Using her gadgets, she can record a whole world at once. She shows me a printout from an earlier Sea of Cortez cruise with Gilly, when sperm whales surrounded them. “We knew they were down there beneath us,” she says, “but you can’t tell what they’re doing from the boat.”
The acoustic reading shows a ten-minute window, with time on the horizontal axis and depth on the vertical. One thick band stretches from 700 feet or so to more than 900 feet. This is the deep scattering layer, the zooplankton and lanternfish. Individual squid, one visible as a blue-green smear, the other in orange, are among them, perhaps feeding. A school of squid shows up a few minutes later, loitering about 60 feet from the surface. The real drama, though, starts at one minute and 55 seconds, with a pair of red and orange squiggles: two sperm whales, one near the surface and the other more than 300 feet under the boat. The latter dives to a school of squid nearly 400 feet deep. The tracks of the squid and the whale converge, are lost as they move into the band of fish, and pop out of the jumble.
Seeing this, I think back to a night near the cruise’s end, when I was alone on the bow of the BIP XII. The trawler was chugging over a still sea, and the night was hypnotically quiet. Then, somewhere in the distance, I heard the spouting of whales. But I could see nothing, and the boat continued on in languorous pursuit of the moon’s reflection.
For a long time, we didn’t know much more than that about the whales. But now we have a better idea of what is happening in that strange world where the sperm whale swims. We can imagine the wan glow from a school of lanternfish, the jumbo squid among them, and a sperm whale moving through the gloom with relentless purpose. The whale searches with usual clicks and gives a quick creeeeeek! as it locks onto the squid. There is a rush of pressure from its head wave as it surges to its prey, jaw agape, and the jet from the squid as, panicked, it bursts away into the darkness.
Eric Wagner, who wrote for Smithsonian about cranes in Korea’s Demilitarized Zone, frequently reports for Smithsonian.com.