Wednesday, February 29, 2012

NO HEMOGLOBIN NECESSARY

The mackerel ice fish, also known as the crocodile ice fish due to its teeth and elongated head, is very unique among fish. It is also unique among the entire group of vertebrates. The mackerel ice fish is the only vertebrate that lacks hemoglobin. First recorded in 1954, the mackerel ice fish has nearly colorless blood due to this lack of hemoglobin. Hemoglobin is found in red blood cells and is what allows vertebrates to carry oxygen in their blood. Without hemoglobin, oxygen cannot attach. So how do these fish get oxygen to through their bodies?

Part of their name “ice fish” is given because these fish live in the frigid waters of Antarctica. The solubility of gases increases as the temperature decreases thus making the extremely cold ocean water where these fish live exceptionally oxygen rich. The salt in the water of the ocean allows the water to reach temperatures far below the normal freezing point of water without turning into ice. The colder the water, the higher the solubility of oxygen gas. Many animals would freeze to death from their blood freezing at such a temperature. However the mackerel ice fish has a chemical “antifreeze” in its blood that prevents ice crystals from forming and allows the fish to live comfortably at extremely low temperatures. A high oxygen concentration in the water is important because the mackerel ice fish’s lack of hemoglobin lowers its oxygen-carrying capacity to less than 10% of that in closely related red-blooded species of fish. However, several anatomical modifications have occurred over time and the ice fish have evolved their body structures to adapt to their environment.

Ice fish have a denser concentration of veins and arteries supplying their high oxygen demand tissues. They also have large capillaries and blood volumes that are four times that of closely related red-blooded fish. Another feature of their body that assists with high oxygen delivery is the size of the heart. Ice fish have large hearts that beat almost twice as fast as their relatives and allow them to circulate a lot of blood very quickly. The ice fish also has a rather low metabolic rate and thus its need for oxygen is lower than that of other fish. It has also been speculated that they are capable of absorbing some oxygen directly through their skin.

I could not find any current research studies involving these fish, however I’m sure there are many interesting studies that could be done with them.

http://eol.org/pages/206610/overview


Posted By Erica Bonnell(1)

6 comments:

  1. I remember learning about Ice fish in one of my biology classes last year. They are truly fascinating creatures. They are also a great example of how animals adapt to their environment. Something i learned here that i didn't know before is that in cold water, gases are more soluble. A question i have for scientists who study this fish is why are you so interested in this particular fish? Is there something we can use from the way it functions or are you just fascinated by it because we, as human are not capable of it.



    Posted by: Jen Silva(3)

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    1. It really is a cool fish. I actually first heard about it in my Chemistry class when we were learning about gas solubility. It's a great example of the temperature to solubility relationship because it shows how, with colder water, creatures are able to adapt to the significantly higher oxygen concentration.

      Posted By Erica Bonnell (1)

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  2. This is an example of the truly amazing adaptability of animals to their environment. With the way our bodies work and circulate oxygen, its hard to imagine that it can happen any other way and the animal can survive. I also enjoy reading about cases like this where simple chemical principles that we learned long ago - like diffusion and gas solubility, play a large role in organismal function on the macroscopic scale. I am curious about this fish, though. With this anti-freeze quality that it has in its blood, is it safe for human consumption? Are they hunted for food or just studied?

    Posted by Laura Moro (2)

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    1. I actually did find a website on what to cook icefish with. It's a very light fish and so most of the recipes are in a light sauce with veggies. I couldn't find anything about it being cooked differently so I'm assuming that it is perfectly safe for human consumption when cooked the same way as other fish.

      Posted By Erica Bonnell(1)

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  3. We just learned about the ice fish in my biology class. It is honestly fascinating to see how a species can alter itself so drastically over time in order to survive in certain conditions.

    Taylor Pirog

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  4. I remember the ice fish from biology class also, I believe professor houlihan covered ice fish with me also. It was shocking I remember to hear that a creature with blood could survive without hemogolbin. It's one of those things that nature continues to surprise us. We still continue to find new discovers that may one day help us in the future. Like the ice fish.

    Posted By Andy Zou

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