****************************************************** BEARS, FISH, AND FOXES ****************************************************** ****************************** BEARS ****************************** __________ QUESTION: Polar Bears are in the Arctic, but are there any bears in the Antarctic? ANSWER from Dr. Michael Castellini on Feb. 5 1995 Luckily, for those of us who work out on the sea ice in the Antarctic, there are no bears! In fact, there are no land mammals of any kind. The seals can stay out on the ice and not have to worry about being eaten. We believe it is for this reason that they do not act very scared when they see us...nothing has ever bothered them up on the ice. It is very different in Alaska where the seals won't let you get very close at all! __________ QUESTION: Why aren't there any polar bears in Antarctica? ANSWER from Terry Trimingham on February 2, 1995: Field Operation Communications Center, McMurdo Station, Antarctica There are no polar bears here in Antarctica because it is just too cold on the continent to support any kind of land animals. It would be fun to see one here, but I don't think he would be able to survive the winter! **************************** FISH **************************** ******* FISH ******* __________ QUESTION: Is plankton the only food source in Antarctica? What could they do for mariculture besides shellfish farming? Would filtering plankton hurt the bigger fishes' food source? ANSWER from Jocelyn Turnbull: The main food source is krill, which is a large plankton and it looks like a shrimp. The krill feeds on smaller phytoplankton (plants). The krill is eaten by fish, whales and penguins. The fish also eat smaller fish than themselves, and the penguins, seals and whales also eat fish. The killer whales (orca) eat penguins too. As to mariculture, we don't think shellfish farming would be very economical. Because the water is so cold, the shellfish, and other things, grow very slowly. They take at least five times longer to grow than in other places. There are lots of fish down here, but no commercial fishing is allowed to protect the fish and other animals. The fish grow very slowly too, so commercial fishing could totally destroy the population. If filtering is done by humans, that is the same as fishing and that would definitely affect the other animals, if it was not controlled. The ecosystem needs all of its components to work properly. If you take out any part of the food chain, you destroy the whole balance. A lot of fish, whales, and crustaceans are filter feeders - that means they only feed on a certain size of plankton. They filter out the water, and keep the plankton in the right size. Since this is a part of the natural ecosystem, it doesn't cause any problems for other animals. __________ QUESTION: Is it true that the only Antarctic fish are Antarctic cod and bloodless or crocodile fish? If so, why is there so little diversity? And are there a lot of these types of fish? ANSWER from Diane Stoecker on January 5, 1995 In the Ross Sea, which is very far south in Antarctica, there are 35 species of fish, most of them are bottom-dwellers. In Antarctic waters less far south, there are probably more species because there are more different types of food. In the Ross Sea (near McMurdo) the most common fish are probably the herring-like "Antarctic silverfish," Pleuragramma antarcticum, and the "bork," Pagothenia borchgrevinki, which lives right under the sea-ice. The large Antarctic cod are less common than these small fish. Although 35 is a lot more than 2 species, the number of fish species is still low in the Ross Sea compared to most warmer waters. This is probably because fish need a special set of adaptations to survive in Antarctic waters, including adaptations that prevent formation of ice crystals in their blood and bodies. Also, in Antarctica, phytoplankton and zooplankton are only abundant during the short summer, and to survive there, fish need to be able to live on very little food and use the food efficiently when it is available. ************ ICE FISHING ************ __________ QUESTION: Do you ice fish in Antarctica? ANSWER from Michael Castellini on January 30, 1995 There are scientists who fish through the ice every year because they are studying the types of fish that live in the Antarctic. They usually put a hole in the ice and then put a big, warm hut over it so that they can work and sleep and eat in their camp. Because all the animals in the Antarctic are protected by laws from hunting and fishing, people do not just fish for them for fun or for food, like on frozen lakes. All the countries in the world that work in the Antarctic have agreed to protect the animals there so that there can be no hunting or fishing. __________ QUESTION: How do animals that live in extremely deep parts of the ocean keep from imploding from extremely high pressure? ANSWER: From Dr. Michael Castellini For an object to implode, there must be an air space inside the animal to be compressed. Water, bone, blood, etc., cannot be compressed. So, for fish, squid, etc., there is simply nothing to collapse. For seals, they actually do implode somewhat each time they dive! They have a very soft chest and the exhale before they dive. Below about 200 ft, their lungs are completely collapsed and their chests are caved in. They carry all the oxygen they need in the blood, so that collapsed lung is not a problem. Penguins are like a submarine; they have a very strong chest and just resist the pressure. ************************************ FOXES ************************************ __________ QUESTION: Do Antarctic foxes live near people? ANSWER from Dr. Michael Castellini on February 13, 1995 Unlike the Arctic, no foxes live in the Antarctic. In fact, there are no land animals at all, except for a few insects and algae, plants, etc., that live in the warmer areas near South America. The continent is mostly just frozen ice and snow. Not much for any kind of animal to eat!