ScienceNow has a short but intriguing piece by Elizabeth Pennisi called “A whale’s virtual reality.” It summarizes results presented by Jeremy Goldbagen and his colleagues on some baleen whales that feed on “bait balls”: groups of fish or krill (shrimplike marine crustaceans). The whales lunge toward the balls, opening their mouths and ingesting huge amounts of water along with the prey. Then they expel the water through their baleen plates (extensions of the mouth’s mucus membranes).
Whales were tagged with radio transmitters affixed to the beasts with suction cups. Pennisi reports the pretty amazing findings:
The work showed that in one giant gulp, a blue whale—the biggest creature on Earth—takes in 125% of its body weight in water and krill. During their dives, the cetaceans ram into patches of krill, opening their mouths wide and wrapping their jaws around prey-laden water, a move that stops them short. Next, they close their mouths and push water through their baleen, a system of plates that filter out the food, then speed up for another feeding bout.
But details about this feeding strategy had been lacking. This past summer, Goldbogen monitored several blue and fin whales with new tag technology that detects the changes in the whales’ orientation in space, much like smart phones “know” whether they’re held in a horizontal or vertical position and adapt screens accordingly. For the 6 to 24 hours they are attached to the whale, the tags also record depth and sound; from the loudness of the water rushing past a diving whale, researchers can calculate its speed. “We use these sensors to reconstruct what the whales are doing,” Goldbogen said.
The new tags show that as they gulp, the whales often twirl around like a corkscrew with surprising agility, Goldbogen reported at the meeting. They also will lunge from all different angles, not just horizontally, as previously thought. “We see these amazing maneuvers,” Goldbogen said.
125% of its weight in water and prey!!
Here’s a computer animation based on the tracking data from a single blue whale:
In the video [above], a tagged blue whale dives twice over the course of 19 minutes. The movie shows the whale moving at about 50 times its cruising speed. The first dive, to about 15 meters, takes about 2.5 minutes in real life; the second one, which includes feeding bouts, lasts more than 12 minutes and reaches down to 180 meters, where the whale lunges five times in quick succession, as if it were on a roller coaster.
This is not a great video, but it’s the best I’ve found on YouTube to show the feeding behavior. In the first ten seconds, you see the whale twist its body and open that huge mouth to ingest a group of krill. It’s pretty amazing that the largest animal on earth sustains itself with tiny invertebrates.