Wednesday, August 31, 2016

Entry Three: The Greenland Shark

     The ocean is truly the last frontier; it's amazing that in 2016, there are still secrets yet to be discovered in its depths. Although the existence of Greenland sharks was not one of these secrets, their mind-boggling lifespan was. While scientists apparently suspected it, as Peter Bushnell said in the article, it was only recently discovered that these sharks may live between 272 and 500 years.
     As exciting as it is, the discovery itself doesn't seem likely to have any great impact on the scientific community. Rather, this discovery presents an opportunity for scientists to use their problem-solving skills and perhaps come up with answers that could be applied to other areas of study too. For instance, in order to come up with the number 272, the scientists had to find a way of dating the shark. Generally, one can "count layers of calcified tissues...on a fish's fin scales or other bony structures," but the anatomy of this particular shark did not allow for this method. The scientists were forced to come up with another way of dating the shark: measuring the level of carbon-14 in its eyes. I was very impressed by the scientists' creativity; I knew that carbon dating was used by archaeologists to date artifacts, but would never have thought to use it for this purpose.
     In addition to allowing scientists a chance to flex their creative muscles, this discovery also opened up areas for future study. One of the scientists who worked on this study, Julius Nielsen, now wants to learn more about the Greenland shark, such as how it catches prey and where it mates. I agree that these would be interesting areas of study; however, I am puzzled as to why Nielsen so quickly dismisses the question of how the shark is able to live so long. Nielsen is focused on the behavior of the shark, while another scientist, Mario Baumgart, wants to know the shark's inner secrets, whether it has any "particular quirks or molecular tricks." Personally, I would be like Baumgart and would be more interested in investigating further the mystery of the Greenland shark's lifespan.
     Lastly, I was very interested in the idea that, since the sharks don't reach sexual maturity until age 150, the species could be wiped out by "a century of heavy fishing." To me, this sounds like a huge weakness and I wonder what the purpose is for this extremely delayed maturity. The fact that the sharks don't reproduce until they are so old seems to go against much of what we have learned already in biology regarding survival of the fittest. (I wonder how the Greenland sharks have survived as a species this far!) I think, in addition to exploring what makes the sharks live so long, it would be worthwhile to investigate their birth and death rates and how those are likely to be affected by new fishing practices--the article mentions--may arise from climate change.

1 comment:

  1. I did not get the chance to read this article what I am blown away that a greenland shark can live to be 500 years old!! Not only that but the fact that these sharks are not considered to be at sexual maturity until they ar 150 years old... why would that be? What is the benefit to the species by having such a late sexual maturity? I feel like that would be bad for the species but maybe it plays a role in why they can live so long. How long is their gestation period? Maybe if it is really long because of how long it takes them to mature?