Listen to this Science Update to hear about how a male hummingbird makes sounds with his tail feathers to attract females.
Visitors to Antarctica have to bundle up in heavy-duty, government-issued parkas and other cold-weather gear. But in this Science Update, you'll hear about a daring group of underwater photographers that wear nothing but a layer of blubber.
Seals that spy on fish. I'm Bob Hirshon and this is Science Update.
Nature photographers routinely scale mountains and dive the ocean depths. But for the especially difficult job of shooting film under the Antarctic ice, scientists have recruited a team of specialists: Weddell seals.
Lee Fuiman of the University of Texas Marine Science Institute says over the course of 3 years, 15 different seals were equipped with cameras and a host of other sensors.
One of the great things we were able to do is to use the speed, compass bearing, and depth data together with a clock that's on-board to calculate the three-dimensional position of the animal for every second during a dive.
That way, the scientists could match the video with the seals precise location.
Fuiman says they learned a lot—not only about the seals' behavior but also about their prey. For example, the Antarctic silverfish, an important species in the food chain.
Having more information about the habits of that fish—especially underneath the frozen ice surface where it's virtually impossible to collect this fish through other methods—is very useful for understanding the ecological interactions of the sub-ice environment.
The results of the study appear this month in the journal marine biology. For the American Association for the Advancement of Science, I'm Bob Hirshon.
Making Sense of the Research
There are two main advantages to using seals to study the undersea life: First of all, they're great divers and they don't need wetsuits, oxygen tanks, or insurance policies. Secondly, by putting the cameras on the seals, you get to study the seals' behavior while they take pictures. So it's a two-for-one deal.
Believe it or not, scientists have been strapping video cameras to seals and other sea creatures for several years now. It helps the scientist experience parts of the animal's life that humans would ordinarily never glimpse. But this marks the first time that an animal cinematographer was used specifically to study another species. It's a natural fit to use the seals to study their prey, since a seal will follow a food fish even more closely than a tabloid photographer on Julia Roberts.
What did the scientists learn? Well, among other things, they discovered that Antarctic silverfish hang out in deeper waters during the day than at night: 300 feet deeper, in fact. And how deep they go depends on how strong the light is—even though the closest they usually get to the surface is about 800 feet below sea level. They also learned some new things about the Antarctic toothfish and the bald rockcod.
These discoveries may not sound very significant, but actually, Fuiman says it's crucial to understand how small prey species like this behave. Because if something's happening that might make them act differently, that could have a big effect on the seals and larger animals that feed on them. And eventually, the effects could ripple through the entire Antarctic ecosystem, and even beyond.
Incidentally, scientists in other fields are using surrogates to explore dangerous or hard-to-reach places. For example, scientists have used walking robots to explore the insides of volcanoes, which are far too dangerous for humans or animals to venture into.
Now try and answer these questions:
- Why use seals to photograph life under the Antarctic ice?
- What are some of the discoveries the seals made?
- Why are these discoveries useful?
- If the researchers used underwater robots instead of seals, what would the advantages and disadvantages be?
- Would animals answer some scientific questions better than robots, and vice versa? Give examples.
Team Fuiman Research page has more information and links to other research on fish.
National Geographic's Crittercam is a similar project that involves such creatures as sharks and sea turtles.
Origins: Antarctica has a gallery of images and dispatches from a 2001 expedition to Antarctica.