CETÁCEOS
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Cetáceos Los Cetáceos (Cetacea, del griego ketos, "ballena" y del latín aceum, "relación o la naturaleza de algo") son un orden de mamíferos placentarios que incluye a las ballenas, cachalotes, zifios, delfines, orcas y marsopas. El orden está constituido por unas ochenta especies vivientes clasificadas en 42 géneros asignados a 11 familias. Los cetáceos actuales se reparten entre dos subórdenes: Mysticeti (ballenas con barbas, que se alimentan filtrando el agua) y Odontoceti (animales cazadores, con una dentición de dientes iguales que se aparta mucho de lo que es característico de los mamíferos). El término ballena designa en principio a todos los misticetos, aunque en sentido estricto se reserva a los integrantes de la familia balénidos; para el resto se utiliza el término rorcual. En ocasiones se emplea el término ballena para miembros del suborden Odontoceti, como cuando se llama ballenas asesinas a las orcas, o cuando, como en Moby Dick, se trata de ballena a lo que, según la descripción, es un cachalote (llamado sperm whale, ballena del esperma, en inglés). Muchas especies de cetáceos han sido cazadas carne, su grasa (utilizada para producir aceite cachalotes), usado para perfumes. El Convenio Ballenas (ICRW), en vigor desde 1948, regula Comisión Ballenera Internacional (IWC).
hasta el borde de la extinción, para obtener su para lámparas) o el ámbar gris (propio de los Internacional para la Regulación de la Caza de la explotación de cetáceos, administrado por la
Evolución Los cetáceos evolucionaron a partir de mamíferos terrestres de hábitos anfibios, probablemente durante el Eoceno, entre 55 y 34 millones de años atrás. Las pruebas más recientes confirman una vieja hipótesis según la cual los cetáceos evolucionaron a partir de miembros del orden artiodáctilos, el mismo que incluye a vacas, antílopes, ciervos, cerdos e hipopótamos. Muchas de las especies fósiles más antiguas de cetáceos se clasifican en un orden específico: los arqueocetos (Archaeoceti). En 2001, dos importantes fósiles incompletos de 47 millones de años de antigüedad, llamados Rodhocetus balochistanesis y Artiocetus clavis, fueron hallados en Baluchistán (Pakistán). Estos fósiles representan formas intermedias entre ungulados terrestres y ballenas, y son evidencia de que los parientes más cercanos de las ballenas en ambientes terrestres debían ser parecidos a los hipopótamos, aunque las pruebas de ADN no permiten asegurar que éstos lo sean de hecho. Sin embargo la filogenia de los hipopótamos actuales se remonta a tan solo unos 15 millones de años por lo cual queda descartada una evolución directa desde los hipopótamos hasta los cetáceos, según Hans Thewissen en un informe publicado en Nature (diciembre de 2007) un pequeño artiodáctilo de hace 48 millones de años, el Indohyus (semejante al actual hiemosco o «ciervo-ratón africano») habría iniciado el linaje de los cetáceos; como el hiemosco, el Indohyus aunque bien adaptado a la marcha terrestre, frecuentemente, ante sus posibles predadores, se refugiaba en medios acuáticos, es probable que sucesivas mutaciones en el genoma dieran especies transicionales semejantes primeramente a los actuales hipopótamos y luego a los actuales sirenios hasta llegar a especies altamente adaptadas al medio acuático, por ejemplo la Pakicetus attocki es el registro fósil de ballena más antiguo que se conoce en el año 2007, efectivamente hace unos 35 millones de años los ancestros marinos de los actuales cetáceos perdieron definitivamente sus patas las cuales por convergencia evolutiva se transformaron adaptativamente en aletas o quedaron como pequeños y atrofiados huesos vestigiales. Los cetáceos son mamíferos, y como todos los demás representantes de esa clase, respiran aire con los pulmones, son de sangre caliente (más precisamente son endotérmicos), amamantan a sus crías y tienen pelo (aunque muy vestigial). Presentan un característico alargamiento del rostro y una migración de la nariz hacia la parte superior de la cabeza. Los misticetos tienen dos orificios nasales y los odontocetos solo uno. Características Los cetáceos son los mamíferos mejor adaptados al medio acuático; el cachalote por ejemplo, pueden permanecer bajo el agua hasta dos horas con una sola inspiración y alcanzar profundidades de 2.800 m. Los misticetos no tienen dientes, pero poseen unas placas queratinosas llamadas barbas o ballenas, utilizadas como tamiz para retener peces y crustáceos, de los cuales se alimentan. Las barbas no son estructuras homólogas a los dientes, pero su origen es tegumentario. El tipo de estructura bucal (barbas en los misticetos y dientes en los odontocetos) está relacionado con el tipo de dieta; los misticetos son filtradores (bocas grandes, anchas y barbas) mientras que los odontocetos (bocas finas y dentadas) son cazadores. Las costillas son libres (no unidas ventralmente al esternón), lo que les permite una gran plasticidad del volumen pulmonar. Los
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miembros anteriores están modificados en aletas, el tren posterior ha desaparecido completamente y los huesos de la cadera son vestigiales o inexistentes. La cola es muy fuerte y musculosa y termina en una aleta horizontal usada para propulsarse. Algunas especies tienen una aleta dorsal. En general tienen un gran repertorio "vocal". Los misticetos usan el sonido principalmente para comunicarse entre ellos; pero los odontocetos emplean adicionalmente la gama de frecuencias altas a modo de sónar. La ballena azul (Balaenoptera musculus) es especialmente notoria por ser el mamífero más grande de cuya existencia tengamos conocimiento. Puede alcanzar los 30 m de largo y 180 t de peso. Taxonomia Existen alrededor de ochenta especies, que se dividen en tres subórdenes, uno de ellos extinto (Archaeoceti).
Suborden
Superfamilia
Familia
Subfamilia
Balaenidae
Ballenas francas y ballena de Groenlandia Balaenopterinae
Rorcuales
Megapterinae
Ballena jorobada o Yubarta
Balaenopteridae
Mysticeti Cetáceos con barbas
Platanistoidea Delfines de río Odontoceti Cetáceos dentados
Descripción
Eschrichtiidae
Ballena gris
Neobalaenidae
Ballena pigmea
Delphinidae
Delfines oceánicos y orcas
Iniidae
Delfín del Amazonas o Boto
Lipotidae
Delfín del Yangtze o Baiji
Platanistidae
Delfines del Ganges y el Indo
Pontoporiidae
Delfin del Plata o Franciscana
Phocoenidae
Marsopas
Physeteridae
Cachalote
Kogiidae
Cachalotes enano y pigmeo
Ziphiidae
Berardios y zifios
Monodontidae
Beluga y Narval
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Suborder: Mysticeti Family: Balaenidae Other Names: Black Right Whale, Right Whale (bothe species), Biscayan Right Whale (Northern Right Whale). The Southern Right Whale (Eubalaena australis) Northern Right whale (Eubalaena glacialis) Right Whales were regarded by Nineteenth century whalers as the 'right' whales for their industry. They were easy to approach, lived close to shore, floated when they were dead, and provided large quantities of valuable oil, meat, and whalebone. There are only minor cranial differences between the northern and southern hemisphere species, and it is suggested that southern whales have more callosities on top of their lower lip and fewer on top of the head.
Right Whales are slow, lumbering, skimmer-feeders. They are surprisingly acrobatic and may be seen waving their flippers above the surface, breaching, lobtailing, and flipper-slapping. Southern Right Whales will also "head-stand", waving their flukes high in the air for up to 2 minutes. They sometimes raise their flukes at right angles to the wind and use them as sails. This allows them to be blown along through the water and appears to be a type of play as they will often swim back and do it again. Their baleen plates are narrow, up to 2 metres long, and vary from dark brown to dark grey or black, though it can appear yellowish underwater. The baleen is used to filter out plankton and krill (small shrimp-like crustaceans) as they cruise along the surface. They seldom reach a speed of 9km/hr. and take over a month to swim the 5000 km or so distance from the sub-Antarctic waters. Right Whales migrate to warmer temperate waters to give birth and mate. They also teach their young how to swim in the warm sheltered waters. The new-born calves have virtually no blubber to insulate them from the cold. They are fattened on rich whale milk which has a 40% fat content. This produces spectacular results and whale calves may double their weight within a week. However, there is no food in these warmer waters for the mothers, who must fast while they raise their young. Most births occur in early winter, after which the adults begin their courtship displays of breaching, tail splashing, jostling and caressing.
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Calves stay close to their mothers, suckling for a year or less and playing together. Calves learn skills they need to survive in one of our planet's great wilderness areas, the Ocean. By the 1860's Right Whale numbers were so severely depleted that whalers could no longer hunt them profitably. From an estimated world population of 100,000 whales, 30,000 were taken from Australian and New Zealand waters alone. Today the world population numbers about 2,000 of which 500 visit southern Australian waters to mate and breed. It is feared that the eastern American stock, now less than 300, is in great danger of extinction due to the accidental deaths of right whales involved in shipping accidents. It may never recover and it may already be doomed to extinction. All Right whales are protected internationally under the convention for the regulation of whaling and have not been actively hunted since 1935.
Suborder: Mysticeti Family: Balaenopteridae Subfamily: Balaenopterinae There are 3 different subspecies: balaenoptera musculus - Northern Hemisphere balaenoptera intermedia - Southern Hemisphere balaenoptera brevicauda - Tropical Southern Hemisphere Other Names: Sulphur-bottom, Sibbald's Rorqual, Great Northern Rorqual The Blue Whale (Balaenoptera musculus) The Blue whale is, and always has been, the largest animal ever to exist on earth. This whale can grow to a length of 33m (110ft) and weigh 190 tonnes but on the average it is much smaller. The Blue whale is called a "rorqual" a Norwegian word for "furrow" and refers to the pleated grooves running from its chin to its navel. The throat grooves, in addition to streamlining the shape of the whale, allow the throat area (cavum vent-rale) to expand tremendously during feeding, and can hold 1,000 tons or more of food and water when fully expanded. By taking tonnes of water into its mouth and filtering out the fish or krill with its baleen plates a medium-sized Blue whale can eat over 4 tons of krill a day.
The head of the Blue whale forms up to a quarter of the total body length and compared with other rorquals is very broad. It has twin blowholes with exceptionally large fleshy splashguards to the front and sides. The baleen plates in the mouth of the Blue whale can be 90cm-1m (35-39in) in length the longest of all the rorquals but not the longest of all whales. Most Blue whales live in the Southern Hemisphere while smaller populations inhabit the North Atlantic and North Pacific. They migrate long distances between low latitude winter mating grounds and high latitude summer feeding grounds and are often seen in parts of California, Gulf of California (Sea of Cortez), Gulf of St. Lawrence, Canada and the northern Indian Ocean.
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Before mans intervention there were 228,000 Blue whales swimming the oceans of the world. Between 1904 and 1978, whalers scoured the seas for this huge cetacean, most were taken in the southern hemisphere, many against the law. Current figures suggest that a mere 11,700 animals are left. As the population figure suggests, it was ruthlessly and relentlessly slaughtered for every reason imaginable, almost to the point of extinction. Now on the endangered list, the Blue Whale is protected (since 1967) worldwide by international law. It is not to be hunted by anyone for any reason at all. Suggestion are that some populations may never recover.
Suborder: Mysticeti Family: Balaenopteridae Subfamily: Balaenopterinae Other Names: Tropical Whale The Bryde's Whale (Balaenoptera edeni) The Bryde's whale is a baleen whale and is unique in having 3 longitudinal ridges on its head, forward of the blowhole, while all other rorquals have just one. The whale can grow to a length of 12.5m (41ft) to 14m (46ft) and a weight of 26 tonnes with the female larger than the male. There has often been confusion between the Sei whale and the Bryde's whale as they are similar in both size and appearance. The head of the Bryde's whale at close range is unmistakable because of its three longitudinal ridges. The ridges are normally 1 - 2cm (.5 - .75in) high but the two outer ridges may not be as prominent and do not reach the tip of the snout. At their other ends, near the blowhole, they disappear from the surface and change into grooves of varying lengths. The grooves may be absent in some indiduals but the central ridge is continuous.
Although usually dark grey in colour some Bryde's have a lighter grey area between the head and the dorsal fin over the back and occasionally as a band down the flanks. The chin a belly are said to be white. The whale's 40 - 70 throat groves may be yellowish white in some areas and usually end at or behind the navel. The flippers are relatively short at only one-tenth of its body length. The skin on the underside towards the tail may be light purple-grey, blue-grey or creamy grey and may appear mottled with circular scars caused by parasites or Cookie-cutter sharks. The flukes are broad, distinctively notched and have a slightly concave trailing edge. The Bryde's whale has twin blowholes with a low splashguard to the front. It has no teeth but in their place are two row of baleen plates. The plates which number 250 - 410 are short and wide, with a maximum length (excluding bristles) of 50cm (20in) and a width of about 19cm (7.5in). The left and right rows of baleen plates may be separated by a gap at the front of the mouth. The baleen colour varies between individuals with most being black or slate-grey, though the plates near the rostrum are often completely or partially creamy white and sometimes with grey stripes. Baleen bristles are long, stiff, uncurled and generally brownish or greyish in colour. The Bryde's whale has a prominent dorsal fin which is relatively tall (though smaller than the Sei whale), strongly sickle-shaped, and situated about two thirds along the back. The trailing edge is sometimes notched or frayed. There may be 2 distinct groups in some areas one occurring offshore and partially migratory and the other living inshore and resident all year-round. The two forms differ slightly in their
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reproductive behaviour and the offshore animals are usually larger, have more scaring and have longer and broader baleen than the inshore variety. There may also be a 'dwarf' form around the Solomon Islands. The Bryde's whale prefers water temperatures above 20°C (68°F) so it is most common in coastal areas of tropical and subtropical waters of all seas. Some tropical populations are possibly sedentary with most migrating short distances with no known long-distance migrations to higher latitudes. Bryde's range in the Pacific from Japan and southern California south to northern New Zealand and Chile. In the Atlantic, southeastern United States and the Strait of Gibraltar south to Brazil and beyond the southern tip of South Africa. They range throughout most of the Indian Ocean. Some Bryde's whale populations have been depleted by whaling. Japan continued killing Bryde's whales until 1987. In that year three companies were operating a total of five catcher boats ranging from 400 to 600 tons, and took 200 sperm whales and 317 Bryde's whales. Although not on the Endangered list, the Bryde's Whale is protected (since 1986) worldwide by the Moratorium on Whaling. It should not to be hunted by anyone for any reason at all.
Suborder: Mysticeti Family: Balaenopteridae Subfamily: Balaenopterinae Other Names: Finback, Finner, Finfish, Common Rorqual, Razorback, Herring Whale. The Fin Whale (Balaenoptera physalus) The Fin whale is the second largest animal after the Blue Whale. It can grow to a length of 26m (85ft) and weigh 30-80 tonnes but on the average it is much smaller. The Fin whale is called a "rorqual" a Norwegian word for "furrow" and refers to the pleated grooves running from its chin to its navel. The throat grooves, in addition to streamlining the shape of the whale, allow the throat area (cavum vent-rale) to expand tremendously during feeding. This allows the taking in of tonnes of food-laden water which is then discarded through their baleen plates leaving the fish or krill for swallowing. This efficient system enables the largest animals on earth to feed on some of the smallest.
The head of the Fin whale is flattish and can be between one-fifth and one-quarter of the total body length. A distinctly ridged tailstock gave rise to the whaler's name 'razorback'. On some animals the white of the right side can continue onto the upper lip and to the side of the neck giving it a characteristic asymetrical appearance. It has twin blowholes with a single longitudinal ridge extending from the blowholes to near the tip of the snout. The baleen plates in the mouth of the Fin whale reach a maximum length of 70-90cm (28-35in) in length and a width of 20-30cm (812in). The baleen bristles are soft when compared with the Blue whale and vary from yellowish white to greyish white. Fin whales are most common in the Southern Hemisphere while smaller populations inhabit the North Atlantic and North Pacific. Some populations migrate between warm, low latitude winter mating grounds and cooler, high latitude summer feeding grounds though their movements are less predictable than other large whales. Some lower latitude populations, such as in the Gulf of
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California (Sea of Cortez) and Mexico seem to be resident all year round. In these areas they can be found in offshore waters but may be seen close to the shore where the water is deep. The Fin whale is the only rorqual commonly found in the Mediterranean. It is least common in the tropics and will enter polar waters, but not as often as Minke or Blue whales. Once one of the most abundant of the large whales, the Fin whale was heavily exploited by the whaling industry and its population has been severely depleted. The Fin was the first species to be hunted with the harpoon gun. Pre-whaling estimates indicate that there were 300,000-650,000 Fin whales swimming the oceans of the world. Current figures suggest that a mere 123,000 animals are left. Iceland was the last country to cease the killing of Fin whales. In 1989, Iceland was forced (financially) by worldwide public opposition to forestall it's Fin whale hunt. There are indications that Iceland is planning to kill 200 Fin whales annually as it believes this would be a sustainable harvest.
Suborder: Mysticeti Family: Balaenopteridae Subfamily: Balaenopterinae Other Names: Lesser Rorqual, Lesser Finback, Little Finner, Sharp-headed Finner, Pike whale, Little Piked whale, Pikehead. The Minke Whale (Balaenoptera acutorostrata) The Minke whale is the smallest of the rorquals. The male of the species can grow to a length of 9.8m (32ft) and the female larger at 11m (36ft) and weigh 10 tonnes. Populations in the Southern hemisphere on the average are slightly larger than other areas. Some animals are inquisitive and approach quite closely, but in most cases it is unusual to get a clear view. The Minke can be confused with the Sei, Bryde's, Fin or Northern Bottlenose whale, however, the dive sequence is distinctively different, the head is unscarred and it's mouthline is relatively straight.
The Minke whale has a slender streamlined body with a pointed head and often inconspicuous blow. The body is dark grey to black on the back, lightening to white on the belly and undersides of the flippers. There are often areas of light grey on the flanks, one just above and behind the flippers and the other behind the head. Individuals in the Northern hemisphere have a diagonal white band on the upper surface of each flipper. The head of the whale has an overall triangular shape, a single sharp longitudinal ridge along the top and forward of the blowhole and a narrow pointed snout. It has twin blowholes typical of all baleen whales. Baleen plates are found on each side of the upper jaw. The plates numbering between 230 to 360 are short 20-30cm (8-12in) in length and about 12cm (5in) in width. The colour of the plates vary from region to region; in the North Atlantic, it tends to be creamy white; in the North Pacific, it is usually creamy yellow; and in the Southern hemisphere it is creamy white at the front and dark grey at the back. Atlantic Minkes usually have more plates than the Pacific Minkes. Minke whales can be found virtually worldwide, but are less common in the tropics than in cooler waters. The Minke often enters estuaries, bays and inlets and during summer may feed around headlands and small islands. Most, seasonally migrating from polar feeding grounds to warm temperate to tropical breeding grounds although there appears to be some groups resident year-
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round. There are three geographically isolated populations recognised, in the North Pacific, in the North Atlantic and in the Southern Hemisphere. The Minke is the smallest of the seven great whales. It's size made it uneconomical to harvest commercially while the larger whales were in abundance. The species became protected with the declaration of the 'Moratorium' on whaling by the International Whaling Commission in 1986. Norway and Japan are two countries that argue since the Minke is abundant it is not endangered and therefore they are harvesting (killing), albiet in small numbers, this species on a regular basis. Although it's numbers are not endangered it is on the endangered list as a threatened species, and is protected (since 1986) worldwide by international law.
Suborder: Mysticeti Family: Balaenopteridae Subfamily: Balaenopterinae There may be two subspecies: Balaenoptera borealis borealis (Northern hemisphere) Balaenoptera borealis schlegelii (Southern hemisphere) Other Names: Pollack whale, Coalfish whale, Sardine whale, Japan Finner, Rudolphi's Rorqual The Sei Whale (Balaenoptera borealis) The Sei whale closely resembles the Bryde's whale in both size and appearance. From a distance it is almost impossible to tell them apart. This whale grows to a length of 12-17m (36-51ft) and weighs 20-30 tonnes. The Sei whale is called a "rorqual" a Norwegian word for "furrow" and refers to the pleated grooves running along its under-belly. These throat grooves, which extend from the lower jaw to the navel, in addition to streamlining the shape of the whale, allow the throat area (cavum vent-rale) to expand tremendously during feeding.
The head of the Sei whale forms up to a quarter of the total body length and compared with other rorquals is slender with a slightly arched forehead. It has twin blowholes with a low splashguard to the front. A single prominent longitudinal ridge along the top of the rostrum distinguishes the Sei whale from the Bryde's whale. The baleen plates in the mouth can be 75cm-80cm (30-32in) in length and number between 318-340 (Northern Hemisphere) and 300-410 (Southern Hemisphere).The baleen looks grey-black all over and fringed white near the tip of the snout. A Sei whale will feed mainly on copepods, though it also takes krill and other crustaceans. It will often skim the surface of the water with its mouth half open taking in food from patches of water concentrated with plankton. Sei whales also feed in the way most rorquals do, by openning its mouth widely to gulp in large quantities of water out of which it seives the tiny organisms. Most Sei whales live in the Southern Hemisphere while smaller populations inhabit the North Atlantic and North Pacific. There appears to be little or no mixing between the northern and southern populations. They are not normally found in extreme polar areas, although the subarctic and the subantarctic are favoured feeding grounds. They migrate from these polar and cold temperate feeding grounds to tropical to warm temperate breeding grounds. Sporadic annual invasions at specific locations are known as "Sei whale Years" but are not easy to predict. May be seen around islands but is rarely found close to shore elsewhere.
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Sei whales were heavily exploited by the whaling industry, especially during the 1960's and early 1970's and the population has been severely depleted. Estimates place the original number of Sei whales at 256,000 with current figures standing at 54,000 that's just 20% of natures intention. Now on the endangered list, the Sei whale is protected (since 1986) worldwide by international law. It is not to be hunted by anyone for any reason.
Suborder: Mysticeti Family: Balaenopteridae Subfamily: Megapterinae Other Names: Hump-backed Whale. The Humpback Whale (Megaptera novaeangliae) The Humpback whale is one of the most energetic of the rorquals. It is known for its spectacular breaching, flipper-slapping and lobtailing. It is easily identified at close range by its knobbly head and long flippers. The black and white colouration on the underside of the flukes (tail) allows scientists to distinguish and name individuals all around the world. No two Humpback whales are exactly alike. During breeding season the Humpback males are known for singing the longest and most complex songs in the animal kingdom. Humpbacks are highly inquisitive and will approach quite closely, showing little fear of boats. The Humpback whale has a more robust body than other rorqual. It's back and flanks are grey or black with an area of white on the throat and belly. It has a slender head which constitutes up to one-third of its total body length. The top of the head is flattened and covered by a number of fleshy knobs or tubercles. Unlike other rorquals the midline ridge on the top of the Humpback's head is indistinct. The lower jaw has a rounded protuberance near the tip and is covered with similar tubercles to those on the head. Baleen plates numbering between 270 to 400 are found on each side of the upper jaw. The plates are relatively short and black or dark grey.
The Humpback has exceptionally long flippers with knobs along the leading edges. While the underside of the flipper is usually white geographical differences have altered the upper side. On the flipper of Pacific Humpback the upper side is usually black whereas in populations of the Atlantic Humpback the upper side is mostly white with black markings. Humpback's have 14-35 broad throat groves which extend to the naval. The dorsal fin, placed nearly two thirds along the back, is variable in shape and size from a small triangular knob to a large distinctly sickle-shaped fin. The tail flukes are distinctly notched with trailing edges that are commonly scalloped (S-shaped) with knobs. The back is typically humped in front of the dorsal fin and the tail stock is relatively thin.
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The Humpback has twin blowholes typical of all baleen whales. It's blow appearing as a single bushy spout extending to 3m (10ft) in height. Humpback whales are wide ranging and can be found virtually worldwide, but with apparent geographical segregation between at least ten populations. Although some mixing does occur between these populations there has probably never been any contact between the Northern and Southern hemispheres. Humpbacks are strongly migratory, seasonally migrating from polar feeding grounds to warm temperate to tropical breeding grounds. Estimated at around 10,000 individuals worldwide the Humpback is an 'Endangered Species'. The healthiest populations occur in the western north Atlantic Ocean. A few other areas, include the waters near Beguia, Cape Verde, Greenland, and Tonga. Due to their tendency to aggregate on the tropical breeding grounds and to come close to the shore on the polar feeding grounds the Humpback whales were highly vulnerable to whalers. It is likely that more than 100,000 humpbacks were killed by whalers thoughout the modern whaling era and, although some stocks seem to be recovering, today's population is still a fraction of its original size. Humpback whales received protection in 1966 and again in 1985 when the International Whaling Commission instituted a moratorium on commercial whaling.
Suborder: Mysticeti Family: Eschrichtidae Other Names: California Gray Whale, Devilfish, Mussel-digger, Scrag Whale The Gray Whale (Eschrichtius robustus) The Gray Whale is one of the most active of all large whales with spyhopping, lobtailing and breaching commonly observed. The Gray can grow to a length and weight of 15m (50ft) 30-35 tonnes for the female and 14m (46ft) 16 tonnes for the male. This whale is well known for the 19,500km (12,000 mile) round trip between its northern feeding grounds in the Beaufort, Bering and Chukchi seas and its southern breeding grounds in Baja California and off the Korean coast.
The Gray whale is mottled grey over it's entire body including the flippers and tail flukes (though albino individuals are not uncommon). This grey body is covered with white, yellow or orange patches of barnacles and associated parasites (whale lice), particularly on top of the head, around the blowhole and on the anterior part of the back. The head is narrow and arched along the upper surface giving it a conical shape. It's mouth contains small hairs along the upper jaw with 130-180 relatively small baleen plates on each side. Primarily a bottom feeder, the Gray will dive to 120m (395ft) deep, but prefers much shallower water. While feeding it stirrs up clouds of mud from the seabed and from it's mouth during filtration. During this time the whale will mostly consume tubeworms and sessile polychaetes.
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While migrating the Gray will feed at the surface on small fish and shrimp-like mysids (Acanthomysis sculpta) but once the Arctic is reached it will consume it's main prey gammarid amphipods. Three populations once existed. One in the North Atlantic was hunted to extinction around 1700; a Korean population in the Northwest Pacific was hunted until 1968 and is now rare; the third, a Californian population in the Northeast Pacific still exists in moderate numbers, 17,000 - 18,000 despite earlier overexploitation. The Gray whale can be observed in December to April in Mexico, with small numbers in British Columbia, Canada, Washington State, Oregon,and northern California. The main breeding lagoons in Mexico are Ojo de Liebre, Guerrero Negro, San Ignacio, Scammon's and the Magdalena Bay complex. During April to November the whales inhabit their Arctic feeding grounds in the northern Bering Sea and southern Chukchi Sea.
Suborder: Mysticeti Family: Neobalaenidae Other Names: No other names Pygmy Right whale (Caperea marginata) The Pygmy Right whale is the smallest and least known of all the baleen whales. It has been rarely seen and most confirmed sightings have been limited to stranding reports from South Australia, Tasmania, New Zealand, South Africa and one from South America. This whale is similar in appearance to the Minke whale (Balaenoptera acutorostrata) but can be distinguished from it by its strongly arched jawline and the lack of Minke-like white flipper bands. Although the Pygmy Right whale shares the arched mouth with the larger Right whale (Eubalaena australis) the Pygmy has a dorsal fin, different flipper shape and a more streamlined body.
The head of this species is about 1/4 of its body size and the female is larger than the male. Their lengths range between 5 and 6.4 meters (16 to 21 feet) and they can weigh between 3 and 3.5 tonnes. As the Pygmy Right whale is a baleen whale it has no teeth. Its lower jaw is highly modified - bowed and slightly projecting beyond its strongly arched upper jaw. The line of the mouth extends behind and below the eye. Attached to the upper jaw, on each side, are 230 baleen plates pale grey or white in colour with dark outside edges. Although the tongue and the inside of the whale's mouth are white, often, when the mouth is open only the white band of the baleen gums can be seen. There are two indistinct longitudinal furrows on the throat. The Pygmy Right whale's back is grey or dark grey, with variable pale streaks extending to the shoulder and dark streaks from the eye to the flipper, lightening on the sides to white on the belly
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and lower jaw. The flanks and pectoral flippers are also grey or dark grey and contrast the lighter color of the sides. The flippers are small and narrow with slightly rounded tips. The dorsal fin is small, sickle-shaped and two-thirds along the back. The tail flukes are broad and distinctly notched. Although never seen feeding the Pygmy Right whale is believed to eat copepods. It is inconspicuous at sea and only surfaces for a few seconds at a time. It has not been observed breaching or lobtailing but it will throw its snout out of the water. Its flukes never lift clear of the water and sometimes its back and dorsal fin remain hidden for view. None of these whales have been found in the Northern Hemisphere. Distribution appears limited by the surface water temperature as they are almost always found in 5° to 20°C (41° to 68°F) temperature water. This excludes the whales presence south of the Antarctic Convergence and the cold waters of the Antarctic. Population numbers are unknown as it is easily confused with the Minke whale but Pygmy Right whales may be more common than the limited sightings suggest.
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Suborden Odontoceti Familia Delphinidae Subfamily: Globicephalinae Other Names: Orca, Great Killer Whale, Grampus. The (Orca) Killer Whale (Orcinus orca) The Killer whale is the largest member of the dolphin family. This distinctive jet-black, brilliant white and grey marked, huge dorsal finned male, makes this animal relatively easy to identify. The female and juvenile, at a distance however, can be confused with Risso's dolphin, the False Killer whale and even Dall's Porpoise. The Orca can grow to a length of 7m (23ft) and weigh 4-5,000 kg in the male and 6.6m (21ft) 2.5-3,000 kg in the female. Despite it's name, the Killer whale has never hurt a person in the wild. It is inquisitive and approachable and aggression within a pod is rare. The pod is a close-knit family group and is stable from one generation to the next. It's members usually stay together for life. When two or more pods come together temporarily the group is called a "superpod" and may number more than 150 whales. Usually larger groups split up into two or more smaller ones as the population grows. These groups of closely related pods (clans) often develop their own dialects. The head of the Killer whale is conical-shaped. It has an indistinct beak with a conspicuous white oval patch above and behind the eye. It's jaw is broad with relatively few large conical teeth, 10-12 pairs in each jaw, and very powerful muscles to the rear of the upper jaw. These aid the retainment of large prey that would normally resist capture. The Orca is a versitile predator and has one of the most varied diets of all whales. Although it has been observed feeding upon penguins, seals, porpoise and large baleen whales it's reputation for doing so is probably exaggerated. For most populations of Killer whales the diet appears to be primarily fish such as salmon and cod, and squid. It's consumption of birds, penguins, sea turtles, seals, and porpoise undoubtedly depends upon local availability.
More Killer whales live in cooler waters, especially polar regions, than tropical and subtropical regions. They are found in all seas including the Western Mediterranean, Arabian Sea and the Gulf of Aden. The largest population seems to be in Antarctica where it is estimated some 160,000 animals range. Sightings of Killer whales are usually restricted to within 800km (500 miles) of shore. Large concentrations are usually found over the continental shelf where they prefer deep water. Sightings
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within the surf zone although not as common include shallow bays, inland seas and estuaries but rarely in rivers. Although the Orca has no regular long migration ice cover attributes to it's local movement in high latitudes and food availability elsewhere. Studies suggest that Killer whales adopt one of two movement characteristics called "transients" or "residents". Transients tend to form smaller pods (1 to 7), roam over a wider area, feed predominantly on mammals, vocalise less frequntly, make abrupt changes in swimming direction, and often stay underwater for 5 to 15 minutes at a time. They also have a more pointed, centrally positioned dorsal fin than residents. Residents tend to form larger pods (5 to 25), have smaller home ranges, feed mainly on fish, vocalise frequently, keep to predictable routes, and rarely stay underwater for more than 4 minutes at a time. Regarded as too small by the commercial whalers the Killer whale population has not been depleted. While early whaling practices have accounted for Killer whale deaths and indeed many other small cetaceans, it is defined as 'subsistance' or 'aboriginal' whaling and refers to the catching of whales from small boats (or from the beach) to satisfy material and cultural needs in local communities. The indians of Vancouver and Washington on the Pacific coast of North America hunted the Gray whale and the Killer whale in this manner and for these reasons. Opportunistic hunting applies to modern whale catchers everywhere. With a fast boat and the right equipment its hard to pass up an easy kill so it is not uncommon for vessels from the Faroes catching Fin whales to harvest small species such as Killer whales and Atlantic White-sided Dolphin. Between 1938 and 1967 the Norwegians took 1,400 Killer whales in the Northeast Atlantic. During it's 1979-80 Southern Hemisphere whaling season the Soviet fleet targeted the Killer whale, with 916 killed, along with many larger species. A perceived conflict between man and whale in pursuit of a common source of food has led to many Killer whale deaths in the Icelandic and Norwegian herring fisheries.
Suborden Odontoceti Familia Delphinidae
Tucuxi Sotalia fluviatilis
Short-snouted Spinner Dolphin Stenella clymene
Long-snouted Spinner Dolphin Stenella longirostris
Atlantic Hump-backed Dolphin Sousa teuszii
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Pantropical Spotted Dolphin Stenella attenuata
Atlantic Spotted Dolphin Stenella frontalis
Southern Rightwhale Dolphin Lissodelphis peronii
Common Dolphin Delphinus delphis
Striped Dolphin Stenella coeruleoalba
Rough-toothed Dolphin Steno bredanensis
Indo-Pacific Hump-backed Dolphin Sousa chinensis
Northern Rightwhale Dolphin Lissodelphis borealis
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Bottlenose Dolphin Tursiops truncatus
Commerson’s Dolphin Cephalorhynchus commersonii
Hector’s Dolphin Cephalorhynchus hoctori
Heaviside’s Dolphin Cephalorhynchus heavisidii
Black Dolphin Cephalorhynchus eutropia
Hourglass Dolphin Lagenorhynchus cruciger
Dusky Dolphin Lagenorhynchus obscurus
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Peale's Dolphin Lagenorhynchus australis
Pacific White-sided Dolphin Lagenorhynchus obliquidens
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Atlantic White-sided Dolphin Lagenorhynchus acutus
Fraser's Dolphin Lagenodelphis hosei
Irrawaddy Dolphin Orcaella brevirostris
White-beaked Dolphin Lagenorhynchus albirostris
Risso's Dolphin Grampus griseus
Suborden Odontoceti Superfamilia Platanistoidea La superfamilia Platanistoidea está compuesta por cuatro géneros totalizando cuatro especies, una de ellas con dos subespecies
Familia
Género
Especie(binomial)
Subespecie
Nombres vulgares
Iniidae
Inia
Inia geoffrensis
Boto, Delfín del Amazonas
Lipotidae
Lipotes
Lipotes vexillifer
Baiji, Delfín chino de río
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Platanistidae
Pontoporiida e
Platanista
Pontopori a
P. gangetica gangetica
Delfín del Ganges
P. gangetica minor
Delfín del Indo
Platanista gangetica
Pontoporia blainvillei
Franciscana, Delfín del Plata
Suborden Odontoceti Familia Phocoenidae Phocoenidae es una familia de cetáceos constituida por las llamadas marsopas (lat = cerdos de mar ), que está relacionada con las ballenas y los delfines. Las marsopas incluyen a las especies más pequeñas del orden Cetacea, y el uso del término es confuso a nivel vernáculo, ya que suele llamarse marsopa a cualquier delfín de tamaño pequeño, aunque correspondan a una familia taxonómica diferente. La familia Phocoenidae está compuesta por 3 géneros totalizando seis especies y subespecies.
Género
Especie(binomial)
Subespecie
Nombres vulgares
Neophocaena
Neophocaena phocaenoides
Marsopa sin aleta
Phocoena phocoena
Marsopa común
Phocoena sinus
Vaquita marina o Cochito
Phocoena dioptrica
Marsopa de anteojos
Phocoena spinipinnis
Marsopa negra o espinosa
Phocoenoides dalli
Marsopa de Dall
Phocoena
Phocoenoide s
Diferencias entre marsopas y delfines • •
Tamaño: Las marsopas son más pequeñas, aunque comparativamente más robustas. Reproducción: las marsopas alcanzan la madurez sexual antes, y crían relativamente más vástagos que los delfines, poniendo el acento en la cantidad y no en calidad de la crianza, según los parámetros de la teoría biológica de selección r/K.
la
•
Dientes: las marsopas tienen dientes aplanados en lugar de la forma cónica de los delfines.
•
Aleta dorsal: las marsopas tienen una aleta caudal pequeña y triangular, e incluso no la presentan, como en la familia Neophocaena, mientras que los delfines presentan aletas de formas redondeadas.
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•
Hocico: redondeado en las marsopas, con los extremos de la boca levantados en lo que parece una eterna sonrisa. Los delfines suelen presentar en general un hocico aguzado en forma de pico.
Suborder: Odontoceti Superfamily: Physeteroidea Family: Physeteridae Other names: Cachalot, Great Sperm whale, Physeter catodon Food: Squid, octopus, fish - [N.Hemis.] rock fish, skate, angler fish, lumpsucker, cod, brown ragfish, [S.Hemis.] cusk eel, rough fish, groper, king-fish, eels. The Sperm Whale (Physeter macrocephalus) Although the Sperm whale is easily identified it rarely shows much of its body above the water. This whale has a very distinctive huge squarish head occupying at least one-third of its body and projecting, often up to 1.5m (5ft), well beyond its lower jaw. The large head contains a cavity called the spermaceti organ which is a mass of web-like tubes filled with a yellow wax. This organ is believed to be used in maintaining buoyancy and may also be used to focus sonar clicks. The Sperm whale has a robust body with corrugations in the skin giving it a shrivelled prune-like appearance. The skin is dark grey or brownish grey. It is paler at the front of the head and on the belly, with white fringes to the mouth particularly in the corners.
From the Suborder Odontoceti (toothed whale) the Sperm whale has in the lower jaw 20-25 large conical functional teeth (unpaired) in the male and fewer, smaller teeth in the female. The upper jaw has up to 10 frequently curved teeth in the male and none in the female. The teeth often erupt only at sexual maturity and then, in males, only in the lower jaw. The Sperm whale has one blowhole which gives a bushy blow projected forwards at a sharp angle to the left. There are two openings to the nasal passage divided by an external central septum but these are internal. The whale has no dorsal fin but it has a distinct triangular or rounded hump two-thirds along the body followed by a spinal ridge to broad triangular and deeply notched tail flukes. A thick 'keel' not seen in many whales runs along the underside of the tail stock. The Sperm whale is cosmopolitan in deep waters of all seas except close to ice edges. It is most common in submarine trenches at the edge of the continental shelf but may occur inshore where water is deeper than 200m (655ft). Migration to favoured areas for feeding and breeding may be undertaken however females undergo less extensive seasonal migration than males, usually only to 40°north and south of the Equator. Males regularly travel to 65°north and 70°south. Winter is spent in temperate and tropical waters. Some populations are resident year-round. Feeding areas include deeper waters around the Aleutian Islands in North Pacific, off New Zealand, Peru and Chile in the South Pacific, Newfoundland Grand Banks and the continental slope west of
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the British Isles, north towards Iceland in the North Atlantic, east coast of South America from Argentina to the Faulkland Islands and around Tristan da Cunha in the South Atlantic. Mating and calving areas include waters off New Guinea and around Hawaii in the North Pacific, deep waters off East Australia, Galapagos and Ecuador in the South Pacific, around the Bahamas, the Azores and Madeira in the North Atlantic, off Brazil, Angola and Southwest Africa in the South Atlantic, off Western Australia, around Madagascar, and west and north of Seychelles to the coasts of India, Sri Lanka and the Arabian peninsula in the Indian Ocean. The world population size has been reduced by whaling and the estimated curent number of Sperm whales is 1,900,000
Suborder: Odontoceti Superfamily: Physeteroidea Family: Kogiidae Other names: Lesser Cachalot, Lesser Sperm whale, Short-headed Sperm whale. Food: Squid, octopus, fish (deep-water), Decapod crustaceans. The Pygmy Sperm Whale (Kogia breviceps) Length: 2.7 - 3.4m (8 - 11ft) wt. 318 - 408 kg The Pygmy Sperm whale is often confused with the Dwarf Sperm whale with the two only distinguished apart at close range. It tends to live far from shore in deep waters and has inconspicuous habits. This whale tends not to approach boats and is most likely seen when resting. It will float motionless at the surface, with the upperside of its head and back above water and its tail hanging down limp in the water. When startled, the Pygmy Sperm whale may eject a redishbrown fluid before diving, leaving behind a dense cloud in the water. While this action is not fully understood it is believed that it may be a decoy like the ink of a squid. The Pygmy Sperm whale is dark blue-grey on the back, outer margin of the flippers and upper side of tail flukes, shading to pale grey on the flanks and dull white on the belly. Sometimes the belly has a pinkish tinge. The body is rather sharklike with a conical head which becomes more rectangular or squarish with age. A pale grey or white crescent shaped mark resembling the gill slits of a fish can be seen on the side of the head behind the eyes.
From the Suborder Odontoceti (toothed whale) the Pygmy Sperm whale has no functional teeth in the upper jaw but has 10-16 pairs of narrow inward-curved pointed teeth in the lower jaw. It has a tiny, underslung lower jaw. The Pygmy Sperm whale has one blowhole which gives a low and inconspicuous blow. The whale has a tiny, strongly sickle-shaped, falcate dorsal fin nearly two-thirds along its back and a tail with a concave trailing edge with a distinct notch between the tail flukes. Its flippers are broad but short and are located far forward on its body.
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The Pygmy Sperm whale is cosmopolitan in deep waters of most, if not all, temperate subtropical and tropical seas but it has not yet been recorded in the South Atlantic Ocean. Although poorly known through the lack of records of live animals it is known mainly from strandings. Records of beached Pygmy Sperm whales indicate that they are more common along the east coast of North America from Nova Scotia to Texas. Other areas include Peru, England, Holland, France, tip of South Africa, East Africa, Arabia, India, Sri Lanka, Southeast Australia, Tasman Sea, New Zealand, and the west coast of North America fro Washington to Baja California. The world population size is unknown but apparently it is not common. It is not know if the populations are isolated.
Suborder: Odontoceti Family: Ziphidae Other Names: Northern Giant Bottlenose Whale, North Pacific Bottlenose Whale, Giant Fourtoothed Whale, Northern Four-toothed Whale, North Pacific Four-toothed Whale. Baird's Beaked Whale (Berardius bairdii) Beaked whales are the least known of all cetaceans. Some have never been seen alive and have only been studied after dead animals were washed ashore. They may be rare or simply elusive but generally, they live in deep water far from land and have escaped live studies. Their most remarkable feature is the teeth. The teeth erupt in both males and females. In older animals they may be worn down to gum level. The front pair of teeth are exposed even when the mouth is closed and often appear brilliant white against the dark body when in bright sunlight. Baird's is probably the largest of all the beaked whales. It is similar in appearance to Arnoux's Beaked whale and some people say it is the same species. The two species are, however, geographically separated.
It has a long tube-like beak with a lower jaw protruding beyond the upper causing the front teeth to remain exposed when the mouth is closed. A second pair of teeth, smaller than the first, appear later in life but are concealed inside the mouth. The Baird's Beaked whale is slate-grey in colour and may appear darker or brownish at sea. It has a paler underside with white blotches on the throat, between the flippers and around the naval and anus. It has a long, elongated, spindle-shaped body which may be extensively scarred. The forehead is bulging and in the male it is more bulbous than the female. The dorsal fin is small, low and slightly rounded at the tip. The flukes, which are sometimes raised above the surface before a dive, have straight trailing edges and a slight notch in the middle. The flippers are small, slightly rounded and are placed far forward on the body. The blowhole is crescent shaped, backward pointing and on top of the head.
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Baird's populations are centered around the Aleutian Islands in the North Pacific, Sea of Okhorsk, California, Vancouver Island, Japan and the Emperor Seamounts northwest of Hawaii. These areas, however, may simply be a reflection of observer activity and may be seasonal peaks in these areas. Populations may occur inshore, but usually near or seaward of continental shelf, especially around submarine escarpments and seamounts. Small numbers of Baird's Beaked whales have been hunted off the Boso Peninsula, Japan, for several hundred years. Nowdays 40 to 60 animals are taken annually under a quota system.
Suborder: Odontoceti Family: Monodontidae Subfamily: Delphinapterinae Other Names: Belukha, Sea Canary, White whale Beluga Whale (Delphinapterus leucas) The Beluga whale has a very distinctive uniforn light colouration which changes with age. The male is larger than the female at a length of 3-5m (10-16ft) but this varies between populations. A Belugas weight is between 500-1,500kg. It is a slow swimmer and spends much of its time near the surface. They are prone to becoming trapped in ice making them easy prey for hunters and Polar bears. Body scars caused by unsuccessful bear attacks are fairly common in some pods. The adult Beluga is white but may appear yellowish at certain times of the year. The young are slate-grey to reddish-brown which changes to blue-grey at 2 years of age. Young animals may be similar in colour to Narwhals (Monodon monoceros) but are only found in the company of Beluga adults. The Beluga has a stout body with a small head and a short but distinct beak. Teeth are arranged in both the upper and lower jaws, 8-11 pairs of irregular often curved teeth in the upper jaw and 8-9 pairs in the lower jaw. It has a well-defined neck and a prominent rounded melon which may resonate during sound production. Like the Narwhal the Beluga has no dorsal fin. Instead, a Dorsal ridge extends along the back for about 50cm (20in) and may form a series of dark bumps. Both have unusually shaped flukes with convex trailing edges. They seem to face backwards in the Narwhal and although not as pronounced in the Beluga the trailing edges do become more convex with age. Flippers are broad, short, paddle-shaped and highly mobile. Much of the Beluga body, although evenly coloured, has a rough skin which may have creases and folds of fat. A well-defined crease can be found behind the single blowhole. The Beluga is one of the most vocal of the toothed whales. It has a large repertoire of clicks, moos, squeaks, trills and twitters which can be heard above and below the surface. By altering the shape of its forehead and lips a Beluga can make a variety of facial expressions. It may appear to smile, frown or whistle and while this may be a form of communication it is related to sound production. It may also have the most versatile and sophisticated sonar system of any cetacean. The Beluga is well adapted to living close to shore, it can swim in very shallow water and manoeuvre in depths barely covering its body. If stranded it can often survive until the next high tide. The Beluga feeds upon squid, fish and crustaceans. Occasionally, they will eat worms and molluscs by dislodging them from the bottom with the emission of a jet of water. A highly flexible neck aids in the scanning of the sea bottom and the capture of mobile prey.
Belugas are circumpolar, mainly Arctic but extending to subarctic, occupying coastal and estuarine areas. They are found off the coasts of Scandinavia, Greenland, Svalbard, the former Soviet Union,
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and North America. Many Belugas winter in areas of loose pack-ice where wind and ocean currents keep cracks and breathing holes open. Summers are spent in shallow bays and estuaries while some populations swim 1,000km (620miles) or more up river. Most populations do not make extensive migrations. The longest migration is by those that winter in the Bering Sea and summer in the Mackenzie River, Canada. Some make no migration at all, such as the residents of the St. Lawrence River, Canada. The total world population is unknown but is probably between 40,000 and 55,000. Most reside in Baffin Bay, Davis Strait, the Barents, Kara and Laptev Seas. The Beluga has been hunted by Arctic native people for hundreds of years but over-hunting by commercial operators during the 20th century has reduced their numbers. Present hunting rates are predicted to cause further population declines in Eastern Canada, Barents and White Seas.
Suborder: Odontoceti Family: Monodontidae Subfamily: Monodontinae Other Names: Narwhale The Narwhal (Monodon monoceros) The Narwhal is unlike any other cetacean. The male has a long spiralling tusk which is not normally possessed by the female. The tusk which grows to a length of 1.5-3m (5-10ft) is actually a modified tooth and looks like a twisted and gnarled walking stick. During the 17th century the Narwhal tusk was thought to have been the horn of the legendary unicorn. Studies suggest that males engage in aggressive behavior when competing for females. Scars attributed to tusk action have been found on the heads of adult males which are more likely to have broken tusks. The Narwhal shares many physical characteristics with the Beluga (Delphinapterus leucas). They are similar in shape and size, they have short beaks, rounded heads, lack dorsal fins and have a thick layer of blubber. An adult Narwhal will grow to a length of 4-5m (13-16ft) and weigh 0.8-1.6 tonnes. The head of the Narwhal is proportionately small with a bulbous forehead. While almost all males develope a single tusk from the tooth on the left-hand side of upper jaw, only 3% of females grow a thin tusk. All have a very slight beak, short flippers and flukes which appear to be on 'backwards'.
The Narwhal lives mainly in the High Arctic, often amongst the pack ice and generally offshore. There are large concentrations in the Davis Strait, around Baffin Bay and in the Greenland Sea. The advance and retreat of the ice initiates migration. The Narwhal is seldom found further south than 70 deg North and spends its summer in deep, cold fjords and bays. The Narwhal has a varied diet, feeding upon squid, fish and crustaceans. With few functional teeth this animal must use suction and the emission of a jet of water to dislodge prey such as bottomliving fish and molluscs. Its highly flexible neck aids the scanning of a broad area and the capture of more mobile prey.
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Although the Narwhal is preyed upon by Polar Bears, Walruses, Orcas and a number of sharks its major enemy is man. It has been hunted by the Inuit people for centuries for its tusk, flesh and other edible parts. Its thick skin is traditionally eated raw as a delicacy, much of the meat is fed to sled dogs and the blubber is rendered down for heating and lighting. In the Thule district Narwhal are still traditionally harpooned from kayak but most modern Inuit hunters use fast motor boats and high-powered rifles. Subsistance hunting communities have a long tradition of established rules but they clearly need to take account of developments that alter their operation from an 'aboriginal' manner. The world total for Narwhal's stands at between 25,000 and 45,000 animals.