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Monday, September 1, 2014

walking fish ...... fish that can walk and live on land

Oxymoron is a figure of speech that juxtaposes elements that appear to be contradictory. An oxymoron is a compressed paradox: a figure of speech in which seemingly contradictory terms appear side by side. Some examples are : crash landing; benevolent dictator; darkness visible; deafening silence; deceptively honest ...... and ‘walking fish’ ! – but then what appears illogical, could often be proved different by Science and technology.  We know the phrase ‘a fish out of water’ – which describes someone who is uncomfortable in a particular situation – as fishes struggle naturally when they are kept out of water, even for a brief while.

Standen, working with McGill University paleontology professor Hans Larsson and student Trina Du, decided to conduct her study using a primitive African fish called a bichir. Bichirs, sometimes kept as pets, have a body shape similar to the first tetrapods. They can breathe air and they can "walk" on land by propelling themselves with their fins, albeit clumsily.

All in our life, we have read that - Fishes are animals that live and swim in the water, breathe using gills.  They are thousands of varieties – from the smaller ones of gold fish, guppies and mollies kept as aquarium fish – to trouts and like to Ocean charmers like Sharks and Whales; besides there are stranger ones - eels, seahorses, shellfish, cuttlefish, starfish, jellyfish and more – which by some definition are not fishes.  By some accounts, there are more than 32,000 described species of fishes, more than all the amphibians, reptiles, birds, and mammals combined. Fishes are an important food resource worldwide, and fishing pressure has caused many fish stocks to crash or be at risk.

Fish are abundant in most bodies of water. They can be found in nearly all aquatic environments, from high mountain streams. Fish have had a role in culture through the ages, serving as  religious symbols, and as the subjects of art, books and movies. Raising fish on land seems like the sort of idea not sane people will have. But for three McGill University researchers, it made perfect sense. How else would you find out what behavioral and physiological changes might have taken place when fish first made the move from sea to land over 400 million years ago?

"I used to look at fins and their motion, and I always thought it was so interesting and complex," says Emily Standen, lead author of a study published in Nature today, and an evolutionary biomechanics researcher who now works at the University of Ottawa. "And then I thought, wow, how does that change from a fin to something that might work on land? That’s how this project started."  Standen and her colleagues took 111 juvenile Polypterus senegalus — a fish species that goes by the common name Senegal bichir, or "dinosaur eel" — and raised them for eight months in a terrestrial environment. This environment consisted of mesh flooring covered in pebbles and just 3 millimeters of water — a precaution that, combined with water misters, prevented the fish from drying out. The researchers also formed a control group using 38 fish growing up in their usual aquatic environment.

"We used high-speed video to analyze their movements at the end of the eight-month period," Standen says who added "Fish raised on land walk with a more effective gait."  "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.

For a commoner, it would make no sense as to why should somebody try to make a pure water creature live and walk on land – is it cruel is what readily comes to mind .... but for Scientists experiments are far fetched as Standen says it is exciting to think that we can use experiments on living animals to make inferences about what might have happened to physically similar animals during large scale evolutionary transitions.

With regards – S. Sampathkumar.
1st Sept. 2014.

With inputs from BBC and

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