As you can see, the trawl is pretty long. The big silver pieces are pushed open underwater.
Our final trawls before heading back to Palmer are focused on catching some georgianus icefish.
As you can see, all sorts of interesting and beautiful sea creatures come up in the trawl. Here's a pretty good sized octopus. After the fish that will be used for the study are culled out of the trawl, everything else gets tossed back into the water.
Marine Projects Coordinator, Jamee Johnson and Marine Lab Tech, John Betz pull in a trawl.
This species is different than the aceratus that we have been catching. As you may know by now – there are 16 species of icefish found only in the Antarctic waters. These icefish are the only known vertebrates that do not produce hemoglobin at any point in their lives, including adulthood. There are actually some types of eels, the American eel for example that do not manufacture hemoglobin as juveniles but do as adults. What’s interesting about the georgianus and nine other icefish species is that they do manufacture myoglobin – the iron-based protein that stores oxygen in the muscles. Think word roots – myo/muscle. Like myocardial (heart muscle). Anyway, 10 of the icefish species have no hemoglobin (hem as in blood) but they do have myoglobin. Interestingly, it is only expressed in their hearts and no other muscle. Not even in their pectoral muscles which are the muscles they use to swim and there would be a high demand for oxygen. What’s really interesting about this is that if you trace the evolutionary roots of the 16 species, the myoglobin mutation pops up at different points in the phlogenic tree. What?? Back up. The loss of hemoglobin was a single event in the icefish family tree. A common ancestor lost the ability to produce hemoglobin and all species after that do not have that protein. But losing myoglobin was NOT a single event. It was lost at 4 different points. Meaning…they are not all as closely related in the icefish phylogeny. Some with and without myglobin may be more closely related than two with myglobin.
Here is the phylogenetic tree of the 16 icefish species. As you can see if you trace backwards to look for the most recent common ancestor of any two species you will see some surprises.
Anyone want to offer a hypothesis about the nature of myglobin, its importance, why those with the capacity to express the gene only do so in their hearts. There is still a lot more to say about this so don’t think we’re done here. In the meantime, we will finish up the trawling and begin to head back to Palmer. Tomorrow is launch 2 of the new and improved Fish Spy. We have great plans for her over the next two weeks.
Ryan Wallace is one of the marine techs on ship. These guys are great. The speed, skill, and precision in which they do their work under pretty harsh conditions many times is impressive.
Matt Ulsh is the other Marine Tech on ship. There are a number of women marine techs who work down here as well. Across the board, they are all pretty amazing.