Rorquals (ROAR-kwulz) are large baleen (buh-LEEN or BAYleen) whales. Like all baleen whales, they are filter feeders. These whales do not have teeth. Instead, they have many overlapping plates called baleen plates that hang like a curtain from the upper jaw. These plates are made of a material called keratin (KARE-ah-tin). This horny, fingernail-like material frays out into thin hairs at the end of each strand to make a strainer. Rorquals also have a set of ridges and groves along the bottom of their mouth and throat. When they open their mouth to feed, the grooves expand and make the inside of their mouth very large so that they can suck up a lot of water. They then push the water out through the baleen plates and use their tongue to lick up food that remains.
Rorqual whales can be anywhere between 32 to 102 feet (10 to 31 meters) long and weigh as much as 200 tons (181 metric tons). Some rorquals have a dorsal fin on their backs, and others have particular bumps or ridges on their head and back that help to distinguish them from other rorquals. Females are usually larger than males.
Rorquals are found in all of the oceans of the world and the seas that connect to these oceans. They do not live in the parts of the Arctic and Antarctic Ocean that are covered by ice, since they must come to the surface to breathe. Rorquals are more often found in shallower parts of the ocean that are closer to land. These areas are called continental shelves.
Rorquals can be seen most often in open waters over continental shelves. They can sometimes be found in bays and inlets near land.
Rorqual whales eat small fish, squid, and other small marine animals. Much of their diet is made up by krill, which are tiny shrimp-like animals. They obtain their food by filtering large quantities of water through their baleen. Normally they feed at depths no greater than 300 feet (91 meters) and stay under water no longer than ten minutes.
To capture the large amount of food that they need, rorquals expand their mouth and open it wide. Then they close their mouth most of the way, leaving only the baleen exposed, like a sieve (siv) between their lips, and squeeze the water out by ramming their tongue against the baleen. This pushes out the water and leaves the food behind. The blue whale, the largest rorqual, can eat 8 tons (7.3 metric tons) of krill per day.
BEHAVIOR AND REPRODUCTION
Rorquals normally swim at around 10 to 20 miles per hour (16 to 32 kilometers per hour). Some species, such as the fin whale can swim at speeds of 23 miles per hour (37 kilometers per hour) for short periods. Groups, or pods, are usually made up of two to five individuals, but sometimes large groups of rorquals come together where food is abundant. Generally rorquals do not dive deeper than 300 feet (91 meters) below the surface.
Even though different rorqual species live in different parts of the world, they all follow a migration pattern. This means that they spend part of the year in a warmer area and then move, often over great distances, to a cooler area for the other part of the year. Rorquals time their reproduction with this yearly cycle by giving birth in the warmer area and feeding in the cooler area. A female rorqual is pregnant for about a year, depending on the species, before she gives birth to a single calf.
When the calf is born, it measures between 9 and 23 feet (2.7 and 7 meters) long. The young nurse, feed on their mother’s milk, for about a year and grow rapidly. They become mature between five and fifteen years and live, on average, fifty to eighty years.
RORQUALS AND PEOPLE
All species of rorquals have been hunted by people for their oil and meat. Their oil was used in making margarine, soap, and lubricants, or industrial oils, until the 1980s. During the early 1900s humpback whales were hunted heavily, because they live close to land and their population was severely reduced. Hunters then began hunting of a number of other rorqual species. The blue whale became a preferred target of whalers, whale hunters, because of its size and the quantity of oil, meat, and blubber that it could provide. Larger blue whales could contain as much as 9,000 gallons (34,000 liters) of oil. Through efforts of the International Whaling Commission, environmental groups and other agencies, large scale commercial whaling ended by 1990. Today, whale watching is more popular and profitable than hunting. According to the World Wildlife Fund, this ecotourism, travel for the purpose of observing wildlife and learning about the environment, generated approximately one billion dollars in 2000.
The International Whaling Commission, set up in 1946 by twenty countries, has attempted to monitor and establish limits on the number of whales and the kinds of whales that are killed each year. In 1972, the United States Congress passed the Marine Mammal Protection Act banning hunting of marine mammals and the purchasing of their products from other countries. While these efforts have brought an end to most whale hunting worldwide, they may have been too late for many rorqual species. Today, the blue whale, the sei whale, and the fin whale are considered Endangered, facing a very high risk of extinction in the wild. Humpback whales are considered Vulnerable, facing a high risk of extinction in the wild. Studies done by the International Whaling Commission have estimated that there are fewer than five hundred blue whales remaining in the world.