In impact, the large mammals have two completely different feeding modes: conserving power when prey is scarce and utilizing up extra oxygen to dive deep and soak up massive quantities of prey when krill are ample.
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A blue whale surfaces to breathe in an undated picture from the U.S. National Oceanic and Atmospheric Administration (NOAA). And krill also dictates when the large animals feed, a new study suggests.
Blue whales can consume up to 4 tons of the tiny shrimp-like creatures in a single day.
Understanding blue whale feeding behavior will help inform protections for the endangered species and its recovery needs, the scientists say.
As much as 2 million krill can swarm collectively, however not all krill patches are equally dense – and the whales are paying consideration. That’s very much applicable to blue whales – the largest animals to live on Earth – and a new study has shed light on the efficient foraging strategies that they employ to optimize the energy gain from each of their krill hunts.
The feeding pattern that focuses more effort on the densest krill patches provides a new example of blue whale foraging specializations that support the animals’ tremendous size.
NOAA ecologist Elliot Hazen said that scientists have always wondered how blue whales manage to eat efficiently for supporting their enormous body.
“Lunge-feeding is a unique form of “ram-feeding” that involves acceleration to high speed and the engulfment of large volumes of prey-laden water, which they filter”, Goldbogen noted. “Now we all know that optimizing their feeding habits is one other specialization that makes the a lot of the meals accessible”.
The research team compared the feeding strategy of 14 tagged blue whales to 41 earlier tagged blue whales near the California’s coast, collating their gathered date with acoustic surveys that gauged the density of the krill they attack.
Unlike what many myths tell, blue whales can not swallow a whole boat and crew because of the dense baleen plates in their mouths that allow only tiny prey to enter.
“Blue whales do not live in a world of excess and the decisions these animals make are critical to their survival”, said principal investigator Ari Friedlaender from Oregon State University. He added, “If you stick your hand into a full bag of pretzels, you’re likely to grab more than if you put your hand into a bag that only had a few pretzels”.
We found that blue whales have a complex strategy of switching from conserving oxygen when prey quality is low, to intense foraging at the expense of oxygen when prey quality is high.
The blue whales tend to feed more intensely when the krill are high in numbers, but refrain from feeding when there are less krill.
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According to the IUCN Red List, there are only between 10,000 and 25,000 blue whales living in the world’s oceans, which is about 5 percent of the total number of blue whales in existence prior to the grim effects of the whaling industry on their population.
