy. When the researchers compared the time eggs and hatchlings spent developing, they found that the invasive toads developed faster than the native-range ones.

In both groups, "we found that cane toad clutches from Australia developed more quickly; they reached the invulnerable tadpole stage in about four days, whereas native range clutches took about five days," DeVore said.

In addition, the invasive hatchlings had a more "plastic," or flexible response than the natural-range hatchlings when a cannibal tadpole was present; the hatchlings from Australia were "more likely to be able to smell when cannibals are around and actually accelerate their development in response," DeVore noted.

While these strategies helped the hatchlings survive, they paid for it later. The researchers tested 1,190 tadpoles for survival, development, growth and plasticity, and found that those that developed faster as eggs and hatchlings to escape cannibalism fared worse and developed more slowly at the tadpole stage than the native-range tadpoles, the team found. 

Could cannibalism lead to extinction?

Could the cane toads eat themselves into extinction? Probably not, DeVore said.

"Australian cane toads may well be their own worst enemy, but I wouldn't expect them to go extinct anytime soon," she said. That's because the cannibals benefit too much from eating their own kind. After gaining nutrients and limiting competition, the cannibalistic tadpoles "transform into toads more quickly and at a larger size," she said. It's even possible that these "successful" toads will more rapidly invade new places in Australia.

"The good news is that cannibalism can control population growth," DeVore said. "So, although cane toads are unlikely to drive themselves extinct, these cannibalistic behaviors may help to regulate their abundance post-invasion."

The study was published in the Aug. 31 issue of the journal Proceedings of the National Academy of Sciences.

Originally published on Live Science.

For knife-toothed kukri snakes, the tastiest parts of a frog are its organs, preferably sliced out of the body cavity and eaten while the frog is still alive. After observing this grisly habit for the first time in Thailand, scientists have spotted two more kukri snake species that feast on the organs of living frogs and toads.

The new (and gory) observations suggested that this behavior is more widespread in this snake group than expected. Two snakes also eventually swallowed their prey whole, raising new questions about why they would extract the living animals' organs first.

The scientists documented a Taiwanese kukri snake (Oligodon formosanus) and an ocellated kukri snake (Oligodon ocellatus) pursuing amphibian organ meals, tearing open frogs' and toads' abdomens and burying their heads inside, according to the studies. O. formosanus would even perform "death rolls" while clutching its prey, perhaps to shake the organs loose. As the snakes swallowed the organs one by one, the amphibians were still alive. Sometimes, the process would take hours, the researchers reported.

Related: Beastly feasts: Amazing photos of animals and their prey

There are 83 species of kukri snakes in the Oligodon genus in Asia. The snakes typically measure no more than 3 feet (100 centimeters) long, and the group's name comes from the kukri, a curved machete from Nepal, as its shape is reminiscent of the snakes' large, highly modified rear teeth. Kukri snakes use these teeth for slicing into eggs, but they can also be formidable slashing weapons (as some very unfortunate frogs have discovered).

In one study, published Feb. 15 in the journal Herpetozoa, scientists described three snake attacks on rotund banded bullfrogs (Kaloula pulchra), which are so round that they are also known as bubble frogs or chubby frogs. They have brown backs with lighter stripes down their sides and cream-colored stomachs, and they measure up to 3 inches (8 cm) long, according to Thai National Parks. 

Two of the attacks were by Taiwanese kukri snakes, and took place in Hong Kong in October 2020. One snake, filmed on Oct. 2 in a residential neighborhood garden, emerged from a hole in the ground to bite a passing bubble frog, slicing open the frog and stuffing its head inside. Snake and frog tussled for about 40 minutes; the snake performed about 15 body rotations, or "death rolls," during the battle, according to the study. 

"We believe that the purpose of these death rolls was to tear out organs to be subsequently swallowed," Henrik Bringsøe, lead author of both studies and an amateur herpetologist and naturalist, said in a statement.

A second Taiwanese kukri snake was discovered on Oct. 8 in an urban park while "energetically" dining on a frog's organs that were "exposed and visible," the study authors wrote.

The third attack on a bubble frog was by a small-banded kukri snake — the species that was first documented exhibiting this behavior — on Sept. 15, at a factory site outside a small village in northeastern Thailand. During the struggle, the snake performed 11 death rolls, its teeth buried firmly in the frog's belly.

"The snake’s efforts resulted in its teeth penetrating the abdomen to such an extent that blood and possibly some organ tissue appeared," the scientists reported. "Eventually, the frog was swallowed whole while still alive."

Another study, published on the same day in Herpetozoa, presented an observation of an ocellated kukri snake feasting on an Asian common toad (Duttaphrynus melanostictus) inside a lodge in a national park in southern Vietnam. These toads are stout, thick-skinned and variably colored, and they measure about 3 inches (8.5 cm) long, according to Animal Diversity Web, a biodiversity database maintained by the University of Michigan's Museum of Zoology. 

Observers recorded this attack on May 31, 2020. The toad was already dead at the time, "and the snake was moving its head and neck side to side as if trying to work its way inside," the study authors wrote. Minutes later, the snake gulped down the toad whole.

In the 2020 study about small-banded kukri snakes eviscerating Asian common toads, the scientists hypothesized that the snakes selectively ate the organs to avoid the toads' deadly toxins. However, the ocellated kukri snake swallowed the toad after its organ appetizer, hinting that the snakes might have some natural resistance to the toads' poison. 

Chubby frogs also have a built-in deterrent that may encourage predators to go straight for their organs. While the frogs aren't toxic, they defensively secrete a sticky mucous that has an unpleasant taste, according to the University of California, Berkeley's AmphibiaWeb.

"We hope that future observations may uncover additional aspects of the fascinating feeding habits of kukri snakes — though we may indeed call them gruesome!" Bringsøe said in the statement.

Originally published on Live Science.

Pity the toads that encounter Asian kukri snakes in Thailand. These snakes use enlarged, knifelike teeth in their upper jaws to slash and disembowel toad prey, plunging their heads into the abdominal cavities and feasting on the organs one at a time while the toads are still alive, leaving the rest of the corpse untouched.

While you're recovering from the horror of that sentence, "perhaps you'd be pleased to know that kukri snakes are, thankfully, harmless to humans," amateur herpetologist and naturalist Henrik Bringsøe, lead author in a new study describing the gruesome technique, said in a statement.

This grisly dining habit was previously unknown in snakes; while some rip chunks from their prey, most snakes gulp down their meals whole. Scientists had never before seen a snake Bury its head inside an animal's body to slurp up organs — sometimes taking hours to do so, Bringsøe and his colleagues reported. 

Related: Beastly feasts: Amazing photos of animals and their prey

The victims of this horrific organ-slurping were poisonous toads called Duttaphrynus melanostictus, also known as Asian common toads or Asian black-spotted toads; they are stout and thick-skinned, measuring about 2 to 3 inches (57 to 85 millimeters) in length, according to Animal Diversity Web (ADW), a wildlife database maintained by the University of Michigan's Museum of Zoology. During the deadly battle, the toads fought "vigorously" for their lives, with some defensively secreting a toxic white substance, according to the study. The snakes' grisly evisceration strategy could be a way to avoid the toad's poisonous secretions while still enjoying a tasty meal, the researchers wrote.

Kukri snakes in the Oligodon genus are so named because their slashing teeth resemble the kukri, a forward-curving machete from Nepal. While kukri snakes aren't a threat to people, their teeth can cause painful lacerations that bleed heavily, because the snakes secrete an anticoagulant from specialized oral glands, according to the study.

"This secretion, produced by two glands, called Duvernoy's glands and located behind the eyes of the snakes, are likely beneficial while the snakes spend hours extracting toad organs," Bringsøe explained.

Macabre mealtime

The researchers described three observations in Thailand of kukri snakes (Oligodon fasciolatus), which can measure up to 45 inches (115 centimeters) long, consuming Asian common toads. In the first incident, which took place in 2016, the toad was already dead when the witnesses discovered the scene, "but the soil around the two animals was bloody, indicating there had been a fight which eventually killed the toad," the scientists wrote. The snake sawed through the toad's body by swinging its head from side to side; it then slowly inserted its head into the wound "and subsequently it pulled out organs like liver, heart, lung and part of the gastrointestinal tract."

In a second event, an epic battle between a kukri snake and a toad on April 22, 2020 lasted nearly three hours; the snake attacked, withdrew, and attacked again, deterred only temporarily by the toad's poison defense. After finally subduing the toad, the snake extracted and swallowed organs while the toad was still breathing, according to the study. 

On June 5, 2020, a kukri snake took a different approach and didn't disembowel the toad at all, instead devouring it whole. But in a fourth observation this year on June 19, the snake eviscerated its toad prey, slicing into the abdomen to reach its organ meal.

Young toads potentially produce less poison than adults do, which may have enabled the snake in the June 5 observation to safely gulp it down in one piece; another possibility is that kukri snakes are immune to the toad species' toxins, but they disembowel adults anyway because the toads are simply too big for them to swallow, the researchers reported. 

However, there's not yet enough data to answer these questions, Bringsøe said in the statement. 

"We will continue to observe and report on these fascinating snakes in the hope that we will uncover further interesting aspects of their biology," he said.

The findings were published online Sept. 11 in the journal Herpetozoa.

Originally published on Live Science.

Scientists recently took to Twitter to puzzle over an unusual sight captured by a biologist in photos and video: a toad that had no face.

The toad, a fully grown adult, had a healthy-looking body and legs, but it was entirely lacking eyes, a nose, jaws and a tongue. Instead of a face, it had only a stump covered by smooth tissue and a small opening where its mouth used to be, according to herpetologist Jill Fleming, who discovered the toad.

It "kept hopping into things," Fleming tweeted.

Fleming spotted the unfortunate creature — an American toad (Anaxyrus americanus) — in April 2016 in a state forest in Connecticut, where she was conducting research on Eastern red-spotted newts, she told Live Science in an email. [In Photos: The World's Freakiest Looking Animals]

"We sat down on a log to process the samples, and the toad kept running into our feet. When we looked closer, we realized it had no face!" Fleming wrote in the email.

Fleming tweeted a photo of the faceless toad on Feb. 27; she suggested that it had probably recently emerged from brumation — reptile hibernation — looking this way. In the tweet, she invited her fellow herpetologists, or "herp Twitter," to consider what might have caused the animal's highly unusual condition.

Video of the toad showed it tentatively stepping over the forest floor, and there was no sign of a wound where its face presumably once was. However, Fleming explained that its facelessness was probably not the result of a genetic mutation, as the toad was missing a lot of the anatomy required for feeding and couldn't have made it to adulthood without being able to hunt.

Pre-hibernation fat reserves padding the toad's body were likely helping to keep the creature alive, Caruso added. But the hapless toad's chances of surviving in this condition were "really poor," and it likely wouldn't have lasted for very long after running into the researchers, Fleming told Live Science.

"It probably couldn't eat in this condition. Plus, it kept bumping into us, so if we were its natural predators, it would have been eaten very quickly," she said.

Original article on Live Science.

Toads might want to be careful what meal they catch with their sticky, pink tongues. It could be a toxic beetle that makes them throw up … and then scurries away to tell the tale, a new study from Japan finds. 

Unfortunately, toads have to learn this lesson the hard way. After nabbing these brown and black insects, known as bombardier beetles (Pheropsophus jessoensis), a toad will likely feel an explosion in its gut, indicating that the beetle has just let loose a toxic chemical cocktail, the researchers found.

This hot, chemical spray is so powerful that it can prompt the toad to evert its stomach — that is, turn it completely inside out — so the amphibian can vomit out the beetle. At this point, the insect is covered with mucus from the toad's stomach, but still wriggly and, most importantly, alive, the researchers said. [Gallery: Out-of-This-World Images of Insects]

There are 649 species in the bombardier beetle tribe, but the defensive strategies of only a few are known. So, the researchers in the new study decided to take a closer look at P. jessoensis by observing exactly what happened to toads that ate the insects.

But first, the experiment required some fieldwork. The researchers collected 37 adult P. jessoensis beetles, 23 Bufo japonicus toads and 14 Bufo torrenticola toads from a forest's edge in central Japan.

Then, the puking began. The researchers gave each toad one beetle and watched what happened. Soon after the toads gobbled up the beetles, a chemical "explosion was audible inside each toad," the researchers wrote in the study. Not every beetle made it out alive, however.

Just 35 percent of the B. japonicus toads threw up, compared to about 57 percent of the B. torrenticola toads. It took from 12 minutes to nearly 2 hours for some toads to throw up, but most averaged just under 50 minutes to hurl. And once a beetle made it out, it was good to go.

"All 16 beetles that the toads vomited up were still alive and active," and 15 of those beetles lived for at least two weeks after the ordeal, the researchers said in the study.

What's more, the toxic cocktail was clearly the reason for the beetles' survival. When the researchers "treated" the beetles so they couldn't eject their spray, 100 percent of the B. japonicus toads ate the insects and about 85 percent of the B. torrenticola easily gulped down the critters.

Survivor beetles

An analysis revealed that size truly does matter, at least when trying to make toads upchuck. Larger beetles were more likely to survive than small beetles, and small toads were more likely to vomit than large toads, the researchers found. This is likely because "large beetles can eject more defensive chemicals than small beetles, [and] large beetles are more likely to survive the toad digestive system than small beetles [are]," the researchers wrote in the study.

As for the amphibians, "small toads have a lower toxic tolerance than large toads," the researchers wrote.

The investigators also found that the beetles fared better in the B. japonicus stomachs, with an 82 percent survival rate, compared to a 72 percent rate for B. torrenticola toads. It appeared that although B. torrenticola had a higher rate of vomiting, it also had more-potent digestive abilities than the other toad. [40 Freaky Frog Photos]

In Japan, the bombardier beetle lives around more B. japonicus toads than B. torrenticola toads, the researchers said. Perhaps, B. torrenticola has a lower tolerance for the beetles' surprising spray because that toad rarely encounters it, the researchers said.

The scientists noted that the experiments did not seriously harm or kill the toads, which were released back into the wild after the trials. The researchers couldn't, however, say the same for the beetles. 

The study was published online Feb. 7 in the journal Biology Letters.

Original article on Live Science.

When it's just too darn hot, amphibian young adapt by changing their diet, weathering heat with vegetarian fare.

In a new study, tadpoles representing three frog species were exposed to mock "heat waves" in the laboratory to test how amphibians in the wild might respond to warmer-than-average conditions due to climate change.

When temperatures rose, so did the tadpoles' preference for vegetarian menus, the researchers found; the tadpoles consumed more plant-based meals when the controlled environments were hotter. [40 Freaky Frog Photos]

Scientists are particularly interested in how the dietary needs of amphibians and other ectotherms, or "cold-blooded animals" — those that use external sources to regulate body temperature — may be affected by a warming world, the researchers wrote in the study. Changes in temperature can affect how efficiently ectotherms process their food, and shifting to a more plant-based diet could help them compensate for those metabolic changes, the researchers said.

As climate change is spawning more frequent and more intense heat waves, the researchers wanted to see if amphibian young — tadpoles — would change their diets when exposed to artificial "heat waves."

In the study, the first to explore temperature-related diet changes in vertebrates, the scientists looked at three frog species that were native to the Iberian Peninsula in southwest Europe. The researchers collected eggs belonging to the Iberian painted frog (Discoglossus galganoi), the European tree frog (Hyla arborea) and the Mediterranean tree frog (Hyla meridionalis). The eggs were installed and hatched in aquariums in a laboratory.

In the experiment, the researchers gradually heated up the tadpoles' watery homes for periods lasting from one week to two months, to simulate how pond habitats might warm during a naturally occurring heat wave. They provided the growing tadpoles with meals of insect larvae and plant stalks, and then observed what the tadpoles ate and how their health and growth were affected.

"Normal" water temperature for the tadpoles was established at 70 degrees Fahrenheit (21 degrees Celsius), but then things heated up — temperatures sometimes rose as high as 77 degrees Fahrenheit (25 degrees Celsius) for days at a time. Although the three species had somewhat different diets, all consumed a higher percentage of plants, perhaps because they could process them more quickly, study co-author Germán Orizaola, a researcher in the Department of Ecology and Genetics at Uppsala University in Sweden, told Live Science in an email.

"Vegetarian diets are easily assimilated by animals under warm conditions — much easier than protein-rich animal diets," Orizaola said.

This is the first evidence that higher temperatures could drive ectotherms to increase their plant intake, and the first study to show this degree of flexibility in diets as animals adapt to climate change, the authors wrote.

But it also hints at how ecosystems — and the dietary needs of their inhabitants — could change in a warming world. Orizaola explained that if more amphibians require algae and plants to survive, the availability of those resources goes down, which, in turn, can affect other animals and even reduce water quality.

"This study provides us with information about how to manage freshwater environments exposed to the challenges of climate change," he added.

The findings were published online today (Nov. 3) in the journal Ecology.

Original article on Live Science.

NEW YORK — Neon green, vivid orange, striped and spotted — the frogs are back! An exhibit featuring live frogs from around the world is returning to the American Museum of Natural History here in New York.

The exhibition, entitled "Frogs: A Chorus of Colors," features more than 150 live frogs from approximately 25 species, from the brilliantly colored poison dart frog to the giant African bullfrog. The exhibit opens Saturday (May 18) and runs through Jan. 5, 2014.

"Frogs are so weird that although we might think we know frogs really well, there's just so much about their biology and what they do which is a chance in the exhibition to really surprise people," exhibit curator Christopher J. Raxworthy, a curator in the museum's department of herpetology and faculty member in its Richard Gilder graduate school, told LiveScience at a press preview of the exhibit.

The display introduces visitors to the biology and evolution of these wacky and wonderful amphibians, as well as their importance to ecosystems and the dangers they face. The colorful creatures, which were bred in captivity, peer through glass cases containing recreations of their natural habitats. [Image Gallery: Cute and Colorful Frogs]

Highlights include the pale-blue Mexican dumpy frog from the semiarid subtropical lowland forests in Mexico and the appropriately named tomato frog from the lowlands of Madagascar.

The frogs possess a certain mystique for visitors. People are drawn to the amphibians' bright colors and strange physiques. "I think that, aesthetically, it really gives people a high," Raxworthy said. In addition, there are the quirky things frogs do.

For example, many frogs swallow using their eyeballs. "Once they have prey in their mouth, to help force it down their throat, they actually pull their eyeballs down," Raxworthy said. And here’s another wacky tidbit: African clawed frogs were once used for pregnancy tests.

The exhibit's centerpiece is a large poison-dart-frog vivarium containing more than 80 frogs, including bumblebee poison frogs, Bastimentos strawberry poison frogs and green-leg poison frogs. In the wild, poison dart frogs concentrate the toxins found in ants and other insects they eat into a powerful poison that the Emberá, the indigenous people of northwestern Columbia, rub onto darts for weapons.

Active research in the museum's department of herpetology is also featured in the exhibit. Biologists are still discovering new frog species. More than 6,000 species have been described so far, and that number is increasing rapidly, Raxworthy said.

Nonetheless, frog populations are dwindling around the world, and the exhibit features a short video about some of the threats frogs face. Nearly one-third of amphibians — 88 percent of which are frogs — are threatened, and at least 34 species of frogs (and possibly many more) are extinct. Habitat loss is a major cause, but a mysterious disease caused by the chytrid fungus is also to blame.

"There's lots we don't fully understand, but it’s very sad to see a big chunk of amphibian diversity now also suffering because of this disease," Raxworthy said.

The purpose of the exhibit is to educate people about these fascinating creatures, Raxworthy said. For visitors, he said, "This is a great chance to find out interesting facts about frogs you probably have no idea about. The more you dig, the more weird and wonderful it gets."

Follow Tanya Lewis on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on LiveScience.com. 

Bumblebee Dart Poison Frog

A new exhibit featuring live frogs from all over the world is opening at the American Museum of Natural History in New York Saturday (May 17) and runs through January 5, 2014.The exhibition, entitled "Frogs: A Chorus of Colors," contains more than 150 live frogs from about 25 species. Above: Bumblebee dart poison frogs are also known as yellow-banded poison frogs. Their bright colors serve as warning labels forpredators, distinguishing them as a poisonous meal.

Giant Monkey Frog

Giant monkey frogs are found in the Peruvian and Brazilian Amazon. Males call from high above the ground and descend to branches just above ponds to mate. The call is a loud “cluck” followed by several short, lower-pitched notes.

Brazilian Milk Frog

During the mating season, the loud call of the male milk frog leads a female to his water-filled tree hollow. The female lays her eggs in the pool and leaves the male to fertilize them and care for the young. After the tadpoles hatch, the male lures another female to lay more eggs, but instead of fertilizing them, he feeds them to his hungry tadpoles. By “faking” a love interest, he tricks the second female into delivering food for babies that are not hers.

Blue Dart Poison Frog

Blue dart poison frogs grow to approximately one inch in length. They are active during the day and can be found hiding among boulders and debris near streams; however, they lack toe webbing and are poor swimmers, so they are rarely found in the water.

Ornate Horned Frog

Ornate horned frogs live in the rainforests and pampas prairies of Uruguay, Brazil, and northern Argentina. Voracious eaters, horned frogs bury themselves in leaves or loose soil and pounce on small animals that blunder by.

Tomato Frog

Tomato frogs are native to the lowlands of Madagascar. Brightly colored frogs are popular with pet owners and collectors. While many frogs are bred in captivity, over-collection of wild frogs is still a major problem. Frogs that live on islands or in small populations are most at risk. Tomato frogs have been given priority protection by international law.

Mexican Dumpy Frog

Mexican dumpy frogs are from semi-arid subtropical lowland forests in Mexico. They spend almost the entire lives off the ground, living in tree canopies, on branches and leaves. They are excellent climbers.

American Bullfrog

More than a century ago, American bullfrogs were introduced into the western United States in the hope that they could be farmed for food. Although the farming efforts failed, the bullfrog adapted to man-made ponds and waterways and is now a threat to native species of fish, snakes, birds, and other frogs—some of them endangered.

Fire-bellied Toad

Fire-bellied toads use skin color for protection—the green and black skin on their backs provides camouflage. When disturbed, the toads throw their legs in the air, revealing a bright orange “fire belly.” If flashing these bright colors doesn’t scare the predator, the toad has toxic skin secretions that make it an unpalatable meal.

Borneo Eared Frog

Borneo eared frogs are indigenous to Borneo,Sumatra, and other Indonesian islands. Females lay eggs in foam nests attached to branches overhanging the water. They create the nests by beating a frothy secretion into foam with their hind legs.

A type of ground beetle has a strange snacking habit. New research finds the Epomis beetle opportunistically kills and eats amphibians many times its size — animals that usually prey upon the insect.

The beetle's normal diet consists of other invertebrates, such as insects, worms and dead vertebrates, but every time they were put in an enclosure with an amphibian, they attacked and consumed it, the researchers said.

"Amphibians are typical insect predators, and their diet may include adult beetles, ground beetles in particular," study researcher Gil Wizen, at Tel Aviv University in Israel, said in a statement. "The recently filmed successful attacks of the beetles on toads and frogs brought new insights on the amphibian-insect interactions, and documented the uncommon phenomenon of invertebrates preying on vertebrate animals."

In a sick twist of fate, the beetles often like to get to know their meals before dinnertime; in the wild, the researchers frequently found the two sharing shelter during the day, before things turn deadly at night. The beetles aren't picky eaters, either. They prey on amphibians of all types, from frogs and toads to newts and salamanders.

The beetle kills the amphibian by biting it on the back, to which the frog or toad reacts violently, trying to swing the beetle off. The beetle makes an incision in the amphibian's back, which paralyzes it within a few minutes, then slowly devours it from the legs up, usually taking several hours to complete the meal. [Video – Watch the beetle in action]

The study was published in the journal ZooKeys.

You can follow LiveScience staff writer Jennifer Welsh on Twitter @microbelover. Follow LiveScience for the latest in science news and discoveries on Twitter @livescienceand on Facebook.

A trio of amphibians – including a toad with ruby eyes, another with a long beak and a penchant for taking cover on dead leaves, and a frog sporting "racing stripes" on its legs – are thought to be completely new to science, researchers who discovered the gang in western Colombia announced Monday (Nov. 15).

"I have never seen a toad with such vibrant red eyes," said Robin Moore of Conservation International, referring to the new toad whose genus is still undetermined. "This trait is highly unusual for amphibians, and its discovery offers us a terrific opportunity to learn more about how and why it adapted this way."

Moore led the September expedition along with Don Church of Global Wildlife Conservation and Colombian scientist Alonso Quevedo of Fundación ProAves. The team was searching for the long lost Mesopotamia beaked toad, which hasn't been seen since the start of World War I, and is considered critically endangered by the IUCN Red List of Threatened Species.

"After spending several days searching for the Mesopotamia beaked toad with no success, the team's spirits were pretty low," Moore said. "But finding these new species, including a new beaked toad, was like a shot of adrenaline. We definitely left on a high."

Meet the trio:

The new species of beaked toad, which belongs to the genus Rhinella, was found in the rainforests of Chocó, Colombia. The color and shape of the toad's head resemble dead leaves, where the about 0.8-inch (2 centimeters) long animal hides out. The toad likely skips the tadpole stage, laying eggs on the forest floor that hatch directly into toadlets.

This Rhinella species, which shows a resemblance to villain Monty Burns on the TV series "The Simpsons," got a nod from series' writer/producer George Meyer, who after seeing the toad's photo said, "The toad's imperious profile and squinty eyes indeed look like Monty Burns."  Meyer is an active member of Conservation International's Chairman's Council.

The ruby-eyed toad is about 1.2 to 1.6 inches (3 to 4 cm) in length and was found on the forest floor. Its discoverers know nothing about this species other than where it lives, which is at an elevation of around 6,560 feet (2,000 meters) in the Chocó montane rainforest.

The rocket frog, belonging to the genus Silverstoneia, is a type of poison dart frog. This small species, growing no larger than 1.2 inches (3 cm) in length, is less poisonous than its brightly colored relatives. The frogs live in and around streams, where they carry newly hatched tadpoles on their backs to deposit them in water to complete their development.

The discoveries came out of the first phase of the Search for the Lost Frogs campaign, which will continue through the end of 2010. 

The scientists say they will continue their search for the Mesopotamia beaked toad. Thanks to support from the U.S. Fish and Wildlife Service, the four organizations involved in the Colombian search have hired a team of young researchers to explore the mountains of Colombia in search of this and other lost species.

The research team included members from Conservation International, the IUCN Amphibian Specialist Group, Global Wildlife Conservation and Fundación ProAves.

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When grasped by a male they do not want to have sex with, female cane toads will inflate their bodies so rival males can dislodge the unwanted suitor.

Researchers recently discovered that this puffing up makes it easier for larger, more desirable male toads to knock puny, but persistent paramours off of a female's back. This novel method of mate selection – never seen before in any animal – gives females some say over who ends up as father of their tadpoles.

"Our study shows that females can exert mate choice by inflating their bodies," said lead author Bas Bruning, an ecologist at Vrije University in Amsterdam, The Netherlands.

It has long been known that toads and frogs can defensively swell themselves with air to increase their body size, a survival trick that intimidates predators and prevents snakes from being able to swallow them. Now it seems that female toads have co-opted this tactic in the evolutionary battle of the sexes.

Froggy style

Sex in many toads, frogs and other amphibians involves a male mounting a female's back and gripping her by the armpits. This amorous embrace, called amplexus, places the animals' cloacas – an all-purpose orifice at the rear that excretes feces, urine, eggs and sperm – close together.

Fertilization is best assured when the toady couple is similar in size and their cloacas line up, said Bruning. In most toads, females are the larger sex, so they benefit from shacking up with the bigger males in the swamp.

Mating season competition, however, is intense. Male cane toads gather around suitable waterholes, croak out to attract mates and jump on any female when she approaches. The males then battle each other for the best or – ideally for one of them – the sole amplexus position.

The expecting female, who must lay her eggs at a certain point in their maturation, enters the watery pool with a male (or males) on her back. The males release sperm as the female lays tens of thousands of eggs in long strings. Sometimes the female actually ends up drowning when too many lusty fellows gang-tackle her.

Big love

To see if females could influence the outcome of these reproductive encounters, researchers rounded up dozens of cane toads, an invasive species that is wrecking ecological havoc in much of Australia. A catheter was placed in some of the female toads' throats that prevented them from trapping air and swelling up.

The female toads were then placed in tanks along with three eager males to simulate a competitive boggy dating scene.

The smallest males in the experiment were allowed first dibs at the females. The little, though as it turns out, lucky guys who latched onto females that could not inflate themselves were never knocked off by their bigger male rivals, even over the span of several hours.

With the ballooning females, however, larger males dispossessed the tiny toads in four out of seven trials. "We found the number of male takeovers is much higher when females can inflate than when they cannot," Bruning said.

Though this inflation-influenced courtship has not been witnessed outside of the lab, "we do think it occurs in the wild," Bruning said, adding that scientists likely have not noticed it because a pumped-up female "is usually interpreted as 'agitation' and not associated with sexual behaviors."

Edmund Brodie, a professor of biology at Utah State University who was not involved with the study, finds the evidence compelling.

"This is a study that is novel and presents a new hypothesis on frog mate choice," Brodie told LiveScience. "The [paper's] conclusions are justified."

Researchers believe these extra-voluptuous females are harder to hold onto for at least two reasons: the male frog's embrace is stretched out more, and the female's body is less supple when plumped up to perhaps half-again her normal size.

By way of analogy, Bruning said "it is easier to grasp a tennis ball than a football with one hand … [and] the football is much easier to grasp if it is only half-filled with air."

Safe or sex?

Forms of mate selection that double as defensive strategies, or vice versa – such as bodily inflation in toads – might be a common but overlooked phenomenon amongst other animals.

"Many of the traits that enable a female to repel a predator also allow her to repel unwanted suitors, and hence facilitate mate choice," the researchers wrote in their study, which was published earlier this year in the journal Biology Letters.

For now, it is not known whether avoiding being dinner or being "taken advantage of" came first for the female cane toad. But the fact that body inflation is so widespread in frogs and toads offers a clue, Brodie said.

These creatures have existed much longer than snakes, an example of a predator deterred by air-engorged toads, because snakes must swallow their prey whole. Therefore, "it follows that inflation may have first evolved as mate choice and been co-opted for predator defense," Brodie said.

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Spotted salamanders, poison dart frogs and other color-splashed amphibians will leap aboard a Noah's Ark of sorts this week. The Wildlife Conservation Society has pledged its continuing participation in the Amphibian Ark, a global initiative to save hundreds of critically endangered amphibians from extinction through captive breeding in zoos. On Leap Day, as part of the Amphibian Ark mission, the WCS's Bronx Zoo, the New York Aquarium and other city zoos will raise awareness of the plight of amphibians as they welcome the 2008 Year of the Frog. At least 120 species of frogs, toads, salamanders and other amphibians have perished since 1980, and up to half of the remaining 6,000 species may soon succumb to extinction, according to WCS. Habitat loss, climate change, pollution and diseases have all contributed to the dwindling amphibians. Many species are already benefiting from the safe-nest of WCS zoos. For instance, zoos have bred hundreds of the Kihansi spray toad, a species that is considered extinct in the wild. The tiny toad, whose body is under an inch long, was once found only in an isolated river gorge in Tanzania where fine mist from cascading falls kept away predator safari ants and kept the habitat at a nearly constant temperature. Other slimy stars, such as the endangered Puerto Rican crested toads and Wyoming toads, have been released back into the wild after successful zoo breeding.

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The Asian snake Rhabdophis tigrinus is one tough customer. Not only can it swallow toxic toads and live to tell. It also uses the toad’s poison for its own defense, new research shows.

And rather than deploying the toxin, the snake uses it as the biological equivalent of waving a busted gun.

Where other snakes simply tolerate toxins secreted by their prey, “this is the only snake that’s truly known to use dietary toxins in its own defense,” said Deborah Hutchinson of Dominion University, lead author of the study.

The finding came when Hutchinson's colleague Akira Mori  noticed that R. tigrinus showed some odd differences in behavior: Snakes that lived on Japanese islands with a plentiful toad population [image] would arch their neck and display their toxic neck glands [image] when a predator loomed nearby, but those on toad-free islands usually fled.

That led Mori to suspect that the snakes took the toxin from the toads they ate for supper instead of manufacturing the toxin themselves.

Toads secrete the toxin from their skin as a thick, white, viscous fluid that Hutchinson described as bitter and painful to predators that come into contact with it. (Because it is a cardiotoxin, in large quantity it can even stop a predator’s heart.)

Survival Advantage

To test their hypothesis, the researchers collected both the "fight" snakes and the "flight" snakes from the islands in Japan. Analysis of the snakes' neck gland fluids revealed that snakes from toad-free islands lacked the toxic compounds. The team also found that the glands in all the snakes lacked the cell machinery needed for a toxin factory.

As a means of defense, the snake’s toxic glands are mostly all show—it doesn’t actually release the toxin. It only displays the glands.

Toxin-borrowing is common in invertebrates (Monarch butterflies takes up milkweed toxins, for example), but less so among vertebrates, Hutchinson said, though some frogs are known to take up toxins from ants and other insects they eat.

Toxic yolks

The researchers also experimented with snake hatchlings; when mothers lacked the toxins in their glands, so did their hatchlings.

“The hatchlings lacked these compounds—they only accumulated these toxins when they were fed toads,” Hutchinson told LiveScience.

Mother snakes that do eat the Japanese toads can pass the toxin along to their hatchlings through the egg yolk. In this way, mothers pass on a survival advantage to their young.

“That’s a way to arm their offspring right away,” Hutchinson said.

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Beavers' stream-clogging ways may be pesky to humans, but their dams might be just what some frogs and toads need to survive in their dwindling wetland habitats, a new study concludes.

Cam Stevens of the University of Alberta and his colleagues conducted a survey of the calls of male frogs and toads around streams in parts of the boreal or conifer forests in west-central Alberta, Canada, and found that they only heard their choruses near streams where beaver dams were present.

The scientists? expected to find at least some amphibians near other streams, but "the effect was overwhelming," Stevens told LiveScience.

The researchers also caught three species of frogs and toads and found anywhere from five to 29 times as many young, newly-developed amphibians near streams with beaver dams as near free-flowing streams.

The beavers act as a "surrogate species" that serves as a protective "umbrella" to several species that live in the same habitats, Stevens wrote in the study published in the current issue of the journal Biological Conservation.

Such an umbrella is important because amphibian populations all over the world are declining. The culprits include habitat loss, disease, climate change, and combinations of all these factors.

In Canada's boreal or conifer forests, "there's some evidence to suggest it's habitat loss," Stevens said. Both habitat loss and climate change reduce the number of smaller ponds that amphibians use as breeding grounds.

"These types of ponds are disappearing," Stevens said.

Warm bathtubs

So why is it that frogs are so attracted to beaver dams? By damming up the streams, the beavers are "creating an environment for the tadpoles to grow and develop in," Stevens explained.

The beaver dams create warm bathtubs of oxygen-rich standing water ideal for tadpoles.

"Otherwise these tadpoles and larvae would be washed downstream," Stevens said.

Because the water is warm and still, algae, a favorite food source for tadpoles, can grow more abundantly. The dams also keep predatory fish from swimming upstream and eating the tadpoles.

All these conditions are necessary to the survival of the developing tadpoles, Stevens said.

Boon or nuisance?

While frogs find beavers to be helpful neighbors, beaver dams can be a nuisance to humans because beavers like to build them in culverts and that can cause water to back up and flood roads. In such cases, beavers are often killed or moved to other areas.

Beavers also fell trees that the forest industry would prefer remained standing.

"So beavers are a pest in a lot of situations," Stevens said.

The challenge, he said, is to find places where conflict with humans can be minimized while also allowing beavers to build their dams and provide shelter for developing amphibians. Many forestry companies will likely be helpful with such a plan, he added, because they are interested in contributing to amphibian conservation.

Original article on Live Science.

Global warming is now believed to have set off a chain reaction wiping out entire frog populations and could possibly drive many species to extinction, a new study suggests.

Using records of sea-surface and air temperatures, researchers determined that harlequin frogs are disappearing nearly in step with the warming climate. At least 110 species of brightly colored harlequin frogs once lived near streams in the Central and South America tropics. Nearly two-thirds vanished in the 1980's and 1990's.

According to researchers, the Earth's rising temperatures increase cloud cover on tropical mountains, leading to cooler days and warmer nights. This creates the perfect growing conditions for chytrid fungus--a skin fungus that causes deadly infections in amphibians.

"Disease is the bullet that's killed the frogs," said study leader J. Alan Pounds of the Tropical Science Center's Monteverde Cloud Forest Preserve in Costa Rica. "But climate change is pulling the trigger. Global warming is wreaking havoc on amphibians, and soon will cause staggering losses of biodiversity."

The fungus kills frogs mostly in cool highlands or during winter, which had scientists thinking that low temperatures made it more fatal. However, this evidence shows it grows optimally between 63 and 77 degrees Fahrenheit, suggesting that it flourishes in warm years as well.

In 2004 the Global Amphibian Assessment reported that nearly one-third of the world's 6,000 species of frogs, toads, and salamanders face extinction.

But it's not just bad news for frogs, said Sam Scheiner of the National Science Foundation's ecology of infectious diseases program. As global warming and the emergence of infectious diseases continue, the two will pose an immediate threat to biodiversity and a growing challenge for humans.

"The good news, if there is any, is the new findings will open up avenues of research that could provide scientists with the means to save the amphibians that still survive," study participant Bruce Young of NatureServe said. "If this cloud has any silver lining, that's it."

This research is detailed in the Jan. 12 issue of the journal Nature.

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