76.
Blue Whale
(Balaenoptera musculus)
EN
Overview
The largest mammal ever known to have existed. The species is thought to feed almost exclusively on krill (small, shrimp-like crustaceans). In the summer feeding areas, individuals may consume as much as 4 tonnes of krill each day. Blue whales have the deepest voice of any animal, and their vocalizations carry for thousands of miles underwater, allowing them to communicate across vast oceans at frequencies below the range of human hearing. For centuries the blue whale was safe from exploitation because of its sheer size and speed. However, the species was driven to the brink of extinction following the development of modern whaling techniques.
Urgent Conservation Actions
Continued protection and close monitoring. Areas of critical habitat must be identified and protected. Further research into ecology and threats to inform conservation programmes.
Distribution
All the major oceans of the world.
Media from ARKive
ARKive video - Blue whale- overview
ARKive image - Female blue whale with calf
ARKive image - Blue whale calf breaching
ARKive video - Blue whale fluke
ARKive video - Blue whale feeding on krill
ARKive image - Blue whale calf breaching
ARKive video - Blue whales at surface
ARKive image - Blue whale mother and calf at the beginning of a dive
ARKive image - Four blue whales, including calf, socialising
ARKive image - Blue whale calf feeding on Krill, mother in background
ARKive image - Blue whale underwater
ARKive image - Blue whale
ARKive image - Blue whale fluke
ARKive image - Blue whale skeleton
ARKive image - Aerial view of blue whale
ARKive image - Blue whale, aerial view
ARKive image - Blue whale surfacing, blow holes and spine visible
ARKive image - Remora attached to a blue whale
ARKive image - Blue whale, whalebone plates
ARKive image - Blue whale, close up of skin showing distinctive mottled pattern
Evolutionary Distinctiveness
Order: Cetacea
Family: Balaenopteridae
Early cetaceans are known from 50 million year old fossils found in India and Pakistan, along the ancient Tethys Sea which separated Africa from Asia and southern Europe. These early members of the cetacean clade (Ambulocetus, Indocetus, Pakicetus and Rodhocetus) were dolphin-sized amphibious mammals called archaeocetes, which vaguely resembled something between an otter and a crocodile. They had reduced hind limbs, but probably propelled themselves through the water using up-and-down movements of a strong tail, as do living cetaceans. It was long thought that these early whales were closely related to an extinct group of primitive carnivorous mammals called mesonychids, but molecular data now indicate that cetaceans are most closely related to hippos. Cetaceans are now grouped together with artiodactyls in a new clade, Cetartiodactyla. Around 50-35 million years ago the archaeocetes diversified and spread into deeper oceanic waters, with genera such as Basilosaurus and Dorudon well represented in the fossil record. By 30 million years ago, most of the archaeocetes were extinct, and two distinct new suborders had evolved, the mysticetes (baleen whales) and odontocetes (toothed whales). The living mysticetes are filter feeders, with baleen plates instead of teeth. They comprise 4 living families (the Balaenidae, Balaenopteridae, Eschrichtiidae and Neobalaenidae). The Balaenopteridae (rorqual family) comprises at least 7 species, including Bryde’s whale, humpback whale, minke whales, fin whale, sei whale and blue whale. The taxonomy of many of these species is complex, and there may be several more closely related species waiting to be recognised. The blue whale is believed to have diverged from the fin whale around 5 million years ago (shortly after humans diverged from chimpanzees). Remarkably, these two species have been known to hybridise.
Description
Size: 
Head and body length:
Male: 25 m (Antarctic average)
Female: 27 m (Antarctic average)
Weight: up to 190,000 kg
The blue whale is the largest animal ever known to have existed. Its long, streamlined body can reach lengths of up to 34 m, almost as long as a Boeing 737. The skin is greyish-blue in colour with light grey mottling on the back. The underparts are the same colour, but sometimes acquire a yellow coating of species-specific micro-organisms (diatoms), which led to the early whalers giving the species the name “sulphur bottom”. The species has a pointed snout and a very broad, flat rostrum (upper part of head). Its dorsal fin is relatively small, reaching a height of only 33 cm. Blue whales have around 90 throat grooves extending to the navel. These grooves allow the throat to expand enormously during feeding. On each side of the upper part of the mouth is a row of 300-400 black baleen plates. The blow (or spout) of this species is the largest of all the whales, reaching heights of up to 9 m.
Ecology
The species is usually seen alone or in small groups of two to three individuals, although aggregations of up to 60 may form in areas where food is plentiful. Blue whales are migratory, with most individuals spending the summer feeding in high-latitude regions and returning to warmer waters in the winter for mating and calving. Since the seasons are reversed in the two hemispheres, the northern and southern populations migrate to areas of low latitude at different times of the year and thus remain separate. Some individuals are thought to remain at low latitudes year round in certain parts of the Indian and Pacific Oceans. The species is thought to feed almost exclusively on small, shrimp-like crustaceans (euphausiids), commonly called krill. To feed, the animals take in large amounts of water and krill and then force the water out through their baleen plates, leaving food trapped on the inner fibres of the baleen. Most feeding takes place at depths of less than 100 m, with dives typically lasting between 10 and 20 minutes. In the summer feeding areas the whales may consume as many as 40 million krill each day, a total weight of 3,600 kg. During the rest of the year the whales do not feed, and appear to live off stored fat. Females give birth every 2-3 years during the winter, in the warmer, low latitude waters. A single calf (rarely twins) is usually born after a gestation period of around 10-12 months. Calves are 7 m long at birth, and weigh around 2,000 kg. They grow rapidly, gaining 90 kg per day until they are weaned after 7-8 months, when they are about 15 m long. Sexual maturity is reached at 5-10 years. Blue whales are thought to live around 80-90 years, although some individuals are estimated to have lived for up to 110 years. The species has virtually no natural predators, although calves may be vulnerable to killer whales or large sharks.
Habitat
Inhabits the open ocean in both cold and temperate waters. Often found along the continental shelf edge and near polar ice.
Distribution
Occurs in the Arctic, Atlantic, Indian and Pacific Oceans, from the tropics to the drift-ice of polar waters. There are three main populations: one in the North Pacific (B. m. musculus: North Pacific stock), another in the North Atlantic (B. m. musculus: North Atlantic stock) and a third in the Southern Hemisphere (consisting of B. m. intermedia and B. m. brevicauda).
Population Estimate
It is thought that fewer than 5,000 individuals remain.
Population Trend
Increasing.
Status
Classified as Endangered (EN A1abd) on the 2010 IUCN Red List of Threatened Species. The subspecies have been classified as follows:

B. m. musculus: (North Atlantic stock) Vulnerable (VU D1). This population is believed to number no more than 1,500 individuals.
B. m. musculus: (North Pacific stock) Low Risk/conservation dependent (LR/cd). This population was estimated at about 2,000 in the early 1990s, with evidence suggesting an increase off the coast of California.
B. m. intermedia (southern blue whale): Endangered (EN D). There could be as few as 250 individuals surviving.
B. m. brevicauda (pygmy blue whale): Listed as Data Deficient (DD) because of uncertainty about its taxonomic status.
Threats
Blue whales were not initially targeted by early whalers because of their enormous size and speed, and the fact that they are so difficult to locate. However, technological advances towards the end of the nineteenth century made capture possible. The whaling industry began to focus on blue whales after 1900, and by the 1960s so many had been killed that the species was pushed to the edge of extinction. More than 360,000 blue whales were taken by whaling fleets in the Southern Hemisphere from 1904 to 1967, when they were given legal protection. More than 8,000 pygmy blue whales were killed but not reported at the time by Soviet whaling fleets in the 1960s and 1970s. Although commercial whaling of the species is now banned, the population is now so small that any further mortalities may severely impact on the survival of the species. The species is still subject to a number of threats, including noise and chemical pollution. The blue whale’s almost total dependence on krill means that it could be vulnerable to major changes in ocean productivity caused by factors such as climate change. There is concern over Japan’s continued hunting of whales for “scientific purposes” as blue whale meat sometimes turns up for sale in markets in Japan.
Conservation Underway
Commercial whaling of the species has been banned since 1966, and all international trade in the species is prohibited as a result of its listing on Appendix I of CITES (the Convention on International Trade in Endangered Species) and Appendix I of the Convention on Migratory Species (CMS or the Bonn Convention). The species occurs in a number of protected areas throughout its range aimed at protecting the whole ecosystem, and there are whale sanctuaries in the Antarctic, Indian and Southern Oceans. Blue whales are covered by a number of international agreements and several countries have implemented research and conservation programmes for the species. These include identifying areas of critical habitat, investigating species abundance and distribution, and mitigating the threats to the species. The IWC is the co-ordinating body for whale research and conservation.
Projects
Conservation Proposed
Blue whales require continued protection and close monitoring into the foreseeable future. Knowledge of blue whales is severely limited by their lack of accessibility for research. Further research into the ecology and threats facing this species is required. International cooperation needed to save this species. Areas of critical habitat should be identified and protected, and the immediate threats must be addressed. Recovery strategies should focus on managing human activities (including fisheries, vessel traffic, whale watching, and activities that cause cetacean habitat degradation and loss) to mitigate negative impacts on the species. International co-operation is essential to the successful recovery of the blue whale. Brazil and Argentina have proposed to establish a sanctuary in the South Atlantic, and New Zealand and Australia hope to create a new South Pacific Sanctuary. Both sanctuaries would provide protection for the southern populations of blue whales, along with many other species. In order to be created, these sanctuaries must be voted for by a majority of the member nations of the IWC.
Associated EDGE Community members

Anouk has been carrying out cetaceans surveys since 1985

Links
Ocean Alliance - Whale Conservation Institute (WCI)
This institute was established in order to protect whales and their ocean environment through scientific research and education.

Whale and Dolphin Conservation Society (WDCS)
The WDCS is the global voice for the protection of whales, dolphins and their environment.

UK Biodiversity Action Plan: Grouped Plan for Baleen Whales
This UK collaborative effort aims to monitor, assess and develop a strategic plan to ensure the long term survival of the blue whale.
References

ARKive. (Oct 2006).

Cetacean Specialist Group. 1996. Balaenoptera musculus. In: IUCN 2006. 2006 IUCN Red List of Threatened Species. Downloaded on 25 July 2006.

Clapham, P. J., Young, S. B. and Brownell, R. L. Jr. 1999. Baleen whales: conservation issues and the status of the most endangered populations. Mammal Review 29(1): 35-60.

International Whaling Commission (IWC)

Nowak, R. M. 1999. Walker’s Mammals of the World. Sixth edition. The Johns Hopkins University Press. Baltimore and London.

Reeves, R. R., Smith, B. D., Crespo, E. A. and di Sciara, G. N. (Compilers). 2003. Dolphins, Whales and Porpoises: 2002-2010 Conservation Action Plan for the World’s Cetaceans. IUCN/SSC Cetacean Specialist Group. IUCN: Gland, Switzerland.

Reilly, S.B., Bannister, J.L., Best, P.B., Brown, M., Brownell Jr., R.L., Butterworth, D.S., Clapham, P.J., Cooke, J., Donovan, G.P., Urbán, J. & Zerbini, A.N. 2008. Balaenoptera musculus. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4. www.iucnredlist.org. Downloaded on 14 November 2010.

Reilly, S.B., Bannister, J.L., Best, P.B., Brown, M., Brownell Jr., R.L., Butterworth, D.S., Clapham, P.J., Cooke, J., Donovan, G.P., Urbán, J. & Zerbini, A.N. 2008. Balaenoptera musculus. In: IUCN 2009. IUCN Red List of Threatened Species. Version 2009.2. <www.iucnredlist.org>. Downloaded on 16 February 2010.

Whale and Dolphin Conservation Society (WDCS)

Distribution map based on data provided by the IUCN Global Mammal Assessment.

if you can provide new information to update this species account or to correct any errors, please email us at info@edgeofexistence.org


Forum comments
  1. abort
    Member

    well realy like the blue whales its awesome.

    Posted 3 years ago #
  2. Sharks
    Member

    Looks like sharks are now going the why of the whales, soon we will be running out of things to kill.

    Posted 4 years ago #
  3. Anonymous
    Unregistered

    They are amazing! Wotchd this nature prog with David A I think and they showed killer whales trying to kill a baby blue whale so sad :(

    Posted 5 years ago #
  4. Anonymous
    Unregistered

    whales r wierd

    Posted 5 years ago #
  5. Anonymous
    Unregistered

    i luv whales!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

    Posted 5 years ago #
  6. Anonymous
    Unregistered

    aww bless there huge fins...
    im doin a science (biology of course) gcse task that requires me to do a leaflet on an endangered species of whale so i chose blue whale.. its so sad:( that people shot them with harpoons because a wide range of products such as soap and oil could be made from whale body parts. i mean why would you want whale flavoured soap, or shampoo with 'whale extracts'?? it is inhuman. we ♥ the blue whale xxx

    Posted 5 years ago #
  7. haha sadly never! :-)

    Posted 5 years ago #
  8. Anonymous
    Unregistered

    has any one seen a blue whales penis there hugeeeee

    Posted 5 years ago #
  9. Anonymous
    Unregistered

    we love blue whalessss

    Posted 5 years ago #

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