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Blue Whale (Balaenoptera musculus)

Blue Whale (Balaenoptera musculus)

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).

blue-whale-space-shuttle

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.

Blue Whale Mother and Calf from Amos Photography

Blue Whale Mother and Calf from Amos Photography

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

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.

A diver with an immature blue whale

A diver with an immature blue whale

Baird's Tapir (Tapirus bairdii)

The Perissodactyls (horses, rhinos, and tapirs) were the planet’s dominant grazers for many millions of years–from the beginning of the Eocene to the end of the Miocene–but, in the most recent geological period they have been greatly outnumbered and outcompeted by the multitudinous artiodactyls (pigs, cows, deer, goats, antelopes, giraffes, and so on). The vast distance separating the Earth’s remaining tapirs illustrates how much their range has shrunk. Three species live in very different parts of South America and one live on the other side of the world in Malaysia and Indonesia.  The tapir species look different as adults but their incredible similarity as calves indicated their fundamental closeness. Such a study is also a study of insufferable cuteness since juvenile tapirs, with their waving proboscises and dappled coats are very endearing.  Although the tapirs are vanishing from the wild there are more of each of the 4 species in zoos every year.  Here are some more of the new ones for your viewing pleasure!

Brazilian Tapir, also called Lowland Tapir (Tapirus terrestris)

Malayan Tapir (Tapirus indicus)

Mountain Tapir (Tapirus pinchaque)

Hooray for little tapirs!

A Dugong and Diver (photograph by Duane Yates)

There are about 120 living species of marine mammals (although that total may tragically become much smaller in the very near future).  Of this number, only one species is herbivorous.  The mighty dugong (Dugong dugon) is the last animal of its kind, a gentle lumbering remnant of the giant herds of sirenian grazers which once graced the world’s oceans. Dugongs are distinct from the three extant species of manatees (the world’s other remaining sirenians) in that they never require fresh water at any point of their lives.  Additionally dugongs possess fluked tails in the manner of dolphins and whales.

Dugong Range

Dugongs live in shallow tropical waters of the Indian Ocean and the Pacific Ocean.  They range from Madagascar to the Philippines, but are only common along the north coast of Australia (where conservation efforts and a limited human population have allowed them to live in peace).  Dugongs can swim in deep oceans for a limited time, but prefer to stay on continental shelves where they can feed on seagrass and marine algae.  Their all-salad diet does not prevent them from growing to substantial size: some individuals have been known to reach more than 3.5 meters in length (11 feet) and weigh over 950 kilograms (nearly a ton).  Although Dugongs can live more than seventy years, they reproduce extremely slowly.  Females gestate for over a year and then suckle their calf for around 18 months. Calves may stay with their mothers for many years after being weaned and need almost contact with their mothers for security and affection until they are almost grown. Young dugongs swim with their short paddle-like flippers, but adults use their tail for propulsion and only steer with their flippers.

Dugong and Calf

Dugongs have a variety of vocalizations with which they communicate.  Usually they live in small family units.  Great herds are not unknown but  seagrasses do not grow in sufficient quantity to support such numbers together for long.

Like the other sirenians, Dugongs have dense bones with almost no marrow (a feature known as pachyostosis).  It has been speculated that such heavy skeletons help them stay suspended just beneath the water in the manner of ballast.  The lungs of dugongs are extremely elongated, as are their large elaborate kidneys (which must cope with only saltwater).  Additionally, the blood of dugongs clots extremely rapidly.

Dugongs face a number of natural threats, particularly storms, parasites, and illnesses.  Because of their large size they are only preyed upon by alpha predators such as large sharks, killer whales, and salt-water crocodiles.  As with other marine animals, the greatest dangers facing dugongs come from humankind.  For millennia Dugongs have been hunted for meat, oil, and ivory. Traditional medicine from various portions of their range (wrongly) imputes magical properties to parts of their bodies. Worst of all, dugongs are frequent victims of boat collisions or are killed as by-catch by fishermen trying to catch something else.

Close-up of a Dugong (Julien Willem)

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