Mark Eveslage, age 11, of Burlingame, California, for his question:
Which is the biggest animal in the world?
This is a sad story, for the world's largest animal may soon become extinct. The tragedy is even sadder because he is such a gentle giant. In his whole life, he never hurt any creature larger than a shrimp. He did nothing to foul up his environment. He did nothing at all to harm mankind. Yet man the hunter is responsible for bringing the largest of all nature's children to the brink of extinction.
Imagine a new born infant that weighs four tons and measures 24 feet long. He is a baby blue whale, born at the surface of some tropical ocean. For the next 14 years or so, he will patrol the seas from pole to pole filling his tummy on floating plankton and growing. If he survives this long, he will be 100 feet long, measure 45 feet around his bulging waistline and weigh about 120 tons. He has reached his full size and with a lot of luck he can expect to live to celebrate his 50th birthday.
The adult blue whale is the largest animal in the world and also the largest animal that ever lived upon the planet Earth. In the remote past, his ancestors left the ancient seas and adapted to life on the land. Then the global climate became a global drought that lasted ten million years or more. Many of the land animals deserted the parched, arid continents for life in shallow waters by the seas.
Among them were the ancestors of the whales, who ventured into deeper waters. Eventually their descendants adapted to life in the ocean. Limbs became flippers and flukes and their swimming improved. They gulped great gobs of air to last through long plunges below. They added masses of blubbery fat to keep out the cold while they chased their food into polar seas. Eventually the whales became so enormous that they needed deep water to support their bulky bodies.
The largest species became the blue whale, named for the slate¬blue color of his gleaming back. Usually his paler underside is coated with tiny yellow diatoms, which is why some people call him the sulphur bottom whale. The giant of giants is a baleen whale, a name that refers to his unusual dental arrangement.
Instead of teeth he has long narrow strips of baleen, somewhat like tough pliable plastic. Hundreds of baleen strips hang in a curtain from the roof of his cavernous mouth. His food is plankton, which he gulps with great mouthfuls of sea water. His tongue, which weighs two and a half tons, is used to push the water back out through the baleen screen. This sifts out the tiny morsels of food for swallowing. His tummy holds a ton of plankton food and he expects to fill it every day
The giant of giants has 50 tons of muscles and 25 tons of fat, plus a 20 ton skeleton to support his massive bulk. His heart weighs 800 pounds and his liver weighs half a ton. He travels near the surface, often as fast as 14 miles per hour. Usually he dives about 500 feet and stays below five or ten minutes. When he comes up for air, he spends almost an hour emptying and refilling his roomy lungs.