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  • The dead coming back to life sounds scary.

  • But for scientists, it can be a wonderful opportunity.

  • Of course, we're not talking about zombies.

  • Rather, this particular opportunity came in the unlikely form

  • of large, slow-moving fish called the coelacanth.

  • This oddity dates back 360 million years,

  • and was believed to have died out during the same mass extinction event

  • that wiped out the dinosaurs 65 million years ago.

  • To biologists and paleontologists, this creature was a very old and fascinating

  • but entirely extinct fish, forever fossilized.

  • That is, until 1938 when Marjorie Courtenay-Latimer, a curator at a South African museum,

  • came across a prehistoric looking, gleaming blue fish hauled up at the nearby docks.

  • She had a hunch that this strange, 1.5 meter long specimen was important

  • but couldn't preserve it in time to be studied and had it taxidermied.

  • When she finally was able to reach J.L.B. Smith, a local fish expert,

  • he was able to confirm, at first site, that the creature was indeed a coelacanth.

  • But it was another 14 years before a live specimen was found in the Comoros Islands,

  • allowing scientists to closely study a creature

  • that had barely evolved in 300 million years.

  • A living fossil.

  • Decades later, a second species was found near Indonesia.

  • The survival of creatures thought extinct for so long

  • proved to be one of the biggest discoveries of the century.

  • But the fact that the coelacanth came back from the dead

  • isn't all that makes this fish so astounding.

  • Even more intriguing is the fact that genetically and morphologically,

  • the coelacanth has more in common with four-limbed vertebrates

  • than almost any other fish, and its smaller genome is ideal for study.

  • This makes the coelacanth a powerful link between aquatic and land vertebrates,

  • a living record of their transition from water to land millions of years ago.

  • The secret to this transition is in the fins.

  • While the majority of ocean fish fall into the category of ray-finned fishes,

  • coelacanths are part of a much smaller, evolutionarily distinct group with thicker fins

  • known as lobe-finned fish.

  • Six of the coelacanth's fins contain bones organized much like our limbs,

  • with one bone connecting the fin to the body,

  • another two connecting the bone to the tip of the fin,

  • and several small, finger-like bones at the tip.

  • Not only are those fins structured in pairs to move in a synchronized way,

  • the coelacanth even shares the same genetic sequence

  • that promotes limb development in land vertebrates.

  • So although the coelacanth itself isn't a land-walker,

  • its fins do resemble those of its close relatives

  • who first hauled their bodies onto land

  • with the help of these sturdy, flexible appendages,

  • acting as an evolutionary bridge to the land lovers that followed.

  • So that's how this prehistoric fish helps explain the evolutionary movement

  • of vertebrates from water to land.

  • Over millions of years, that transition

  • led to the spread of all four-limbed animals, called tetrapods,

  • like amphibians, birds, and even the mammals that are our ancestors.

  • There's even another powerful clue

  • in that unlike most fish, coelacanths don't lay eggs,

  • instead giving birth to live, young pups, just like mammals.

  • And this prehistoric fish will continue to provide us with fascinating information

  • about the migration of vertebrates out of the ocean over 300 million years ago.

  • A journey that ultimately drove our own evolution, survival and existence.

  • Today the coelacanth remains the symbol of the wondrous mysteries that remain

  • to be uncovered by science.

  • With so much left to learn about this fish, the ocean depths and evolution itself,

  • who knows what other well-kept secrets our future discoveries may bring to life!

The dead coming back to life sounds scary.

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B2 TED-Ed fish land prehistoric creature transition

【TED-Ed】The coelacanth: A living fossil of a fish - Erin Eastwood

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    稲葉白兎 posted on 2014/11/30
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