Endangered dolphin with broken blowhole learns to mouth-breathe

Coming up for air

Steve Dawson, University of Otago

By Alice Klein

Not just a pretty face? A dolphin has learned to breathe through its mouth after developing a faulty blowhole, highlighting the animal’s ability to adapt.

The adult Hector’s dolphin (Cephalorhynchus hectori) was discovered in January 2014 off the coast of Christchurch in New Zealand.

Steve Dawson at the University of Otago in Dunedin, New Zealand, and his colleagues were studying the endangered species as part of a long-term conservation project, when they noticed unusual behaviour in one member of a group of seven.

Each time the dolphin surfaced, it approached at a steep angle and lifted its head higher out of the water than normal. The blowhole stayed shut while its mouth opened wide and made a sound consistent with sucking in air.

Dolphins were not thought to be able to breathe through their mouths. To do this, a dolphin would need to move its larynx from the usual position to allow the respiratory and digestive tracts to communicate, says Dawson.

The animal probably learned to do this after its blowhole became blocked by a foreign object or injury, or because the muscles around it didn’t work properly, he says.  “We think this dolphin has found a workaround to what is most likely a pathological problem.”

Continued  

Why lizards have bird breath: Iguanas evolved one-way lungs surprisingly like those of birds

Date:

November 17, 2014

Source:

University of Utah

Summary:

Biologists long assumed that one-way air flow was a special adaptation in birds driven by the intense energy demands of flight. But now scientists have shown that bird-like breathing also developed in green iguanas – reptiles not known for high-capacity aerobic fitness. The finding bolsters the case that unidirectional bird-like flow evolved long before the first birds.

Continued ...

Dinosaur breathing study shows that noses enhanced smelling and cooled brain

Date:

October 14, 2014

Source:

Ohio University

Summary:

It's been millions of years since T. rex took its last breath, but a team led by Ohio University scientists is breathing life back into dinosaurs using high-powered computer simulations to model airflow through dinosaur snouts. The research has important implications for how dinosaurs used their noses to not only breathe but to enhance the sense of smell and cool their brains.

Continued ...

Unidirectional breathing of certain reptiles seems to have caught the attention of scientists all over the world. Research and studies bring out a new facet of these beings - via Herp Digest

by Ewen Callaway. Mar 4, 2014, The New York Times, Reprinted in Deccan Herald, Australia.

A lizard captures oxygen from air, both when inhaling and exhaling – a feat normally associated with birds. Many scientists believe birds developed the quality to cope with the enormous requirements of energy needed to take flight, and the discovery of “unidirectional breathing” in the Savannah Monitor Lizard raises questions about when and why the trait first evolved.

“To go and find a similar air - flow pattern in animals as distantly related (to birds) as monitor lizards is mind blowing,” says Mathew Wedel, an evolutionary biologist at Western University of Health Sciences in Pomona, California, who was not involved in the discovery.

Mammals and manyother vertebrates breathe tidally, which means that air travels into the lung to gas - exchanging cavities called alveoli and then back out via the same path. Not birds, which store some of the air they inhale in specialised sacs. When they exhale, oxygen is extracted from this air.

Reptile studies

In 2010, a team led by Colleen Farmer at the University of Utah in Salt Lake City reported that alligators and other crocodile-like animals too, practise unidirectional breathing. The discovery hinted that dinosaurs might have also breathed the same way. But Wedel says that “it wasn’t super surprising that crocs might be a bit bird like,” because their lungs resemble those of birds.

Now a team led by Farmer and her colleague Emma Schachner, an evolutionary biologist at the same institution, report in Nature that Savannah Monitor Lizards (Varanus exanthematicus) use the same breathing mechanism.

Monitor lizards are a group of 70 or so species that includes Komodo Dragons, the largest lizards on Earth. On the surface, their lungs look like they would use breathing, Schachner says. “When you pull the lungs out it just looks like a bag with chambers. It doesn’t look anything like the bird lung.” But computed tomography (CT) scans revealed a large chamber, with a series of up to 11 brachial tubes branching off in parallel and linked to one another via perforations – a set-up that could enable one-way flow.

To test this possibility, the researchers dissected the lizards’ lungs and filled them with water containing suspended spheres, to better track how the water flowed. The water flowed tidally through the large chamber, but unidirectionally in the smaller brachial tubes. Schachner’s team confirmed that air followed these patterns during breathing as well by implanting sensors in the lungs of five lizards and measuring air flow as the animals breathed.

The discovery of unidirectional breathing in monitor lizards could either mean that the trait evolved in the common ancestor of birds, crocodiles and lizards – an animal that lived roughly 270 million years ago and resembled an Iguana – or that the feature evolved independently in each evolutionary branch, Schachner says. To determine which scenario is correct, Schachner’s team plans to study the breathing patterns of more reptiles, such as Iguanas, Geckoes and Bearded Dragons.

Questions asked

Her team’s study also raises questions about why unidirectional breathing developed in the first place. Farmer has hypothesised that it helps animals obtain oxygen while they’re holding their breath because unidirectional breathing allows more oxygen to be extracted from air - something that many lizards do when startled.

Crocodiles can hold their breath for about 20 minutes, and ancient marine reptiles may have found the trait useful for long dives, Schachner says. The trait could have also been an adaptation to lower oxygen levels on Earth, she says. During the early Triassic era, 250 million years ago, oxygen made up 12% of air, compared with 21% today.

“It might explain something about why monitor lizards are so successful,” says Wedel. These lizards get more oxygen from air than any other reptile and they live in environments ranging from parched desert to tropical forest. “Who knows when the next asteroid hits, maybe monitor lizards will inherit the Earth,” Wedel says.
Schachner believes that no one found unidirectional breathing in lizards because the trait is so hard to measure, especially in wild animals.

Wedel hopes the discovery by Schachner’s team will inspire others to eschew conventional wisdom. “Now everybody who wakes up tomorrow and reads this paper will look at familiar organisms with a bit of curiosity and mistrust.”

Lizards breathe more efficiently than humans do - via Herp Digest

by Deborah Netburn, 12/17/13, Sttuf.co.nz

Little-known fact: When it comes to extracting oxygen from the air we breathe, we humans are just OK.

Birds are more efficient breathers than we are. So are alligators and, according to a new study, monitor lizards, and probably most dinosaurs were as well.

Humans are what are called tidal breathers. When we breathe in, fresh air moves into our lungs along progressively smaller airways, eventually ending in little sacs called alveoli, where our bloodstream picks up oxygen and deposits carbon dioxide. Then the "old" air moves out of our lungs along the same path it came in.

But birds, alligators and monitor lizards are "unidirectional" breathers. After the air moves into their lungs, it begins to follow a system of tubes similar to arteries, capillaries and veins. In this system, the air moves through the air tubes in only one direction.

And, it turns out, their system is more efficient at extracting oxygen from the air than ours is.

Scientists discovered that birds are unidirectional breathers in the first half of the 20th century, after researchers noticed that pigeons breathing the sooty air of train stations showed just one black area on the lung. If the pigeons breathed like we do, scientists would have expected the entire lung to be black.

"The fact that only one part of the bird lung was dark suggested the air was flowing in one direction and that the first part of the lung to receive the contaminated air was filtering the particles," said Colleen Farmer, an associate professor of biology at the University of Utah.

It isn't that surprising that birds have developed a more efficient breathing system. Scientists hypothesize it may have evolved to help them support their high metabolic rates, or to help them survive when they fly at high altitudes, where oxygen is scarce.

But in 2010, Farmer published a study showing that alligators are unidirectional breathers as well.

"That's when I realized it had to have a function other than supporting the high metabolic rates associated with birds," she said. "I knew cold-blooded animals spend about 80 per cent of their lives holding their breaths - and so I formulated the hypothesis that this breathing would be important for mixing gases in the lungs during a breath-hold."

On Wednesday, Farmer published a study in the journal Nature that shows monitor lizards are unidirectional breathers as well. She believes that further studies will show that all lizards and snakes are also unidirectional breathers.

"(Unidirectional breathing) appears to be much more common and ancient than anyone thought," she said in a statement.

The scientists are still not sure exactly when unidirectional breathing first developed, but if it all evolved from one ancestor rather than concurrently, it is possible there have been unidirectional breathers walking the planet for 270 million years - 100 million years before the first birds and 20 million years earlier than anyone thought.

And although it is impossible to directly study whether extinct animals like dinosaurs were unidirectional breathers, Farmer said that since alligators, birds and probably most lizards breathe this way, it's likely the system was inherited from an ancestor the dinosaurs shared as well.

Farmer said the next step in her research is to determine just how common unidirectional breathing is or was.

"We want to look at a bunch of lizards and snakes and turtles and amphibians," she said. "We have a lot of work ahead of us."