December 13, 2001

Hi Class,

It is another stormy day with no aircraft flight. So some of the scientists and engineers that I work with and I decided to find out about the aquarium on the bottom wing of the Crary Science Laboratory where we work on the base at McMurdo. Do you remember Ali from the fishing trip that I took earlier in the week? Well, she took us on a tour of the aquarium and showed us a number of the marine (ocean) life specimens on display at the aquarium. First she showed us the display tank in the aquarium marked "touch tank". I thought that having a touching tank when there were no children around was a bit unusual, but I guess even some adults are excited about touching some of the really unusual creatures that live under the ice surrounding the base at McMurdo.

Ali explained that the aquarium was not set up to permanently display marine animals for people to see, but it is rather a temporary facility for holding fish used in protein and DNA experiments and for holding invertebrates accidentally caught in fish traps set in deep areas below 400 meters (1312 feet). These unintended catches of invertebrates are referred to as "by catch". You may wonder why they don't just release the invertebrates right on the spot when they bring up the traps. The problem is that these bottom dwelling (benthic) creatures would not know how to get back to the bottom and would perish somewhere in the upper portion of the ocean. If my schedule allows, Ali may take me on one of these trips where she brings up bottom traps so that we can see just what happens.

Ali first showed us some of the unusual creatures in the touch tank. All of these animals are benthic and live with very little light. The first thing that caught our eye was an octopus. The octopus was not at all shy and, if anything, appeared to enjoy being photographed. As we watched he would extend his arms and move about. Ali said that he was checking the currents in the tank. On closer inspection of another octopus, we could see the suction cups on the under side of the octopus's tentacles and nearby we saw yet another more unusual octopus. We couldn't help but notice the large starfish. My fingers give you some idea of the size of the starfish.

We next looked at a Giant Antarctic Isopod. This may surprise you, but it is a relative of the tiny sow bugs that you find outside in damp areas like under stones and mats near your house in the summer. This isopod grows quite large in these waters where the creature's metabolism is kept quite low because of the low temperature. They can grow up to 8 inches in length! In fact, Ali says many of these creatures that inhabit the cold, dark waters beneath the ice grow much larger than their relatives that live in warmer waters. Soon we were attracted to the curious looking brittle star. Ali says that the brittle star actually snatches prey with an extended arm and hauls the food to its mouth.

Near the brittle star we noticed some sea spiders. Some sea spiders have leg spans up to 20 inches wide. They can occur as deep as 4,500 meters (nearly 2.8 miles). Next we saw a feathery animal called a crinoid and another crinoid with a shrimp clinging to it. Crinoids are close relatives of starfish. Nearby, we saw a sea urchin which partially covered itself with an empty clam shell. Ali told us that these sea urchins typically add different items to cover themselves. Why do you think they do this? Another curious invertebrate looked to me to be almost a fruit until you turn it upside down, where you can see it has a foot like a snail. Ali also showed us a cnidarian colony. It looked to me to be more of a plant than an animal, but cnidarians are classified as animals and the colony is composed of many individuals doing different functions much like some kinds of coral.

Then we started looking at some of the unusual fish swimming around the tank. First there was the alligator fish (near the center of the photo). Some other fish with large heads that can also be seen in the photo are called Plunder Fish. Ali explained that most Antarctic fish are closely related. These fish were essentially isolated as Antarctica drifted away from the other southern continents and kept separated from other fish types by the currents and extreme temperatures of the southern ocean. In the absence of other fish types, this fish family evolved into a variety of different looking fish that fill many niches. Ali next showed a tank containing a fish called an eel pout. The eel pouts sure look like eels, but they are not. We also saw some tanks containing Antarctic Cod but we already knew about them from the fishing trip that we took to the ice house earlier in the week.

Some of these fish have been found to be able to naturally secrete an antifreeze that allows them to hide just under the ice and in small holes and pockets in the ice without getting frozen into the ice.

Ali explained that many of the fish such as the cod and eel pouts are used in studies of fish protein, but some of the other fish and all of the invertebrates are not used, and have just been captured as "by catch". She said that these animals would be returned to their natural habitats by divers in the near future and that they would be kept in the lab only until they could be safely released.

I hope you have enjoyed our tour of the aquarium. To learn more about the habits of the marine organisms that you just saw and to see even more oceanic life surrounding Antarctica you can visit the Scripps Institution of Oceanography.

Robert Swift