****************************************************** SEA CREATURES ****************************************************** ****************************************** SEALS ****************************************** ********************** ADAPTATION TO COLD ********************** __________ QUESTION: What kind of adaptations occur in seals because of changes on a cellular level? ANSWER from Diane Stoecker on December 6, 1995: Although Antarctic invertebrates and fish have many molecular adaptations to the cold and to prevent freezing, in seals and other warm-blooded animals, most of the adaptations are anatomical or physiological--they have insulating blubber and specialized circulatory systems that keep their vital organs from coming in contact with extreme conditions. I'm sure there are some subtle molecular adaptations in enzymes, etc., but most of the adaptations are in the body of the seal and in its behavior. *********************** ATTACKS ON PENGUINS *********************** __________ QUESTION: Have you ever seen an attack on a penguin by a leopard seal? If so, what was it like? ANSWER from Dr. Michael Castellini on Jan. 27 1995 I have never seen a leopard seal take a penguin, but many of my friends have seen and photographed it. Usually, the penguin just goes limp, like it is trying to play possum. We do not know if this is some kind of defense, or if it is shock. In any case, the seal usually grabs the bird and shakes it violently to try to kill it and then shakes it even more to literally shake it apart. I have even had friends chased across the ice by leopard seals...they must have thought them to be a really big penguin! ******** BABIES ******** __________ QUESTION: Have you ever seen the birth of a Weddell pup? ANSWER from Michael Castellini on January 12, 1995 Yes, I have been able to watch 3 or 4 pups being born on the sea ice near McMurdo station. The mothers come up onto the ice about 1 week before they give birth and just rest. The birth is very fast, it just takes a few minutes. The pup is wet, but has a very good fur coat, so even though it is very cold (October temps are about -25C), the pup dries out quickly and then stays near the mother to keep warm. They start to nurse after about 12 hours. The birth weight is about 30 kg and they grow quickly to over 100 kg by 5 weeks of age! __________ QUESTION: Do you have medical care for sick baby seals? ANSWER from Dr. Michael Castellini on January 1995 In the field, at the sites where the animals are being born, etc., we do not have the ability to do anything with sick animals. Many, many animals are sick and injured; they die at these locations. It is all part of survival of the fittest and strongest. Of course, if the animals are in a lab or a study pool at an aquarium, then there are many doctors and others that can care for sick or injured animals! __________ QUESTION: Do seals kill baby seals? ANSWER from Dr. Michael Castellini on January 25, 1995: The only seal that routinely kills other seals would be the leopard seal. In this case, the leopard seal is merely hunting. They also eat fish, penguins, etc. There are not any cases that I know of where seals within a single species kill the young of other animals. Many young seals and sea lions are killed on the rookeries, but this is because they accidentally get caught in stampedes, etc. ****************** HOLDING BREATH ****************** __________ QUESTION: How long can seals go without breathing? ANSWER from Polly Penhale on January 12, 1995 Different seals have different abilities to go without breathing. The record for the Antarctic Weddell seal is 80 minutes, but this is very rare. Only about 3% of their dives exceeds the typical 20-25 minute dive. Northern Elephant Seals routinely dive 30-35 minutes. Harbor seals typically dive 4-8 minutes, while the Galapagos Island seals only dive about 3 1/2 minutes. ANSWER from Michael Castellini on January 25, 1995 Some seals can hold their breath for a very long time, others not so long. Currently the record is over 90 min for Weddell seals and over 120 minutes for elephant seals! Not all dives are for so long however; most are much shorter, about 10-15 min. That is a long time for you, of course, but for a seal it is pretty easy. They can do this by keeping a lot of oxygen in their blood and muscles, much more than you or I can carry. **************** LEOPARD SEALS **************** __________ QUESTION: How many teeth do leopard seals have? ANSWER from Dr. Michael Castellini on Jan. 13, 1995 Leopard seals have lots of BIG teeth, but no more than most mammals, about 30-40. They eat fish, penguins and seals. __________ QUESTION: Besides penguins, what else to leopard seals eat? ANSWER from Michael Castellini in February, 1995: Leopard seals eat a variety of animals. As you mentioned, they do eat penguins. They also eat other seals and fish. They have also chased humans both in the water and out on the ice and have bitten a few in the process, but have never actually seriously hurt any human. Like all seals, they will eat a lot of different things, but they are unique with their diet of warm-blooded species like penguins and other seals. ******************** MATE RECOGNITION ******************** __________ QUESTION: In a group of seals, how does the male leader tell which females are his? ANSWER: Deane Rink, Live From Antarctica field producer, on January 14, 1995: This is a tough question and I am only making a guess because our seal experts have gone for the year. I think the lead male seal among Weddell seals chooses his harem, or group of females with which to mate, and the secondary males have to be content with what's left over. Males compete by bullying each other and bellowing, to establish who will be the male leader. But I'll bet the females have something to do with this in a subtle understated way as well. Just a guess. ******************** TIME OUT OF WATER ******************** __________ QUESTION: How long can seals stay out of the water without diving? ANSWER from Polly Penhale on January 12, 1995 One could turn this question around and ask "Why do seals need to go INTO the water"? Looking at the Weddell seal here in Antarctica, we see that they live just fine on the sea ice. There are no predators, so there is no danger for them. This is unlike in the Arctic where polar bears could be a danger. What the Weddell seal does go into the water for is to feed on fish. The Weddell seal comes on the sea ice to breed and the adult females spend about 4 weeks on the ice during this time. During breeding, the females fast for the entire time. They nurse the pups without feeding, and the pups grow from a birth weight of about 30 kg to 120 kg at weaning. Seal milk has a fat content of about 40%, which is very high in the mammal world. ANSWER from Dr. Michael Castellini on January 25, 1995 Seals can stay out of water for as long as they like, they do not need to be in the water to live. Of course, they must go to the water to travel and to hunt for food, so there is some limit. Some seals, like the elephant seals, can stay on the beach for over 4 months and in that time do not eat or drink! They really know how to diet! ***************************************** WHALES, DOLPHINS, AND KRILL ***************************************** ************************ WHALES AND DOLPHINS ************************ __________ QUESTION: Are there any whales or dolphins in Antarctica, and if so, how do they live and what do they eat? ANSWER: From Deane Rink on December 18, 1994 There are a few different kinds of whales in the Antarctic oceans. As you may know, some whales have teeth and feed on krill (shrimp-like crustaceans) and fishes; other whales have filtering systems in their mouths and feed on plankton and algae in the water column. I have seen killer whales (orcas) cruising the sea ice edge looking for penguins. When cruising the waters of the Antarctic Peninsula, I have seen humpbacks and Minke whales. Antarctic oceans are the breeding grounds for many whale species. There are probably dolphins in the southern oceans as well, but I haven't personally seen them nor heard about them. __________ QUESTION: Are killer whales in the areas you've been studying? ANSWER from Dr. Michael Castellini on January 12, 1995: Yes, there are killer whales in the area where we work, but only in the places where the ice ends and the ocean begins. The Weddell seals are much better divers than killer whales and can breathe through smaller holes. So, the seals can get into areas of thick and almost solid ice, where the whales cannot follow them. However, penguins and whales occur almost side by side near the open water off the edge of the ice. I have seen both of them swimming right next to each other. Some whales eat only fish and others eat only penguins and seals. Maybe the seals and birds know which is which! ************** KRILL ************** __________ QUESTION: Who is harvesting krill and for what purpose? Are there any restrictions or management policies in place? ANSWER from Dr. Michael Castellini on January 16, 1995 Krill are fished for two purposes. The Japanese and others are very interested in trying to find out some way to make krill edible for humans. Right now, there is no way that we find them very tasty at all. They are also harvested to make fish meal to feed livestock, etc. There are many fishing regulations regarding the Antarctic, and it is fairly well controlled if you want to fish below 60 degrees south. However, if you fish north of there, it is not so well regulated. I don't think that over harvesting of krill is too much of a problem at this time, but many people are paying attention to it.