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September 27, 2013

A Blue Whale’s Life Story Revealed Through Ear Wax

Instead of our weekly Creature Feature, we’d like share an awesome new finding about one well-known ocean creature, the blue whale. Scientists discovered that earwax can reveal amazingly details about the life of whales, according to a study published last week in the scientific journal Proceedings of the National Academy of Sciences.

Blue whales, and other species of large baleen whales, build up a long cone of layered wax within their ear canal. Called an earplug, this amber-colored cone can reveal amazing information about the life of a whale.

Eaxwax is actually made up of wax, keratin (like your hair and fingernails), and other molecules called lipids. Lipids can store compounds like pesticides, mercury, and hormones, allowing researchers to track these compounds over the course of a whale’s life.

In 2007, a group of U.S. scientists took an earplug from a male blue whale after it was killed by a ship near Santa Barbara, California. They already knew that an earplug is layered, just like tree rings, with alternating dark and light bands of wax. The darker layers are deposited when a whale is feeding, and lighter layers during period of migration. After sawing the earplug in half, the scientists used these layers to calculate that this blue whale was about 12 years old when he died.

The earplug also revealed that this whale was exposed to a number of long-lasting environmental pollutants, like the insecticide DDT. By analyzing the chemicals in each waxy layer, the researchers were able to map the concentrations of chemicals in the whale’s body throughout its life. Chemicals like DDT stay in the environment for decades, long after being banned, passed on from parents to offspring or through the food chain. This blue whale inherited about 20 percent of the long-lived chemicals in his body from his mother, during her pregnancy and from her milk.

The scientists also detected mercury in the earplug, including two “pulses” of higher-than-usual levels. This whale lived off of the California coast, so the researchers suspect that a local increase in mercury caused the two dramatic increases.

Who knew that simple earwax could provide so much information about a whale? Now that we know how useful they can be, the scientists hope that other researchers will utilize earplugs as part of their research.

Earplugs aren’t the only cool thing about blue whales:

  • Blue whales eat krill, tiny ocean creatures that they filter from the water with their baleen. Blue whales can collect more than 6,600 pounds of food a day.
  • Blue whales are probably the largest animal that has ever lived. The largest individuals can weigh up to 190,000 kilograms, or 30-40 African elephants!
  • This bulk doesn’t slow them down—blue whales are also some of the world’s fastest swimmers. They can reach speeds of almost 30 miles per hour if they’re chased.
  • A blue whale’s heart is the size of a small car.
  • Blue whales can live as long as humans—about 80 to 90 years.
  • A blue whale’s call, at about 180 decibels, is louder than the sound of a jet aircraft taking off. Those calls can travel through the water for thousands of miles, at frequencies below the range of human hearing.
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