18 February, 2002
SEALS, SEALS, SEALS! SEALS!
There are many marine mammals in the Antarctic coastal waters. These are seals and whales. A few people have seen humpback seals near the southern part of the safe boating area. People on the LM Gould saw Minke and humpback whales while they were on the January cruise. We have seen many seals near Palmer Station. In fact, we often have some seals sleeping on the rocks right outside our lab door!
Seals are predators. They eat other animals in the Antarctic food web. There are six species of seals that appear in the waters around Antarctica: the leopard seal, the fur seal, the crabeater seal, the elephant seal, the Weddell seal, and the Ross seal. We have had visits from the first four species this summer at Palmer Station.
The leopard seal gets its name from its spotted coat. However, it has a sleek head that looks more like the head of a snake! The leopard seal is able to open its mouth to an amazing size! Male leopard seals can be 3 meters long and weigh 300 kg. Female leopard seals are larger, weighing 450 kg and 4 meters in length. Leopard seals eat penguins, fish, krill, and other seals.
Leopard seals in the Palmer area have been known to bite the pointed ends of Zodiacs when the boats are tied up at the dock. So, we have "leopard seal protectors" at the ends of the Zodiacs! There have been cases where leopard seals have attacked and bitten the bow of a Zodiac, causing it to partially deflate! A leopard seal recently showed great interest in scientists diving in the waters off Palmer Station. For that story, please visit the website of the University of Alabama-Birmingham. Look for the story, "No Buddy of Mine", by Charles Amsler, dated December 1, 2001. http://wow.uab.edu/antarctica2001/
The Antarctic fur seal is classified in the family of sea lions and walruses. We are told we can distinguish it from the "true seals" by its external ears and its flippers. Adult males weigh an average of 200 kg, and may be 2 meters long. Females are smaller: they weigh in at much less-55 kg. Antarctic fur seals move quickly on land, and they can be aggressive. We are told to stay out of their way if we see one on land.
Antarctic fur seals have long hair and an undercoat of fur, as well. These provide insulation. The fur seal does not have as much thick blubber as the true seals. The fur seal used to be hunted for its coat, but hunting is not allowed now. Fur seals eat krill, fish, and squid. Sometimes they eat penguins.
The crabeater seal is the most numerous seal in the world. Crabeater seals can be found on the pack ice. When the sea ice comes in to Arthur Harbor and Palmer Station, we see many crabeater seals on the ice.
Crabeater seals eat krill; they do not eat crabs. These seals are slim and fast in the water. Males may be 3 meters long, and weigh 225kg. Females can be 2.7 meters in length., and weigh slightly more than the males.
The Southern elephant seal is the world's largest seal. Males can weigh 4000kg and grow to be 5 meters in length. Females can weigh 900 kg and grow to be 3 meters long. They eat squid and fish, which they catch in deep dives beneath the ocean surface. Elephant seals used to be hunted for their body oil. Hunting is not allowed here now.
Male elephant seals fight to decide who will be the "beachmaster" or head of a harem of females. We have seen young males practice this fighting. We usually have a group of females on the rocks outside our lab building. Sometimes I hear a noise that almost sounds like barking dogs. I know there are no dogs here. When I go outside to check, it's the sound of the females. It looks like they may be talking about space in the lounge!
Here's the math: change all these metric measure to the measurements of length and weight that we use in the United States.
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