Scientists raise air-breathing fish on land to test evolution

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in science on (#2SGP)
story imageAmong the more interesting aquatic species on our earth is Polypterus senegalus ("Bichir"), a modern African fish that has lungs for breathing air, and stubby fins. It can use the to pull itself along on land for short periods of time. That makes it an good candidate for research into previously unknown aspects of evolution. So scientists have raised a bunch of them out of water for eight months to better understand how ancient creatures may have transitioned to life on land. Have a look here for a picture of the species.1
"The researchers discovered the bichir raised on land were dramatically different than those raised in water. The land-raised fish lifted their heads higher, held their fins closer to their bodies, took faster steps and undulated their tails less frequently and had fins that slipped less often than bichir raised in water. These land-based fish also underwent changes in their skeletons and musculature that likely paved the way for their changes in behavior."
The Bichir is a pretty interesting fish. From Wikipedia, "Bichirs possess paired lungs which connect to the esophagus via a glottis. They are obligate air-breathers, requiring access to surface air to breathe in poorly oxygenated water. Their lungs are highly vascularized to facilitate gas exchange. Deoxygenated arterial blood is brought to the lungs by paired pulmonary arteries, which branch from the fourth efferent branchial arteries (artery from the fourth gill arch), and oxygenated blood leaves the lungs in pulmonary veins. Unlike most lungfish and tetrapods, their lungs are smooth sacs instead of alveolated tissue. Bichirs are unique in that they breathe using a recoil aspiration."

1 So, a bichir is worth a thousand words? Sorry.
[2014-09-17 17:54: Typo fixed: bichir, not bichr. And definitely not bitcher.]

the Verge (Score: 2, Informative)

by zafiro17@pipedot.org on 2014-09-17 12:25 (#2SGQ)

Just noticed the Verge covered this too, and very well. There are some great quotes from that article.

http://www.theverge.com/2014/8/27/6074855/this-is-what-happens-when-you-raise-fish-to-walk-on-land
As it turns out, growing up on land really does change how a fish walks.

"Fish raised on land walk with a more effective gait," Standen says. "They plant their legs closer to the body's midline, they lift their heads higher, and they slip less during that walking cycle." The fish raised on land were also generally more consistent in the way they walked than their aquatic counterparts. But their behavior wasn't the only thing that changed. For example, "the bones in the pectoral girdle - the bones that support the fins - changed their shape," she says. "And their clavicles became elongated." Most changes that occurred were ones that gave their heads and fins more room to move around.

"It's an important change, because if you think of a terrestrial lifestyle," Standen explains, "you actually need a neck on land because you're stuck on this plane, and you need to have more head motion that's independent from the body."
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