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Posts Tagged ‘whale’

A Whale-sized Hole in the Ocean Ecosystem

Thursday, December 2nd, 2021
Humpback whale mother and calf Credit: © Shutterstock

Humpback whale mother and calf
Credit: © Shutterstock

A study published in November 2021 reported more accurate measurements of just how much giant whales eat—and just how much they defecate (eliminate solid wastes)—which has surprising effects on the ocean ecosystem and even global climate. The research demonstrates that ocean food webs are more complex and intertwined in surprising ways, more surprising than simple predator-prey relationships.

Baleen whales, including the blue whale, bowhead whale, fin whale, and right whale, are among the largest animals that ever lived. These gigantic beasts feed mainly on millions of tiny shrimp-like krill and other zooplankton that they filter out from huge gulps of seawater. Calculating exactly how much they eat has always been a difficult exercise.

A gray whale filters food from water by squeezing the water out of its mouth through thin plates called baleen. Credit: © Shutterstock

A gray whale filters food from water by squeezing the water out of its mouth through thin plates called baleen.
Credit: © Shutterstock

In the latest study, scientists used Global Positioning System (GPS) tags to follow more than 300 baleen whales as they swam and ate their way through the oceans. This tracking enabled the scientists to record each time a whale lunged to gulp a mouthful of krill. Sonar and drones flown overhead were used to determine the dimensions of the krill swarm swallowed, providing the most accurate measure yet of how much each whale was consuming. The results were surprising. The baleen whales were routinely eating three times or more the amount of food previously estimated. Across all species studied, baleen whales consume an average of 5 to 30 percent of their body weight each day. A single average-weight adult blue whale can consume about 40 million krill a day, equaling about 4 tons (3.6 metric tons). Of course, what goes in must come out. So equally astonishing was the amount of feces (solid bodily waste) that baleen whales produce as measured by the study. A blue whale can excrete more than 50 gallons (190 liters) of waste in one go.

The populations of many kinds of whales collapsed in the 1900’s because of excessive whaling. Whalers killed so many blue, bowhead, humpback, and right whales that these species nearly became extinct. The researchers estimate that before the 1900’s, baleen whales in the Southern Ocean consumed 430 million tons (390 million metric tons) of krill annually. That’s twice as much krill than exists today. With so many krill-eating whales removed from the ecosystem, researchers expected krill populations to increase. But krill populations dropped after most of their predators were killed off—a fact known among ocean scientists as the krill paradox.

How could this have happened? Researchers know when whales feed on krill, a good amount of nutrients are excreted in their feces afterward. In the nutrient-poor Southern and Pacific oceans, this cycling of nutrients is especially important. The nutrients excreted are rapidly taken up by blooming populations of simple one-celled algae in the oceans called phytoplankton. The phytoplankton in turn serve as food for more krill, which are then food for whales. More whales mean more whale poop—fertilizer in the ocean—which means more krill.

When living things grow, they add carbon to their bodies, removing some carbon from the atmosphere. In another unexpected finding, the researchers estimate that restoring baleen whale populations to 1900 levels could foster plankton blooms that would remove 235 million tons (215 million metric tons) of carbon from the atmosphere, helping to combat global warming.

Tags: climate change, food webs, krill, ocean ecosystem, whale
Posted in Animals, Current Events | Comments Off

Tracking the Unicorns of the Sea

Thursday, November 3rd, 2011

Nov. 3, 2011

Seven high-tech narwhals are helping an international group of researchers in northern Canada learn more about the habits of this Arctic whale known for its unusual spiral tusk. In August, the researchers painlessly attached satellite radios with transmitters to nine narwhals (pronounced NAHR hwuhl). (Two of the transmitters apparently either malfunctioned or fell off.) About two-thirds of the world’s estimated 50,000 to 80,000 narwhals spend the summer north of Baffin Island, off the coast of the Canadian territory of Nunavut. This month, the radios are allowing the researchers to track the narwhals as they move south to avoid being trapped by winter sea ice.

A male narwhal has a long, spiral tusk growing forward from its upper jaw. World Book illustration by Colin Newman, Linden Artists Ltd.

The narwhal’s ivory tusk, which can grow to 10 feet (3 meters) long, is actually its left tooth. Males have at least one tusk, though some develop two. In females, the teeth grow only about 1 foot (0.3 meter) long, the length of most males’ right tooth. Most scientists think the tusk plays a role in selecting mates. Research also indicates that the tusk is a sensory organ. It may detect water temperature, pressure, and other sensations. Tiny tubes connect millions of nerve endings inside the tusk to the water outside.

The transmitters on the narwhals beam location information to an artificial satellite when the narwhal comes to the surface to breathe. The signals also relay how far below the surface the narwhal dived and how long it stayed underwater. The researchers hope this information will help them learn how narwhals are adjusting to a loss of sea ice in the Arctic linked to global warming. The research team, which is being funded by the conservation organization WWF-Canada, includes members of the Inuit community in Nunavut. The Inuit have traditionally hunted the narwhal.

Additional World Book articles:

  • Oceanography
  • Unicorn

Tags: climate change, global warming, inuit, narwhal, nunavut, whale
Posted in Current Events, Environment, Science, Technology | Comments Off

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