Blue Whale
The blue whale is the largest living animal and the largest animal, by weight, ever known to have existed. These gentle giants are currently endangered.
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea
Family: Balaenopteridae
Genus: Balaenoptera
Species: B. musculus
Common Names: Blue Whale, Sibbald’s Rorqual, Sulphur Bottom
Blue whales usually travel singly or in pairs, though they may sometimes gather in large groups at times. Blue whales migrate between their feeding grounds in cold water to their breeding grounds in warmer waters, a distance which may be as much as 4,000 miles.
Blue whales can dive to depths of over 1,000 feet, and can stay underwater for over 15 minutes without taking a breath. They eat tiny shrimp-like creatures called krill, which they filter through their baleen after drawing immense amounts of water into their mouths.
Like other whales, blue whales breathe through nostrils on top of their heads, called blowholes. The blue whale has two such nostrils, and can spout its breath up to 30 feet high.
Blue whale pregnancy lasts up to a year, and when calves are born they are already over 20 feet long, and weigh several thousand pounds. To feed her newborn, a mother blue whale will product up to 700 pounds of milk in a single day.
Blue whales are named for their coloration, which is a grayish-blue that appears mostly blue when the animal is in water. They are long and slender, with a small dorsal fin and two elongated pectoral fins.
The blue whale’s mouth is full of baleen, bristle-like structures that serve to filter tiny organisms out of the water it draws into its mouth.
Blue whales are the largest living animal, and the largest known animal to have ever lived. Blue whales can grow over 100 feet long, and weight nearly 200 tons (400,000 pounds).
The blue whale is a “rorqual”, a member of the family of whales that includes the minke whale, sei whale, gray whale, and humpback whale.
The only animals, other than humans, known to pose a threat to blues are orcas. The blue whale’s massive size scares off most predators, and it can deliver a powerful slap with its giant tail.
Blue whales were hunted by human whalers beginning in the 1930s, when new harpoon developments made them a more viable target. Since 1966, hunting blue whales has been banned worldwide, though certain countries continued to hunt them illegally into the 1970s.
Blue whales are mentioned in Herman Melville’s famous novel Moby Dick, where they are called “sulphur bottoms”. This name refers to algae called diatoms which are known to accumulate on blue whales’ undersides, giving them a yellowish hue.
Though they were once abundant, blue whale numbers decreased significantly due to human hunting. In 1926, there were around 150,000 blue whales, and as of 2018 that number is believed to be between 10,000 and 25,000.
Even after the international ban on whaling, blue whales continue to face threats due to human activity. Shipping vessels cause problems for blue whales, due to the danger of collision with whales, and contributing to underwater noise which can alter their behavior.
References
https://en.wikipedia.org/wiki/Blue_whale
https://www.nwf.org/Educational-Resources/Wildlife-Guide/Mammals/Blue-Whale
Shirahai, Hadoran & Jarrett, Brett (2006). Whales, Dolphins & Other Marine Mammals of the World. Princeton, New Jersey: Princeton University Press.
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