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Showing posts with label chytrid infecting frogs. Show all posts
Showing posts with label chytrid infecting frogs. Show all posts
Odorrana tormota is one of only two frog species known to have a concave ear. Researchers believe that its unusual ear structure and high-pitched calls are an evolutionary adaptation to a noisy environment. Photo courtesy of Albert S. Feng, University of Illinois.
Last frog blog for awhile. This was just so interesting that I HAD to post it even though there have been a few frog blogs lately. Scientists have discovered a frog that has developed the art of selective hearing just like some humans have.
A rare Chinese frog has been found to have the unusual ability to shift its hearing from one frequency to another the better to selectively choose what it hears.
The frog, Odorrana tormota, is the only known animal in the world to be able to manipulate its hearing system to select particular frequencies with the exception of the human animal. According to scientists; however, we run a very poor second in a race of two. Our hearing system is very slow when compared with that of the frog; and, our ability to tune in or out with precision is also inferior to that of the frog. We definitely ended up being #2 in this race. Or from a different point of view - dead last.
The rare amphibian likely evolved its hearing talent out of necessity, since its environment is so noisy.
"Their calling sites are on the steep banks of a fast-flowing body of water -- the Tao Hua Creek (at Huangshan Hot Springs in central China)," Albert Feng told Discovery News.
Feng, a professor of molecular and integrative physiology at the University of Illinois at Urbana-Champaign, added that the site is particularly noisy after spring showers while pointing out that humans have a similar inability to hear well over heavy rains.
"We pretty much have to shout at one another," he said.
The frog doesn't shout, but it instead sings like a bird either in audible chirp-like frequencies or by emitting very high-pitched ultrasonic sounds. This is the first time a frog has been known to sing in rising and falling harmonies - all other known frog calls go up or down.
Feng and his team were curious as to how this amphibian could hear these different vocalizations. They decided to analyze the frogs’ hearing system which was made much easier than expected since it was discovered that the frogs’ ears are completely transparent. Talk about a natural window!
Using a laser to measure the eardrum’s vibration, the team noticed that the eardrum responded to both audible and ultrasonic sounds. Interestingly, the eardrum’s sensitivity to ultrasonic noise sometimes mysteriously disappeared.
Discovery News tells us:
“Further investigation determined the frog actively opens and closes two narrow channels known as the Eustachian tubes, which connect the pharynx (part of the neck and throat) to the left and right middle ears. When open, the tubes couple the frog's left and right ears, making them sensitive to audible sounds from all directions. When closed, their ability to pick up ultrasonic frequencies kicks in.
"We said, 'Woah! This is bizarre!'" Feng recalled. "In all textbooks on sound communication and hearing in frogs, it is plainly stated that the Eustachian tubes are permanently open!"
This frog also possesses recessed ears instead of ones located on the body’s surface which may give it its ability to localize sound with amazing precision. When a wooing female starts to sing, male frogs have been recorded leaping directly in her direction with over 99% accuracy. They miss the mark less than 1% of the time. This level of accuracy has never been recorded in any other species of frog.
"On the one hand, I am surprised that any frog can open and close the Eustachian tubes," Carl Gerhardt, professor of biological sciences at the University of Missouri, told Discovery News.
"But on the other hand, I am not too surprised that this frog does it because it is also the first to be shown to have ultrasonic hearing and calls with ultrasonic components."
Discovery News also tells us:
“The frog's unique hearing system is already being used as a model for "intelligent" hearing aids that can spatially separate sounds, process them the way that human brains do, and boost sound signals of interest, such as differentiating background noise from that of a desired conversation.”
Approximately three weeks ago, I wrote about a similar fungus that was threatening the frogs of Prince Edward Island, Canada.
It now appears that a fungus is threatening the frogs of the rainforest. Since many of the frogs that are being threatened are present in only one or two populations, once they have become extinct in that area there is no other population to take from for relocation and/or captive breeding programs.
Frog lovers the world over need to make their voices heard. I will have contact info at the end of the blog.
Hemiphractus fasciatus. It carries its eggs on its back. Photo: Roberto Brenes, via Discovery News
A fungus that appears to prefer the rarest species of frog has emerged in the rainforests of Central America. This fungus seems to be deadlier for rare frogs than common ones. This is leading to a homogenization of the local ecosystem causing changes in the local food chain; harming eco-tourism in Central America; and, hindering medical science.
Amphibians — of which frogs make up the majority — are a vital part of the food chain, eating insects that other animals don't touch and connecting the world of aquatic animals to land dwellers. Without amphibians, the insects that would go unchecked would threaten public health and food supplies.
Amphibians also serve important biomedical purposes. Some species produce a chemical used as a pain reliever for humans; one species is linked to a chemical that disables the virus that causes AIDS.
"This frog species, Hylomantis lemur, was a reasonably widespread species, originally present at five study sites. After the fungus passed through the region, it could no longer be found at any site." Photo: Roberto Brenes, via Discovery News
"Everyone knew that amphibian declines were really bad," said ecologist Kevin Smith, of Washington University in St. Louis. "But it looks like its worse than we actually thought."
Smith and colleagues looked for patterns of extinction in frogs from eight rainforest sites around Costa Rica and Panama. They compiled several years’ worth of data from previous studies, in which scientists had painstakingly surveyed frog diversity both before and after the arrival of Batrachochytrium dendrobatidis (Bd).
Bd has swept through amphibian populations globally in the last decade, often decimating populations. In Central America, Smith said, infections can wipe out half of the species at a given site.
The chytrid fungus coats the frog's skin and makes its pores non-functional. Because a frog relies on its porous skin for hydration and for some of its respiration, the fungus essentially cuts off its water supply and makes it difficult to breathe. In the end, the frog dies from dehydration.
It is not yet clear why the rare frogs are succumbing more frequently than the more common varieties; however, as they disappear so do the roles they fill in the ecosystem.
Tom Rooney, an ecologist at Wright State University in Dayton, Ohio, says that the loss of variety makes it increasingly hard for the species left behind to deal with further environmental damage.
"If you're thinking globally, studies like this are telling us that losing rare species is not a local phenomenon," Rooney said. "If they are disappearing locally, there's a good chance they're disappearing regionally, and local efforts can be even more important."
A CBCtv video discussing the danger the frogs of the world are in:
Sir David Attenborough discusses why frogs and amphibians are so important to any ecosystem.
A fungus that's potentially deadly for frogs has been found in ponds on Prince Edward Island. Prince Edward Island is one of Canada’s scenic jewels – a rugged little island with a beauty carved by nature. (Couldn't resist a little plug for one of my favourite provinces.) Unfortunately, PEI (Prince Edward Island) is not the only place to be hit by the fungal frog-killer, Chytrid. It is just the latest in a long string of places to fall victim to this disease.
Already Golden frogs are extinct; up to 1/3 of the world’s frog species are under threat of extinction; and, 50% of all frog species are in serious trouble.
This crisis began in the 1980s and scientists are saying this has the potential to be the largest mass extinction since the disappearance of the dinosaurs. Surely, a fungus can’t be responsible for all this devastation, can it? Think again…
Chytrid is an infection that is causing problems for frog populations around the world. The fungus, which lives in the skin of the frog, is causing 200 species of frogs to either severely decline or become extinct.
This summer, a team of researchers swabbed 114 frogs at 18 ponds across the island. Unfortunately, over 50% of those swabbed tested positive for chytrid. "Some of the frogs actually go into spasms, sort of like having a seizure," Maria Forzan, a wildlife pathologist with the Canadian Co-operative Wildlife Health Centre, told CBC News last week. She added, "They lose weight very quickly and; within three or four days, basically they're dead."
To date, the fungus is not killing many frogs on PEI. Most of the ponds tested were found to be infected; but, amazingly only one dead frog was found. The frog was severely infected and the team suspect that’s what killed it.
"The fungus doesn't like temperatures that are too hot or too cold, so it might be that the weather will actually work in the favour of the frogs, at least in the Maritimes," said Forzan.
Forzan and a team of biologists from UPEI (University of Prince Edward Island) plan to continue their research in order to determine what damage the fungus is causing the island frogs. Chytrid poses no threat to humans, Forzan hastens to add.
She hopes that the public will help stop the spread of the fungus on the island ponds by taking preventative measures such as: disinfecting their boots after every pond visit; not moving frogs from one pond to the other; and, disinfecting any equipment used, such as nets, after each pond visit.
I'm fortunate to have several passions in my life. I am absolutely an eco-nut. I am always trying to find new ways to reduce, reuse, recycle. We, as a species, have done more harm to this planet in the short time we have been here, than any other catastrophe or happening ever has. It's up to us to fix it.
I care about the environment whether it is as small as a single cell or as large as the universe.
I adore creativity and think we can all do more with much less. This earth has enough resources for us all to live comfortably if we all learn to share. Wasn't that a lesson we were supposed to learn in kindergarten?
I also love the bizarre, unusual, the weird and the strange. Be prepared for the odd "different" blog.
Odorrana tormota is one of only two frog species known to have a concave ear. Researchers believe that its unusual ear structure and high-pitched calls are an evolutionary adaptation to a noisy environment. Photo courtesy of Albert S. Feng, University of Illinois. 
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