Hibernation physiology, freezing adaptation and extreme freeze tolerance in a northern population of the wood frog

Rana sylvatica is a species of wood frog whose special abilities boggle the mind. A study recently published in The Journal of Experimental Biology explains how they manage to be frozen, but not to death.

National Geographic reports, "The tiny amphibians can survive for weeks with an incredible two-thirds of their body water completely frozen—to the point where they are essentially solid frogsicles.

Even more incredible is the fact that the wood frogs stop breathing and their hearts stop beating entirely for days to weeks at a time. In fact, during its period of frozen winter hibernation, the frogs’ physical processes—from metabolic activity to waste production—grind to a near halt. What’s more, the frogs are likely to endure multiple freeze/thaw episodes over the course of a winter."

The frogs have cryoprotectants, or solutes in their blood that dramatically lower their freezing temperature. It protects the body's cells and limits the amount of ice that can form in the body.

By having a higher concentration of these cryoprotectants in its blood, this species of wood frog can survive being frozen even multiple times in a single winter. (Source)

It's been gone since 1983, but the Lazarus Project has brought it back to life.

In 1983, the world lost one of its weirdest frogs. The gastric-brooding frog, native to tiny portions of Queensland, Australia, gave birth through its mouth, the only frog to do so (in fact, very few other animals in the entire animal kingdom do this--it's mostly this frog and a few fish). It succumbed to extinction due to mostly non-human-related causes--parasites, loss of habitat, invasive weeds, a particular kind of fungus. There were two subspecies, the northern and souther gastric-brooding frog, and they both became extinct in the mid-80s sometime.

Except--what if they didn't?

Taking place at the University of Newcastle, the quest to revive the gastric-brooding frog became known as the Lazarus Project. Using somatic-cell nuclear transfer (SCNT), a method for cloning, the project has achieved the major step forward of creating an early embryo of the extinct frog. Essentially, they found a related frog--the great barred frog, which also lives in Queensland and has cool eye markings, like it's wearing sunglasses--deactivated its eggs, and replaced them with eggs taken from the extinct frog.

Even though the gastric-brooding frog has been extinct for decades, it's possible to do this because individual specimens were kept preserved in, believe it or not, everyday deep freezers. When going through somatic-cell nuclear transfer, the eggs began to divide and form into the early embryo stage.


The embryos didn't survive much longer than that, but it was confirmed that these embryos contain genetic information from the gastric-brooding frog--that yes, in fact, they have brought it back to life. The researchers are confident that this is a "technical, not biological" problem at this stage to breed gastric-brooding frogs to adulthood. This is a big step forward for the worldwide attempts to revive extinct animals--the Lazarus Project researchers will soon meet with those working to revive the woolly mammoth, dodo, and other extinct beasties to share what they've learned.


Oh, and in case you were wondering: the gastric-brooding frog lays eggs, which are coated in a substance called prostaglandin. This substance causes the frog to stop producing gastric acid in its stomach, thus making the frog's stomach a very nice place for eggs to be. So the frog swallows the eggs, incubates them in her gut, and when they hatch, the baby frogs crawl out her mouth. How delightfully weird!
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This tiny frog’s “mighty war cry” is intended to ward off predators and attract mates, reports GrindTV, but it’s probably just going to make you say “awww.”

Although it’s been widely identified in the news as a Namaqua rain frog, frog expert (unfortunate professional title: herpetologist) Alan Channing has identified it as a desert rain frog.

I’m pretty sure Mr. Channing knows what he’s talking about, as he’s actually one of the assessors list on the International Union for the Conservation of Nature and Natural Resources (IUCN), which lists the desert rain frog, or Breviceps macrops, as “vulnerable” on its Red List of Threatened Species.

The Pokemon-like sound is also emitted when the frog is in distress, said Mr. Channing, who is a professor and has authored three books on African frogs.

“What this means is that somebody was prodding it and annoying it while the close-up video was taken,” he said.


Dang it, now I’m saying “awww” because I’m sad for the squeaky little guy.

Wildlife photographer Dean Boshoff, who filmed the squeaky frog, said it was already making that sound, and that’s how he noticed it.


“I recorded a short clip of the defensive cry of the Desert rain frog – Breviceps macrops,” Mr. Boshoff wrote in the video’s caption on YouTube. “While walking along the sand dunes in Port Nolloth, a coastal town in the Northern Cape province, it alerted me to its presence with its fearsome war cry. I knelt down and proceeded to photograph and film this unusual creature’s behaviour.”
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The species – known as Helen’s Tree Frog (Rhacophorus helenae) - is bright green with a white belly and has webbed hands and feet like parachutes to glide from tree to tree.

Dr Rowley was stunned to discover the large, 10cm long species surprisingly close to Ho Chi Minh City, an urban centre with over 9 million people.

Dr Rowley said it was incredibly rare and very exciting to find a new species of frog less than 100km from one of the largest cities in South East Asia.

“To discover a previously unknown species of frog, I typically have to climb rugged mountains, scale waterfalls and push my way through dense and prickly rainforest vegetation,” she said.

“I certainly didn’t expect to find a new species of frog sitting on a fallen tree in lowland forest criss-crossed by a network of paths made by people and water buffalo, and completely surrounded by a sea of rice-paddies.”

Dr Rowley said the large frog has likely evaded biologists until now by spending most of its time out of sight, in the canopy of large trees.


Dr Rowley said she chose to name the frog species in honour of her mother, Helen Rowley, who has steadfastly supported her only child trekking through the forests of Southeast Asia in search of frogs.

“My mother was recently diagnosed with ovarian cancer and I thought it was about time that I showed her how much I appreciate everything she’s done for me and everything that she’s put up with over the years,” she said.

To date, Helen’s Tree Frog is only known from two patches of lowland forest in the middle of agricultural land not far from Ho Chi Minh City.


Dr Rowley said lowland forests are among the most threatened habitats in the world.

“Another, more well-known species reliant on lowland forests, the Javan Rhino, was confirmed extinct in Vietnam in October 2011,” she said.

“The new species is at great risk due to ongoing habitat loss and degradation - the greatest threat to amphibians throughout Southeast Asia – but hopefully it has been discovered just in time to help protect it.”
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A rare blue frog was sighted Tuesday by forest preserve volunteers at the Hidden Lake Forest Preserve near Downers Grove.

The bullfrog, spotted by volunteer Jerry Zamirowski of Glen Ellyn, had a rare mutation causing the frog to appear bright blue, according to the DuPage County Forest Preserve District.

It is the first sighting of a bullfrog with that mutation on record in the county.

“When [Zamirowski] sent in the photo we said ‘This is really fascinating,” said DuPage County Forest Preserve District public affairs specialist Bonnie Olszewski. “There are all kinds of reasons why animals might have mutations like genetics or conditions that might cause color mutation, but this bright blue I don’t think we’ve ever seen anything exactly like that before.”

The frog’s vibrant coloration is likely due to an inability to camouflage properly with the green, marshy area, according to Dan Thompson, ecologist at the DuPage County Forest Preserve.

“We’ve learned from school that you mix blue and yellow and you get green, but this individual is without those yellow pigment cells and so it is physically unable to make that green coloration,” he said. “This is one of those just very rare situations.”

The bullfrog appears to be an adult, a surprise to Thompson who declared the frog’s age “pretty incredible since it can’t camouflage itself quite properly.”

Thompson said the mutated frog is a “genetic anomaly,” but it may naturally occur more often than recorded and the animals go unnoticed.(Source)

Four decades after Kermit the Frog first sang "It's not easy being green," amphibians around the planet know all too well how he felt. It's not just difficult being green anymore — these are hard times to be a frog of any color.

Frogs and toads today face a gauntlet of environmental threats, part of what the International Union for Conservation of Nature calls an "amphibian extinction crisis." Nearly one-third of Earth's 6,485 amphibian species are on the brink of extinction, according to Save the Frogs, a California-based conservation group.

One of the biggest factors in this has been the deadly chytrid fungus, which is blamed for major declines or extinctions of more than 200 amphibian species worldwide. But the plight of frogs (and toads, which are technically frogs) is also compounded by many other dangers. Deforestation, wetland loss and climate change are wiping out their habitats; pollution and pesticides are permeating their skin; invasive species are stealing their food; and overharvesting for food and pets is draining their gene pools.

The fourth annual Save the Frogs Day is this Saturday, April 27, organized by Save the Frogs and observed by frog fans from Oregon to Ghana to Bangladesh. In honor of the holiday, here are a dozen photos of frogs and toads from around the world, highlighting the beauty and diversity of Kermit's embattled brethren:

LOOK BEFORE YOU LEAP: An American bullfrog, the largest frog species native to North America, surveys its surroundings in Mountainville, N.Y. (Photo: Nick Harris/Flickr)













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