The Humpback Whales
by Wendy AronAveraging forty-five to fifty feet in length and thirty-three tons in weight, humpback whales are among the world’s largest and most remarkable creatures. Often referred to as “gentle giants,” humpbacks have roamed our seas for millions of years. Through most of this time, there were about one hundred to two hundred thousand humpbacks in the world. But in the 1700s, fishermen began to kill the humpback whale and other whales for money. They collected and sold whales’ oil, which was used to light lamps. Also valuable were the whales’ bony parts, which could be made into combs and other hard objects. Before long whales were used in a large number of products. More whales were killed to satisfy the increasing demand, and the world humpback population started to decline.
The situation got even worse in the 1800s, when the steam engine made faster boats possible. This, in turn, made the humpback whale easier to hunt. The explosive harpoon made it possible to kill more whales than ever before. By the mid 1900s just a few thousand endangered humpback whales were left in the world. One of the earth’s most extraordinary creatures was on the verge of extinction. In the 1960s, international laws were written to protect endangered humpback whales. Commercial whaling did not stop right away, but it did taper off over the next to decades. By the late 1980s, these creatures were no longer hunted commercially. With the whaling threat gone, the humpback population began to increase, and has been growing ever since. Now, there are three areas of the world where these creatures live. One population lives in the North Atlantic Ocean, one lives in the North Pacific Ocean, and one ranges from the Antarctic seas to the South Pacific Ocean.
Although they live in the water, humpbacks are not fish. They are mammals. Female humpbacks give birth to their offspring as most mammals do. They produce milk inside their bodies to feed their babies. In addition, these creatures are warm-blooded, which means that their bodies are at a constant temperature of about 97 degrees Fahrenheit. Because these whales spend a lot of time in chilly polar waters, they have developed special ways of keeping their bodies warm. Each whale has a six-inch thick layer of blubber just underneath its tough skin. The blubber traps the humpback’s body heat. These whales share another important trait with land-based mammals. They both must breathe air to survive. The humpback breathes through two large nostril-like holes on the top of its head. Together, these nostrils are known as the blowhole. The humpback may stay at or near the surface of the ocean for a long time. During this period, the whale breathes through the blowhole once every two to three minutes. But when the whale is getting ready to dive, it takes five or six deep breaths in a row. It is building up its oxygen supply so that it will be comfortable underwater.
Humpbacks can also be identified by other characteristics. Its best known feature is probably its gigantic pectoral (side) fins. Each of these fins can be one-third the length of the entire whale. The humpback can also be recognized by its large, flattened head, which accounts for one-third of the animal’s length. The head is dotted with bumpy knobs called tubercles. Individual whales have their own special markings as well. Each has a pattern of black and white markings on the underside of its broad tail fin, which is called a fluke. Scientists studying these creatures know that no two fluke patterns are the same. This helps them track individual whales.
Humpback Whale’s Role in the Food Chain
Despite their enormous size, humpback whales eat some of the ocean’s tiniest creatures. They survive on a diet of krill (small shrimp-like creatures), plankton, and small fish. The whale needs plenty of “fuel” to power its gigantic body and can consume up to three thousand pounds of krill and fish in a single day. The humpback does not simply swim along with its mouth open, waiting for food to be washed inside. These whales hunt and use amazing tricks to round up their prey. The whale’s best known hunting method is called bubble netting. Starting about fifty to one hundred feet below the water’s surface, a humpback swims around a school of fish in a slow upward spiral. As it swims, the mammal releases a steady stream of bubbles from its blowhole. The rising bubbles create a shimmering, moving curtain that confuses the fish and makes them squeeze into a tight ball. When the fish are packed close together, the humpback opens its huge mouth and lunges upward through the school. This method allows the whale to catch thousands of fish in one big gulp. Another common hunting technique is called the bubble cloud. In this method, the humpback blows air from its mouth to create a large cloud of bubbles. The bubble cloud confuses the whale’s prey and probably also hides the approaching whale. By the time the humpback appears, it is too late for the prey to escape.
The humpback whale is truly impressive. Although it is still considered endangered, these animals appear to be making a comeback. Will it continue? That largely depends on how healthy man keeps the oceans.
