Blue Whale – Animal of the Week

When we think of big animals, we often think of things that lived long ago. Turns out, the largest animal to have ever lived — either past or present — is with us today.

The blue whale, (Balaenoptera musculus) is the largest animal to have ever lived. It weighs in at an astonishingly heavy 100 tons, distributed over a length of 100 feet! That’s a weight of one ton per foot. They’re so big, there’s room for 50 people to stand on their tongue. Their heart is the size of a small car, like a VW bug. Baby blue whales drink 100 gallons of milk a day and can gain 200 pounds every 24 hours. Yes, that’s how big this animal is.

Bluish-gray above and paler below, their skin is mottled with white. Their flippers are 9 to 12 feet long, and their dorsal fin is greatly reduced.

Diet

Blue whales’ diet consists almost entirely of krill. They use baleen (long plates of stiff, modified hair) to filter huge volumes of water that they take in through their mouth. Their strategy is to find the highest concentrations of krill they can, so they typically feed from an average depth of around 100m. They stay below water for 10 to 20 mintues, with a longest dive time recorded of 36 minutes.

Population Size and Conservation

Found throughout the oceans of the world, blue whales populations were estimated to have been as large as one million individuals. Intense hunting however by the world’s industrialized nations reduced this to approximately 10,000 by the 1960s, when whaling was finally stopped. In less than 100 years, the population had been decimated to 1% of it’s former size, and the whales themselves had come perilously close to extinction.

Their current population seems to be holding steady, but it may not grow much because blue whales have slow birth rates. They reach sexual maturity from the age of 5 to 10 and can breed every 2 to 4 years. It is uncertain how long they live, though it’s probably well past the age of 50.

Sources

• Wikipedia – general information
• National Marine Mammal Laboratory of NOAA – general information