Sunday, January 24, 2010

Orca Sighting

As we come into late summer here in Antarctica, the sea ice covering the Ross Sea has melted back almost as far as McMurdo. That means that our helicopter rides back to McMurdo from the dry valleys start to scoot along the edge of open ocean, rather than traveling over solid ice. This makes for great sight-seeing, because there's so much life in the open ocean, even all the way down here! On the ice edge, we see penguins (both Emperor and Adelie), seals, and a lot of whales.

When we flew back from F6 on Saturday, we saw a lot of orcas. My camera doesn't do a great job from a distance, but in this video you can see a lot of them surfacing:

Orcas live just about everywhere in the world, but they tend to prefer polar waters, such as the Ross Sea of Antarctica where I am. They tend to stick to coastal areas, because that's where their food lives. While orcas are commonly called "killer whales", not all of them behave like killers. There are several types of orcas that we could see down here: Type A, B, and C. Type C are the smaller orcas that you see in the video. They have a duller white saddle (that white patch behind their dorsal fin) and eat fish. That's why they're along the ice edge here. The ice has just melted and broken away, so there's a lot of fish now without protection!

Type B are bigger and eat larger animals like seals (and penguins, if they were able to catch them, but penguins are usually too fast). In fact, when I met Sir David Attenborough last weekend, he narrated for us footage the BBC had recently shot of several orcas creating a wave to knock a seal off of a floating ice chunk and into the water so they could eat it!

Type A are the biggest and eat even larger animals, like minke whales. We also have a lot of minke whales in our waters here. In fact, we can see them from outside our lab window in the channel cut by the icebreaker! Minke whales are smaller, baleen whales. Baleen whales are a type of whale that have a plate for filtering small plankton from the water (rather than teeth for eating animals). So, minkes are related to humpback whales and Right whales, which are also baleen whales. It's easy to tell the difference between an orca and a minke because of the size, but also the shape of the dorsal fin. A minke's dorsal fin is small and curved. It looks kinda like the satellite radio antennas that you see on cars. (See what I mean using the photo on Wikipedia.)

We are hopefully going to the field tomorrow to visit Cape Crozier, the final penguin rookery I'd like to sample. Keep your fingers crossed that the weather cooperates!