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Studying seals is slippery work

Don't let their size and awkwardness on ice fool you. They're fast. And they aren't the cuddly kind you see in theme park shows.

Greetings from the southern Ross Sea. We have encountered the toughest ice on the trip. The Nathaniel B. Palmer, our noble icebreaker, has had to turn around two or three times because we just couldn't make any headway. When the Palmer gets stalled, we try to find lighter ice. This morning, our helicopter pilots helped us find the best route. At one point, it took us a couple of hours to go 100 yards.

It is not just the thickness or hardness of the ice that gives an icebreaker fits, but how much the ice pack is compressed. When high winds blow the ice toward shore, the ice pack compresses like a giant jigsaw puzzle. The pressure on the ice means that when the icebreaker pushes up against it, the ice has nowhere to go to move out of the way, and it doesn't budge.

We've had 30 to 40 mph winds during the past 72 hours, and they helped to compress the pack. They also created a wind chill that made the temperature feel like minus 4 degrees instead of 28. The past couple of work days on deck have reminded us that we are in the Antarctic.

The weather has less impact on our fish sampling program than on our seal biologists, who must fly to cover enough ground to get a good seal census. As I mentioned in my first report, there are several related projects working on the Antarctic pack ice seals, each with a different focus. I'll begin our seal stories by briefly describing each species. Then, until the end of the cruise, I'll describe the different seal projects and how they work with these large marine mammals.

In just plain numbers, the crabeater seal is the most important seal in the Antarctic. It is partially because the estimates of its population have varied so widely (5- to 60-million) that the APIS program was conceived and developed. The crabeater, like all the Antarctic seals, is a "true seal," which means that it is well-suited to its aquatic environment but very awkward on land (or, in our case, on ice).

The California sea lions you may have seen at Sea World can get up on their hind flippers and waddle around pretty well, but they are a different type of seal, an "eared seal," so named for their tiny external ears.

The true seals move by pulling themselves around on their front flippers or, on the ice, by slithering like a giant inchworm. They can out-slither a running seal biologist, so they may be awkward but they are not helpless. In the water, they are creatures of speed, grace and beauty.

Crabeater seals grow to 7{ feet in length and reach a weight of about 500 pounds. They feed almost exclusively on krill, a tiny shrimplike creature.

Weddell seals are larger than crabeater seals, reaching lengths of almost 8 feet and weighing up to 750 pounds. They are the champion divers of the pack ice seals, sometimes reaching depths of 2,000 feet in their hunt for their preferred menu of fish and squid. Crabeater seals typically dive to less than 900 feet.

Weddell seals are special in other ways as well. They are able to keep breathing holes open in the ice during winter freezing conditions by chewing around the edges of the hole whenever they come up to breathe. This ability enables them to remain in the thick ice close to the continent where fish are most abundant, even in winter.

The rarest of the pack ice seals is the Ross seal. It is not as long as the crabeater and Weddell seals, typically between 6 and 7 feet, but weighs 350-500 pounds. Ross seals also prefer fish and squid. We have seen more Ross seals on our APIS cruise than most of our seal biologists have previously seen in their entire careers. As a result of our efforts on this cruise, the world will know more about Ross seal numbers, habits and health than ever before.

The Darth Vader of the seal world is the predatory leopard seal. Its diet consists of a menu of crabeater and Weddell seal pups, penguins, fish and krill.

Leopard seals are the largest of the pack ice seals, with lengths reaching more than 9 feet and weights greater than 650 pounds. They have a powerful head and neck, which they use to help subdue their prey in the water. Because they are predators, leopard seals also are fairly rare, but not in the same league as the Ross seal.

Wondering how a veterinarian gets close enough to a 500-pound seal to check its health? Stay tuned.

A group of biologists have just finished examining a crabeater seal. The tripod is used to weigh the seals, which are put in a sling and hoisted up. The light color of the seal indicates it hasn't been in the water in a while and its fur is dry.

This is the business end of a leopard seal. The seals are predators and feed on seal pups, fish, penguins and krill.

If this were a TV special, you'd have to turn your head now. This Adelie penguin is about to become lunch for a leopard seal.