The blue whale is the biggest animal in world history — not just currently the biggest animal, but the biggest to have ever lived — and for many years, that has been a mystery to scientists.
Now, scientists think they have an understanding of why that is.
The blue whale can grow to nearly 100 feet long and 200 short tons, which makes it bigger than even the biggest dinosaur that ever lived: Argentinosaurus, which grew to be 130 feet long and 100 tons. But scientists have struggled to understand how the blue whale is able to maintain this incredible size while subsisting entirely on a diet of krill, which are tiny shrimp-like creatures. A new study may have cracked the code however: blue whales are very clever and have very efficient ways of eating, according to a Christian Science Monitor report.
Blue whales will eat four tons of krill every single day, opening up their huge mouths and swallowing large groups of them along with lots of sea water, which is then filtered out of their mouths with baleen that keeps the krill in, allowing them to gulp it down. So it would seem that blue whales are rather boring in that regard: they find krill, gulp it up, and repeat as necessary. Or, at least that’s what scientists thought, until this new study found that they have some very sophisticated methods for eating.
The findings, published in Science Magazine, indicate that scientists have always suspected there was more to the story than that, said Elliott Haze of the National Oceanic and Atmospheric Administration (NOAA) in a press release. And as it turns out, that suspicion was right: whales have optimized feeding behavior to avoid wasting effort and energy that is extremely precious for survival.
One of these methods has been known about before, and it’s called “bubble netting,” where the whales will dive below the krill and send up bubbles to displace them, making it easier to grab the krill, but digital acoustic recording tags on 55 blue whales off the coast of California have provided evidence of another interesting method they use.
Not all krill groups are created equal: some are denser than others, so a whale may get more krill with a gulp depending on this factor. Scientists have discovered that blue whales can recognize how dense these krill patches are, and will adjust their behavior accordingly. If a krill patch is dense, the blue whale will be happy to exert plenty of effort gulping as much as possible. But if the krill patch isn’t dense, the blue whale expends less energy, taking fewer lunges and saving its oxygen.
Scientists think there’s a chance migration patterns play into this, although migration isn’t the same for all blue whales. Some move around seasonally, while others hang around the Southern California region year-round.
Blue whales are classified as endangered, with about 10,000 to 25,000 individuals in existence. There used to be hundreds of thousands, but modern whaling has caused their numbers to plummet, and the total population is about 5 percent of the total before the whaling industry came into existence. Populations are only just now recovering from this devastating reality.
Blue whales are magnificent creatures, long and slender with a bluish-grey color to them and a lightish underside. There are three distinct subspecies, one in the North Atlantic and Pacific, another in the Southern Ocean, and another in the Indian and South Pacific Oceans that is often called the pygmy blue whale.
Blue whales flourished prior to the arrival of human hunters at the beginning of the 20th century. Due to their tremendous size, they don’t have to fear much in terms of predators. However, whaling reduced their numbers so much that the international community stepped in in the 1960s to protect them. The species remains endangered although the populations are starting to recover. Scientists believe that at one point, there were about 239,000 blue whales, vastly more than there are today.
Blue whales begin mating in autumn, and that continues through the entirety of winter. Their actual mating habits and breeding grounds remains largely a mystery to scientists.
Females usually give birth once every two or three years at the beginning of winter, with a gestation period of 10 to 12 months. The calf will typically weigh about three tons and will be about 23 feet in length. They guzzle between 100 and 150 gallons of milk from their mother each day, and double in size after six months when the calf is fully weaned. Whales reach sexual maturity at around five to 10 years of age, and they live to be about 80 years old — although scientists aren’t quite sure as there aren’t good records back to whaling times. The longest scientists have ever tracked a whale is 34 years.
Blue whales have a natural enemy in the orca, which often attack blue whales, with an estimated 25 percent of blue whales showing scarring from killer whale attacks.