Okay, this is definitely one of my favorite articles that I have read so far! How can it even be possible that creatures are living to be over 200 years old! It is also crazy that the one thing that could be killing off this shark is the changing temperatures of the Arctic Ocean. Not humans hunting them, not humans hunting the Greenland Shark's prey, but instead global warming. This global warming crisis could lead to changes in fishing practices and therefore a downward trend for these incredible creatures.
          Easily the craziest part of this article in my opinion is the rate at which this shark grows and matures. First of all, a study has estimated that the Greenland Shark grows at less than one centimeter per year. Compared to an infant human, which grows approximately 1.5-2.5 centimeters a MONTH, it is clear just how slowly the Greenland Shark really grows. However when you compare the lifespan of a human to the Greenland shark, the reason behind the slowed growth is clear. Second of all, the female Greenland shark is expected to not reach sexual maturity until they are nearly 150 years old. I can't even fathom 150 years! After learning these super crazy facts, I began to wonder how the scientists and researchers determined the lifespan of these sharks. There is no way to tag a shark and monitor it over its life, without also living over 200 years, or I guess you could pass down the information for generations, but there is bound to be a mistake.
          The article cleared up this dilemma for me. Scientists were unable to observe countable layers in the vertebrae of the shark because they were too soft for deposits to form. Additionally, researchers were not able to count layers of calcified tissues which tend to grow on the fin scales or other bony structures of a fish, however; Greenland sharks lack these type of fins. A common trait of a Greenland shark is a small, spineless fin which makes the counting process described above, nearly impossible. Researchers have developed a process to determine the age of these sharks by measuring the levels of radioactive carbon-14 fibers in the center of the shark's eye lens. The most recent measurement found that the largest shark measured was estimated to be between 272 and 512 years old. This seems like an incredible gap.
          The most probable reason behind why these sharks are living so long, is believed to be the little expenditure of energy by these creatures. This therefore makes it possible for this creature to maintain its low body temperature and massive size. That however does not exactly answer the question as to what is different about this shark. What is different about this shark which makes it possible for it to live upwards of 500 years? There are tons of creatures in the water right now which expend little energy and maintain a low body temperature. So really, what is different about this shark? This is what is so intriguing about the ocean. There is so little that we really know and understand, and we are constantly learning and growing our understanding of this seemingly bottomless expanse of unknown creatures and the way they live. I would love to learn more about sharks and sea animals like the Greenland shark, but really I would like to know how the organs, and systems of the body can survive the 500 years as well.
         

Comments

  1. I have to agree with you: 200 years is way more than I can fathom. Like, wasn't the second Bank of the United States chartered 200 years ago? Throwback to APUSH, ack! But in all seriousness, that just seems like so long ago that I can’t really connect myself to the events occurring back then. I feel similar about how slowly the Greenland shark grows. Less than a centimeter per YEAR? That’s crazy, and I love how you added this bit about how quickly humans grow in order to add some perspective.

    My big question is, why? Why does this shark grow so slowly? Why does it live so long? What is the benefit of doing so? Based on how climate change is negatively affecting it, I feel like it is a disadvantage, not an advantage.

    It’s really cool how scientists were able to find a way to get a general estimate of the shark’s age, even though the two more common methods could not be used. And I have to agree with you, it seems like a really large gap between 272 and 512 years old. Is there a way they could narrow that down and get a more exact age?

    Like you, I am also curious about what makes this shark so different. Why does it live longer and grow slower if there are plenty of other animals in the ocean that also expend little energy and have a low body temperature? Why is it different? Or is it different? Maybe there are tons of other vertebrate that live just as long and grow just as slowly that we simply don’t know about yet! This shark could be only the beginning! Super cool article!

    ReplyDelete
  2. I too marvel at how long the shark can live and ask these same questions, especially: "Is there a way they could narrow that down and get a more exact age?" I really admired how the scientists were able to get an age estimate using such as creative method, but I have to agree that it is a large gap between 272 and 512 years. I think the scientists are more focused on other areas of research after this regarding the Greenland shark, so they probably won't try to make a more precise age estimate; however, it would be interesting to see how close one could get.

    For my science fair project last year, I investigated ways to determine the age of objects. I found that the size of lichen growing on gravestones was a pretty accurate indicator of the stones' age. Now, of course lichen does not grow in the deep sea and scientists have access to better equipment than my ruler, but perhaps a similar method could be used to determine the age of the sharks. Even if it's not lichen, there are thousands of organisms in the ocean; there must be some that act similar to lichen, growing on other organisms, and therefore could be used to date the sharks. Just a thought! (even if it's kind of a crazy one) :)

    ReplyDelete

Post a Comment

Popular posts from this blog

Gene Loss= Genetic Change??

CRISPR