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Blue Whale
A vulnerable underwater heavyweight
Common Name: Blue whale, Sibbald's rorqual, sulphur bottom whale; Baleine bleue, baleine d'Ostende, baleinoptère bleu, rorqual bleu, rorqual à ventre cannelé, rorqual de Sibbold (Fr); Ballena azul, rorcual azul, rorqual de Sibbold (Sp)
Scientific Name: Balaenoptera musculus
Location: All oceans
Population: Between 3,000-5,000 individuals
Background
The blue whale is the largest animal ever known to have existed. During the 20th century, the species was an important whaling target and even after it was protected and commercial whaling stopped in 1964, exploitation efforts by the former Soviet Union persisted.
Although commercial whaling no longer represents a threat, global climate change and its impact on ocean euphausiids (krill - shrimp-like crustaceans), blue whales' major prey, makes this cetacean particularly vulnerable.
A number of South Pacific countries, including five island nations, have declared their EEZs (Exclusive Economic Zone) to be whale sanctuaries in which commercial whaling is prohibited and where additional research on large whales is encouraged.
WWF and blue whales
© WWF - Canon / Pieter LAGENDYK
WWF efforts in this area over the coming years will be directed towards increasing awareness of the need for cetacean conservation at the national and regional levels, and to create opportunities for local communities to be involved in, and to profit from, cetacean conservation initiatives.
Physical Description
The blue whale is the largest animal that has ever lived on earth. Its heartbeat can be detected from two miles away and its heart is the size of a Volkswagen Beetle. Its stomach can hold one ton of krill and it needs to eat about four tons of krill each day. It is identified by a relatively small dorsal fin, a fairly rounded rostrum (anterior part of the skull), and approximately 90 ventral grooves which reach the navel.
Blue whales have row of 300- 400 baleen plates on each side of the mouth, which are black in color and range in length from 20 inches in front to 40 inches in back.
The species dives for 10 - 20 minutes periods, and usually feed at depths of about 300 feet. Average travel speed is around 13 m/hr, although they may swim as fast as 29 m/hr if they perceive a danger. To communicate, they emit low-frequency sounds and series of clicks.
Blue whales are believed to have excellent hearing, especially at low frequencies, which is valuable in the dark ocean environment. They are the loudest animals on Earth and louder than a jet engine: their calls reach 188 decibels, while a jet reaches 140 decibels. Their low frequency whistle can be heard for hundreds of miles, and is probably used to attract other blue whales.
Blue whale populations migrate towards the poles, into cooler waters, in the summer to feed. They migrate back towards the equator, into warmer waters, in the winter to breed. Because the seasons are opposite in the Northern and Southern Hemispheres, the net result of these movements is that the Northern Hemisphere and Southern Hemisphere stocks do not mix.
Size
The largest recorded length for a blue whale is 110 feet, but sizes tend to run more in the range of 80-100 feet. Females are up to 32 feet longer than males. At 100 feet, a blue whale would weigh close to 200 tons, or 400,000 pounds.
Color
Blue whales are a lightly mottled blue-grey, with light grey or yellow-white undersides. The yellowish ventral coloring is due to the accumulation of diatoms (microscopic, unicellular marine algae) in colder water, and has inspired the nickname "sulphur bottom whale."
Habitat
Range States
Argentina, Australia, Bangladesh, Canada, Cape Verde, Chile, Ecuador, Falkland Islands (Malvinas), French Polynesia, French Southern Territories, Greenland, Iceland, India, Indonesia, Iraq, Japan, Kenya, Democratic People's Republic of Korea, Republic of Korea, Malaysia, Mexico, Myanmar, Namibia, New Zealand, Nicaragua, Norway, Pakistan, Panama, Peru, Russian Federation, South Africa, Spain, Sri Lanka, Svalbard and Jan Mayen, Taiwan, Province of China, United Republic of Tanzania, United Kingdom, United States, Uruguay
Geographical Location
All oceans
Ecological Region
Antarctic Peninsula and Weddell Sea, Bering-Beaufort-Chukchi Seas, Barents-Kara Seas, Mediterranean Sea, Northeast Atlantic Shelf Marine, Grand Banks, Yellow Sea, Okhotsk Sea, Patagonian Southwest Atlantic, Southern Australian Marine, New Zealand Marine, California Current, Benguela Current, Humboldt Current, Agulhas Current, Western Australia Marine Panama Bight, Gulf of California, Galapagos Marine, Canary Current, Nansei Shoto, Sulu-Sulawesi Seas, Bismarck-Solomon Seas, Banda-Flores Sea, New Caledonia Barrier Reef, Great Barrier Reef, Lord Howe-Norfolk Islands Marine, Palau Marine, Andaman Sea, Tahitian Marine, Hawaiian Marine, Rapa Nui, Fiji Barrier Reef, Maldives, Chagos, Lakshadweep Atolls, Arabian Sea, East African Marine, West Madagascar Marine, Mesoamerican Caribbean Reef, Greater Antillean Marine, Southern Caribbean Sea, Northeast Brazil Shelf Marine.
Interesting Facts
The blue whale is bigger than 25 elephants; bigger than a Brontosaurus and a Tyrannosaurus rex combined.
It consumes about 40 million individual euphausiids daily, amounting to about 8,000 lbs.
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