Two weeks ago, Ferrebeekeeper presented a post about the smallest known mammal, the Etruscan shrew. Today we head to the opposite extreme: the blue whale (Balaenoptera musculus) is not merely the largest known living mammal, it is the largest animal of any sort known to have ever existed. The greatest dinosaurs, the colossal squid, and the most immense pliosaurs were pipsqueaks compared to the blue whale. The giant cetacean has been measured at lengths of 30 metres (98 ft). A single whale can weigh up to 180,000 kilograms (200 tons) which is about the weight of forty African elephants (or approximately one hundred million Etruscan shrews). Superlatives stop making sense when describing the blue whale: a human could swim through its largest veins; a whale can eat 4 tons of krill a day; it can make a noise louder than a jet engine. When I worked for the Smithsonian Institution back in the nineties, it was said that the longest object in the collection was the life-size blue whale model. It wasn’t until the Air & Space museum acquired a space shuttle that the Washington museums got something bigger (although maybe that’s because they decided not to assemble their Saturn V). If you want a true sense of the size of Balaenoptera musculus, here is a life size poster of one on the internet (be forewarned: unless your monitor is the size of a drive-in theater, you are just going to be scrolling hopelessly around an endless wall of blue-gray).
Although there are different groups which have slightly different physical characteristics, blue whales can be found in all of the deep oceans of the world (with the exceptions of Europe’s seas, the great gulfs of the Middle East, and the Arctic Ocean). I would like to tell you more about the lifespan, breeding habits, vocalizations, and social life of the blue whale, but, incredibly, very little is known about these aspects of the creatures. Scientists speculate that blue whales live to be about 80 years old (or possibly older), but they don’t know for sure. How whales choose mates is unknown (although it presumably involves the remarkable range of noises which they make). Gestation lasts anywhere from 10 to 12 months.
Once baby blue whales are born they grow fast! Blue whale calves can put on 4 kilograms (9 pounds) an hour. Adults are masters of the deep: fully grown blue whales can dive for up to half an hour to depths of 500 meters 1,640 feet. They have two blow holes behind a streamlined spray guard. Like the other mysticeti, blue whales are filter feeders. They take huge amounts of water and krill into their mouths and then push the water out through long baleen plates. When adults fully open their mouths the area is equivalent to the volume of a boxcar!
Blue whales are capable of traveling 50 kilometres per hour (31 mph) over short bursts, so back in the days of sail, a blue whale encountering a ship would simply swim away. Only when humankind began to make modern ships powered by fossil fuels could we keep up with the gentle giants. Alas for the whales–we learned to build such ships (and explosively propelled harpoons) and soon we were killing the creatures by the hundreds of thousands so that they could be rendered into oil. Between the 1880s (when the whales first began to be hunted en masse) and the 1920s the whales’ population declined from 350,000 to perhaps a thousand. All nations stopped hunting the whales in the early 1970s. In less than a hundred years, humans almost eradicated the largest animal ever known…yet, in the end we have not yet wiped out the blue whales. They are still here. As you read this, there is a creature the size of a space shuttle eating millions of krill somewhere in the vasty oceans.