Why are blue whales so enormous? - Asha de Vos
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Blue whales are the largest animals ever known to have lived on Earth. These magnificent marine mammals rule the oceans at up to 100 feet (30 meters) long and upwards of 200 tons (181 metric tons). Their tongues alone can weigh as much as an elephant. Their hearts, as much as an automobile.
We don't know much about how they communicate, but we think that blue whales make two primary kinds of calls. See some live footage, and hear some blue wall calls here.
The International Whaling Commission (IWC) banned all hunting of blue whales in 1966 and gave them worldwide protection. Recovery has been extremely slow, and only in the last few years have there been signs that their numbers may be increasing. Presently, there are an estimated 5-10,000 blue whales in the Southern Hemisphere, and only around 3-4,000 in the Northern Hemisphere. Learn more here.
The history of the American whaling industry from its 17th-century origins in drift and shore whaling off the coast of New England and Cape Cod, through the golden age of deep ocean whaling, and on to its demise in the decades following the American Civil War. Watch the PBS documentary about whaling here.
Krill are near the bottom of the food chain because they feed on phytoplankton. In the Southern Ocean, one species, the Antarctic krill, makes up an estimated biomass of over 500,000,000 tonnes, roughly twice that of humans. Of this, over half is eaten by whales, seals, penguins, squid and fish each year, and is replaced by growth and reproduction. Most krill species display large daily vertical migrations, thus providing food for predators near the surface at night and in deeper waters during the day.
See a video of a baby whale showing its baleen. Baleen is a filter-feeder system inside the mouths of baleen whales. The baleen system works when a whale opens its mouth underwater and then water pours into the whale's mouth. The whale then pushes the water out, and animals such as krill are filtered by the baleen and remain as food source for the whale.
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