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Whales
Comparative Size of Whales
Nearly 90% of cetacean species are toothed whales. Most toothed whales are small dolphins and porpoise, however there are a few large toothed whales such as the killer whale and the mighty sperm whale. Toothed whales are believed to be some of the most intelligent animals on earth. Dolphins as well as beluga and killer whales have demonstrated their intelligence while in captivity, and sperm whales possess the largest brain of any creature alive. The presence of teeth and one external blowhole distinguishes toothed whales from baleen whales. Also, most toothed whales use echolocation to locate food and "see" their environment.
Class:
Mammalia (Mammals)
Sperm whale Throughout history, humans hunted toothed whales for oil and food. Sperm whales were prized by commercial whalers for the large amount of oil that could be produced from their blubber and spermaceti organ and for ambergris (a waxy substance that forms around squid beaks in the whales' intestines), which was used to make perfume. Sperm whales are still classified as endangered because of the great numbers that were killed by commercial whaling through the 17th to early 20th centuries.
Baleen whales are very large, have paired blow holes, and characteristic baleen plates that they use to filter food. Baleen whales are the largest animals on earth, yet they feed on some of the smallest animals in the ocean. There are 12 baleen whale species divided into 4 families: right, pygmy right, gray and rorqual whales.
Right whales were called the "right" whales to catch by early hunters because they are large, swim slowly, have long baleen plates, contain lots of oil, and float when killed. Right whales do not have dorsal fins or throat grooves. The taxonomy of this family is rather confusing, but currently there are three species of right whales:
Northern right whale the Northern right whale,Southern right whale and bowhead whale. The pygmy right is in a separate family although it shares similar characteristics to right whales.
A Gray Whale at the Surface to Spyhop Photo taken by Dave Withrow, NMML
Gray whales have their own taxonomic family, genus, and species. They are the most coastal of the baleen whales and are often found within a few miles of shore. Each year gray whales migrate between their summer feeding grounds in the Bering, Chukchi, and Beaufort Seas to their winter breeding grounds off Baja California, Mexico. This is one of the longest migrations by a mammal species.
Gray whale Gray whales are gray in color and their skin is encrusted with barnacles and a unique species of small crustaceans known as "whale lice." They have 2-3 short throat grooves and instead of a dorsal fin they have a low dorsal hump followed by 6-12 "knuckles" or bumps. Whalers used to call gray whales "devil fish" because of their aggressive response to being hunted. Rorqual whales are relatively streamlined in appearance and have pointed heads and small pointed fins. They can be distinguished from other whales by many (25-90) deep groves along their throats that expand when they feed. The species of rorqual whalesare:
humpback whale
fin whale
Bryde's whale
Northern and Southern blue whale
northern minke Image Credits:FAO Fisheries Global Information System
antarctic minke, and Eden's ("small-type") whale. Antarctic minke whales are larger than their Northern Hemisphere counterparts, with females reaching a maximum length of 10.7 meters (35 feet) and males reaching 9.8 meters (32 feet). The maximum weight of adults is about ten tones (11 tons). Northern Hemisphere minke whales reach a maximum length of 9.2 meters (30 feet). Toothed whales have 1 to 65 teeth depending on the species and tend to be smaller than baleen whales. Toothed whales have a single blowhole and do not have baleen plates. There are several families of Odontoceti, or toothed whales, including sperm whales, pygmy sperm whales, beaked whales, river-dolphins (3 families) belugas and narwhals, dolphins and porpoises.
A Close-Up of a Sperm Whale Head and Blow Hole Photo taken by Rocky Beach, NMML The sperm whale is the most famous of the Physeteridae family. It is also the largest of the toothed whales and may dive deeper than any other cetacean. Herman Melville made the sperm whale famous in his classic novel Moby Dick. A similar toothed whale family is the Kogiidae family which includes the pygmy sperm whale and dwarf sperm whale which are significantly smaller than the sperm whale but share characteristics such as the spermaceti organ, the blunt head, and the distinctive narrow lower jaw. Beaked whales are members of the Ziphiidae family. The name Ziphiidae was derived from the Greek word "xiphos" meaning sword so beaked whales are the "sword-nosed whales." Beaked whales are the least well-known of all cetaceans. Some species have never been seen alive and have been studied only when dead animals wash ashore. Beaked whales may be rare or simply elusive but, generally, they live in deep water far from land and are rarely seen.
Sowerby's beaked whale Image Credit:FAO Fisheries Global Information System It is believed that there are 20 living species of beaked whales, including the North Pacific bottlenose whale, Shepard's beaked whale, Sowerby's beaked whale, and Stejneger's beaked whale. Threats Facing Whales Whaling Whaling started in the first few centuries A.D. by the Japanese, and between about 800 and 1000 A.D. by the Norwegians and by the Basque people living on the north coast of France and Spain.
The Dutch, British and Americans started in the 17th century. All of this early whaling was done from small boats using hand-thrown harpoons. Most of the whalers hunted the slow and docile Northern Right Whale, so named because it was the "right whale" to hunt. The Europeans wanted the whales for their oil and for their baleen. The Japanese ate the meat, and found uses for many other parts of the whale.
Modern whaling began in 1868, when the harpoon gun and explosive harpoon (which explodes inside the whale) were invented. The harpoon guns were mounted on fast steam-driven vessels, making it possible to catch the faster-swimming rorquals (blue, fin, Sei, and Minke whales). The development of factory ships made it possible for the whalers to stay at sea for long periods, increasing the number of whales they could hunt. Whaling has been regulated by the International Whaling Commission (IWC) since 1946. The IWC gave its member nations quotas on the whales they wanted to hunt, based on negotiations and guesswork. The quotas were always too high, so the populations declined rapidly. After the biggest whales (blues) were hunted to the point that they were too hard to find, the whalers went on to the next largest species, the fin whale. Then they moved on to the Sei whale, then the Minke, and humpbacks were also taken. The blue whale population was estimated at 250,000 in 1920 but has been reduced by 96%, and the fin whale population, previously estimated at 600,000, has been reduced by 92%. Humpback and Sei whales were also hunted down to a small percentage of their original populations. The IWC is open to non-whaling nations as well as whaling nations. n 1982 the IWC was able to adopt a resolution calling for an indefinite moratorium on commercial whaling, which became effective in 1986. There are also some loopholes in the IWC Moratorium. First, compliance with the moratorium is voluntary: any IWC member country can file a protest of the moratorium, and then need not abide by it: Norway is hunting Minke whales in the North Atlantic under such a protest. Second, there are exceptions for "aboriginal whaling"; the American Eskimos are still allowed to hunt the bowhead whale and the gray whale, and the Russians are allowed to take 100-200 gray whales to serve to their northern aboriginals. Third, whaling "for scientific research" is still allowed. In 1994 the IWC was successful in setting aside a huge area around Antarctica as a Southern Ocean Sanctuary, which should protect about 90% of the world’s whales and their major feeding areas. The proposal passed by a vote of 23-1, with Japan casting the single opposing vote. Norway, Japan , Canada, Greenland, Russia, Denmark and Iceland continue whaling to various degrees. Japan has continued and expanded its whaling activities in spite of intense international pressure to abide by the moratorium and sanctuary resolutions. It has expanded its "research program" to include permits for 50 Bryde's and ten sperm whales in the North Pacific, along with a quota of Minke whales that was increased from 100 to 260 for the 2006 season. Another major problem in protecting whale species has been illegal whaling. So far, no species of whale has gone extinct because of whaling, but many species have been reduced to "commercial extinction" (too rare to be worth hunting), and many local populations, or "stocks", have been eliminated. Bycatches in fisheries Direct hunting and bycatch remain the greatest threats to the survival of these graceful aquatic mammals. Recent analysis has shown that around 300,000 small whales, dolphins, and porpoises die each year (about one every two minutes) as a result of becoming entangled in fishing gear. Known as bycatch, this accidental catch is one of the greatest threats to the survival of many cetacean populations. Many whales get caught up in large scale high seas drift nets and over the past 25 years this has become a serious threat. In 1993 the UN establishes a Global moratorium on large-scale driftnets outside the 200 mile Exclusive Economic Zones. The only problem is that this needs to monitored closely. Habitat Degradation Vessel traffic, riverbank development, damming and irrigation projects can seriously injure whales causing populations to start declining. Chemical Pollution These are the greatest threat the survival of whales. It is the effect of industrial chemicals and pesticide run-off that are the most important threats. The chemicals gather in the whales blubber while they feed heavily in the summer months. These are then released into their milk when they migrate to the winter calving grounds, where there is little food.
Noise Pollution Whales depend on sound for navigation and communication for finding food. Both traffic and industrial activity can increase underwater noise which can reduce the whales' ability to communicate. Global Climate change An increase in surface water temperature is linked to a decline in zooplankton which will affect all species that depend on it. Also higher levels of solar radiation caused by the reduction in stratospheric ozone has led to declines in phytoplankton production which is the basis of the entire food chain in the ocean. Accidents and Disturbance. Many Northern right whales in North Atlantic have scars from boat propellers so we need to make sure boat traffic is regulated and the whales are protected from harassment. Credit: The National Marine Mammal Laboratory, FAO Fisheries Global Information System, The Illinois State Academy of Science, American Cetacean Society, School of Biological Sciences, University of California , The United States Navy |
