Antarctic Icefish

Originally published December 2, 2009 (The Manitoban, Vol. 97, No. 16)

It is written (at least it is now): "As you sow procrastination, so shall you reap procrastination…" You should be glad to know, if you haven't guessed already, that I am procrastinating. Right now. Sacrificing valuable study time and perhaps even entire letter grades to tell you about yet another of the under-appreciated creatures inhabiting our planet. I suggest you return the favour (and fulfill the italicised proverb above) by procrastinating about your own studies in order to read this.

Winter is coming and we can learn a lot from the icefish. If you want to impress your friends, I suggest you refer to them as Notothenioids, which is the suborder they belong to. If you'd like to refer to them as a family call them Channichthyidae, but just make sure you can pronounce this stuff before you go making a fool of yourself over it. 

 

There are over 120 described species of icefish living in the frigid Southern Ocean waters surrounding the Antarctic. These fish are primarily benthic (they live on the bottom) and all lack a swim bladder (that thing that helps other fish move vertically in the water column). Buoyancy is instead regulated by deposition of lipids in the tissues, by reduced ossification of bony structures, and reduction in the amount of skeletal elements they possess. 

Icefish are able to survive in the below freezing Antarctic waters (-1.5 to -2.0 C) that are not frozen thanks to salt. How do they do this you ask? Well, I am glad you asked because that is the second neatest thing about these fish. Their body fluids have antifreeze proteins in them that bind to ice crystals, should they begin to form, and prevent them from spreading throughout the body. 

The first neatest thing about icefish is that they have no erythrocytes (red blood cells) or hemoglobin in their blood (you know that protein that carries oxygen to your starving tissues? No big deal...). Aside from being a great statistic to brag to your distant evolutionary relations about--they are the only vertebrates in the world that don't make hemoglobin--it looks really cool because without hemoglobin, blood is colourless! How do they get away without hemoglobin? This is made possible by one of the many mysterious and wonderful properties of water: cold water has higher concentrations of dissolved oxygen, allowing the icefish to meet all their oxygen needs through the skin and at the gills. If only life were so easy for us frigid, pathetic humans, just waiting for the big freeze. 

At least there's hockey to look forward to over the next 6 months!