Scientists Sequence Genome Of ‘Living Fossil’ Fish

By | April 18, 2013

Workers at the National Museum of Kenya show a coelacanth caught by Kenyan fishermen in 2001.
Scientists have unraveled the genome of the coelacanth, a rare and primitive fish once thought to be extinct, shedding light on how closely it’s related to the first creatures to emerge from the sea. The coelacanth, a fish that can reach up to 5 feet long and lives in deep ocean caves, had only been seen in fossils and was thought to have gone extinct some 70 million years ago. That was until 1938, when fishermen from the Comoros islands off the coast of Africa captured one in a net. A second coelacanth species was discovered off the Indonesian island of Sulewesi in 1997.

The coelacanth’s genome shows “that the lungfish, and not the coelacanth, is the closest living relative to the ,” according to an abstract of a study published in the journal .”The lungfish-coelacanth question has gone back and forth over the years; the lungfish answer is not new, but this is a much better, bigger data set so it does tip the balance a bit,” researcher John Hutchinson, professor of evolutionary biomechanics from the Royal Veterinary College, “The most striking feature of this ‘living fossil’ is its paired lobe fins that extend away from its body like legs and move in an alternating pattern, like a trotting horse.

Other unique characteristics include a hinged joint in the skull which allows the fish to widen its mouth for large prey; an oil-filled tube, called a notochord, which serves as a backbone; thick scales common only to extinct fish, and an electrosensory rostral organ in its snout likely used to detect prey.

“The analysis of the genome also shows that the coelacanth’s genes evolved very slowly, an apparent confirmation of what paleontologists have long believed — that the fish has changed little in the past 400 million years.

“If you think about it, this might be correlated to the fact that the coelacanth lives in a rather extreme and stable environment,” Professor Kerstin Lindblad-Toh, from the University of Uppsala in Sweden and the Broad Institute of MIT and Harvard, told the BBC.

“It lives several hundred meters down in the ocean, and it may also be in an environment where it doesn’t have a lot of competitors. So maybe it adapted to that environment a long time ago and it doesn’t have a huge need for change,” he said. …

via Scientists Sequence Genome Of ‘Living Fossil’ Fish : The Two-Way : NPR.

2 thoughts on “Scientists Sequence Genome Of ‘Living Fossil’ Fish

  1. Babu G. Ranganathan

    DOES FISH DNA SHOW THEY EVOLVED LIMBS?

    The recent news is that scientists have discovered some snippets of DNA from an ancient fish that can cause mice to grow limbs. This is wrongly being hailed as evidence that fish had developed legs. Isn’t it interesting that the fish they got the DNA from didn’t have legs!

    These snippets of DNA from the fish seem to be “triggering” mechanisms. They can only trigger (“turn on”) genes, such as genes for formation of limbs, but, if the genes for limbs first exist, and since genes for limbs exist in mice then these triggering mechanisms, even if from a fish, will work. None of this means fish evolved legs.

    Imagine an evolving fish having part fins and part feet, with the fins evolving into feet. Where‚Äôs the survival advantage? It can’t use either fins or feet efficiently. These fish exist only on automobile bumper stickers!

    Genetic and biological similarities between species are no proof of common ancestry. Such similarities are better and more logically explained due to a common Genetic Engineer or Designer (yes, God) who designed similar functions for similar purposes in various species. Genetic information, like other forms of information, cannot arise by chance, so it’s more rational to believe that DNA or genetic similarities between species are due to intelligent design.

    The genes already exist for micro-evolution (variations within a biological kind such as varieties of dogs, cats, horses, cows, etc.), but not for macro-evolution (variations across biological kinds such as from sea sponge to human).

    Visit my Internet site: THE SCIENCE SUPPORTING CREATION

    Babu G. Ranganathan
    B.A. Bible/Biology

    Author of popular Internet article, TRADITIONAL DOCTRINE OF HELL EVOLVED FROM GREEK ROOTS

    1. Xeno Post author

      Thanks for the tip Babu. I see that your core beliefs are threatened by this discovery and that you’ve been posting on various web sites besides mine.

      For others, here is the article ( http://www.livescience.com/28797-coelacanth-genome-sequenced.html ) which mentions limb growth in mice from coelacanth DNA. Very interesting. I’ll try to get the source and break it down to be better understood. It doesn’t make sense to me because details are missing. Live Science mentions Nature, but the Nature article I found does not have any information about mouse limb growth ( http://www.nature.com/news/living-fossil-genome-unlocked-1.12809 )

      Regarding your other points: Please understand that the conditions to make a fossil are rare. This is why the fossil record is so incomplete. Most species that ever lived and then became extinct left no fossil evidence. Dust to dust. All the bones are crunched by other animals and nothing identifiable is left.

      There are however, well-preserved fossils found in 2004 on Ellesmere Island in Nunavut, Canada of a fish that had the beginnings of legs. We are talking hundreds of millions of years. The legs don’t just pop on one day.

      The human inability to understand how long a million years is, much less hundreds of millions, is what makes evolution hard to grasp for some people.

      Tiktaalik lived about 375 million years ago. Paleontologists suggest it is part of the transition between non-tetrapod vertebrates (fish) such as Panderichthys, known from fossils 380 million years old, and early tetrapods like Acanthostega and Ichthyostega, which we know from fossils about 365 million years old. So, it appears there was a period of 15 million years to get fish to the first fish-like land animals with four limbs.

      As reported in Nature (April 2006) Tiktaalik roseae, has many features of wrist, elbow, and neck that are akin to those of tetrapods. It belonged to a group of lobe-finned fish called Rhipidistia, which may have been the ancestors of all tetrapods. The Tiktaalik is a mixture of primitive fish and derived tetrapod.

      The tetrapods, by the way, are the vertebrate land animals with four legs and feet. They include amphibians, reptiles, dinosaurs, birds, and mammals. They also include snakes which evolved from animals with four limbs.

      The survival advantage for Tiktaalik’s non-fish features are the ability to move about in shallow muddy water. We know this because of where the fossils were found and because we have examples of fish today that can walk on land. Surprised? Do you know about mudskippers?

      Evolution does necessarily not happen once. It is more like a tree with a lot of dead ends, starts and stops. The same features can evolve at different times, even from different starting animals.

      Now, have a look for yourself at a real walking fish! You can easily imagine that this fish, if it had feet and could move faster, would be able to get away from the lizards that eat it, and it would reproduce more, thus over the next 15 million years, the mudskipper’s fins used for walking could, like the Tiktaalik, develop into what you would call legs.

      With all due respect, science absolutely does not support the theory of creation unless you purposefully misunderstand it.

      [youtube=https://www.youtube.com/watch?&v=FLh4ODMBGJE]

      You said “These fish exist only on automobile bumper stickers!” If you won’t believe your own eyes, I can’t help you. If your eyes are opened now, don’t get too upset. Losing your religion is not dying. You will evolve new ways to spend your time. But first, I’m sure you have many questions. Ask away. I believe there is a friendly supportive community of people who have survived the transition who are willing to help you recover from superstition. Science is fun! There is so much to learn, and you can contribute. You obviously have an active mind, so go get a biology degree and join us!

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