Keep the fish in the terrestrial environment, perhaps an impossible thing. However, not so for the three researchers from McGill University. They just do it in order to reveal the behavioral and physiological changes in the fish. It is important to prove one theory of evolution which states that the first land animals are marine animals that migrated and evolved since 400 million years ago.
|Polypterus senegalus. (Picture from: http://bit.ly/1sVFCeI)|
"I used to see the fins of fish and movement, and thought that it was very interesting and complex," said Emily Standen, who is the lead author of the research report published in the Nature journal, on Wednesday, August 27, 2014.
"Then I think, how a change of fins organ into something that can work on land? This is what makes this research project began," explained researcher who now works at the University of Ottawa.
Standen and her colleagues then took 111 samples Polypterus senegalus, species of fish are running, with the common name senegal bichir or "dinosaur eel". A number of P senegalus was maintained in a terrestrial environment. Maintenance environment consists of gravel with a mesh floor and as high as 3 millimeters of water to prevent the fish experiencing drought. For comparison, the researchers also observed 38 fish samples were allowed to live in the water.
This dinosaur eels have gills at the same lung. They can breathe on land. Sometimes, they also run from one pond to another pond water when dry. However, they did not do it intentionally.
After maintaining for nine months, the researchers then analyzed the movement. They observed 20 fish were brought up on land and 10 who grew up in the water. Researchers also observed changes in order to fish. And it was revealed that the fish are kept in the terrestrial environment changes the way it goes.
"The fish were maintained at ground moves more effectively. They put his foot closer to the middle, they lifted his head up higher, and more rarely slipped," Standen explained as quoted by The Verge on Wednesday, August 27, 2014.
Surprisingly, the behavior is not the only thing that changed. Bone that supports the movement of the fins is also changing shape. Meanwhile, the elongated collarbone. Changes occurred to support the head and fins move more freely.
"This is an important change," Standen said. Animals that live on land requires the neck and head movements are more flexible, more independent in body movement.
This study does have weaknesses. One of them, dinosaur eel does have a kinship with Eusthenopteron, the first marine animals that walk on land. However, in general, this research gives an overview of the evolution of millions of years ago. *** [EKA | FROM VAROUS SOURCES | THE VERGE]
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