Overview

Comprehensive Description

Species description

Longman's beaked whales, sometimes known as "tropical bottlenose" or "Indo-Pacific beaked whales," are one of the rarest and least known members of the beaked whale family (Ziphiidae). As adults, Longman's beaked whales can reach estimated lengths of about 20-30 ft (6-9 m); their weight is unknown. Compared to other beaked whales, this species is relatively large.

Longman's beaked whales have a large, robust body with a fairly large, "falcate" "dorsal" fin located far down their back. This species has dark, small, rounded, narrow flippers that fit into a depression on either side of the body. They have a well-defined "melon" (forehead) that is almost perpendicular to their long, tube-shaped beak. A crease may distinguish the melon from the beak. As they grow older, the melon develops into a steeper more bulbous shape that may hang over the beak. Like other beaked whales, they have V-shaped paired throat creases. As scientists have learned more about this species' external appearance and physical description, they have resolved confusion in various at sea sightings.

Longman's beaked whales have a relatively small, low, bushy blow that is usually visible and slightly angled forward. Longman's beaked whales generally have a darker grayish, bronze, brown, or olive coloration that extends from their blowhole and eye down their back, as well as a facial band. The melon and defined "thoracic" patch is lighter in color, sometimes described as "creamy" or pale. The upper jaw of the beak is darker and the lower jaw is lighter. The lower jaw has two conical shaped teeth located at the tip. Adult males have visible, erupted teeth (difficult to see in the field, especially when the mouth is closed), and may have linear and oval-shaped scars (e.g., bites from cookie-cutter sharks and lampreys) along their body.

Many species of beaked whales (especially those in the genus Mesoplodon) are very difficult to distinguish from one another (even when dead). At sea, they are challenging to observe and identify to the species level due to their cryptic, skittish behavior, a low profile, and a small, inconspicuous blow at the waters surface; therefore, much of the available characterization for beaked whales is to genus level only. Uncertainty regarding species identification of beaked whales often exists because of a lack of easily discernable or distinct physical characteristics.

Longman's beaked whales are usually found in tight groups averaging between 10-20 individuals, but occasionally have been seen in larger groups of up to 100 animals. They have sometimes been observed associating with other marine mammals such as pilot whales, spinner dolphins, and bottlenose dolphins. Dives may last from 14-33 minutes and their swimming style has been described as aggressive. This species is commonly misidentified when observed at sea.

The feeding behavior and prey of these cetaceans is generally unknown, but scientists believe it is similar to that of other beaked whales. Beaked whales are known to dive deep to forage for their food, possibly into the "sound channel." The analysis of stomach contents from one stranded specimen implies that cephalopods (e.g., squid and octopus) comprise the majority of the whale's diet.

Nothing is known about the reproduction or lifespan of this species. Due to the rarity, behavior, and infrequent encounters with this species, much of the information available is unreliable. A single young neonate calf was measured at 9.5 ft (2.9 m).

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Distribution

Specimens are recorded from Australia, Somalia, South Africa, the Maldives, Kenya, and Japan. From this information, the full range is currently thought to be the Eastern Pacific through the Indian Ocean to the eastern coast of Africa. Specimens have appeared rarely but widely throughout the Western Pacific and Indian Oceans. Until 2002, this species was only known by two skull specimens, recovered in 1926 and 1968. Flesh samples and live sightings have only been documented very recently.

Biogeographic Regions: indian ocean (Native ); pacific ocean (Native )

  • 2005. "Indopacetus pacificus (Longman's beaked whale)" (On-line). IBIS Seamap. Accessed October 14, 2005 at (http://seamap.env.duke.edu/species/tsn/180502).
  • Dalebout, M., G. Ross, C. Baker, R. Anderson, P. Best, V. Cockcroft, H. Hinsz, V. Peddemors, R. Pitman. 2003. Appearance, Distribution and Genetic Distinctiveness of Longman's Beaked Whale, Indopacetus Pacificus. Marine Mammal Science, 19/3: 421-462. Accessed November 14, 2005 at http://whitelab.biology.dal.ca/md/Indopacetus_2003.pdf.
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Range Description

There have been many sightings at widespread locations in the tropical Pacific and Indian Oceans (Dalebout et al. 2003). The distribution is not fully known, but it appears to be limited to the Indo-Pacific region (Culik 2004). The collected specimens are from Australia, Somalia, South Africa, the Maldives, Kenya, the Philippines, Taiwan and Japan. These beaked whales are relatively infrequently seen in the eastern tropical Pacific and may be more common in the western Pacific. They also appear to be more common in the western Indian Ocean, especially around the Maldives archipelago (Anderson et al. 2006).
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Offshore tropical and subtropical waters of the Pacific and Indian Oceans.
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Stranding Distribution

Distribution appears to be tropical waters of the Indian and South Pacific oceans.

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The distribution of Longman's beaked whales is poorly known and incomplete, but they are believed to occur in the tropical regions of the Indian and Pacific Oceans. In U.S. waters, this species has been sighted in the Hawaiian Exclusive Economic Zone (EEZ) and the equatorial tropical Pacific. Strandings (7 total events) have occurred on the coasts of East (Kenya and Somalia) and South Africa, northern Australia, the Maldives, the Philippines, South Japan, and Sri Lanka. Rare sightings have been documented in the eastern tropical Pacific Ocean. Sightings in the waters surrounding the Maldives archipelago and in the western Indian and Pacific Oceans are more frequent.

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Physical Description

Morphology

Size estimates range from 4 to 9 meters based on extrapolation from skull measurements. A Japanese specimen was 6.5 meters in length, which seems about average based on partial skeletal specimens. Like all beaked whales, this species has a prominent slender beak. Also diagnostic of beaked whales, the throat has two grooves which form a V shape and the fluke is not notched. This whale has a proportionately smaller head than most beaked whales. It is, however, larger overall than most of its close relatives. Longman’s beaked whales are most morphologically similar to Baird’s beaked whales (Beradius bairdii). They may be distinguished, however, because Longman’s beaked whales have a blow hole with concavity oriented forward, toward the anterior of the whale. In Baird’s whales the blow hole tilts toward the posterior. The dorsal fin is larger than that of most beaked whales. The lower jaw contains only a pair of oval teeth, which do not protrude from the jaw. The skin coloration varies between brown and bluish gray and tends to lighten around the flank and head. These whales are sexually dimorphic, with males tending to be larger. Weight estimates could not be found.

Range length: 4 to 9 m.

Sexual Dimorphism: male larger

Other Physical Features: endothermic ; bilateral symmetry

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Skull morphology

Diagnostic features of the skull and mandible

On the vertex of the dorsal skull the premaxillary bone extends forward of the nasal and frontal bones. Separates from Berardius and Ziphius.

No sulcus exists in middle if the combined antero-dorsal surface of the nasals. Separates from Mesoplodon and Hyperoodon.

Frontal bones occupy an area of the vertex of the skull approximating or exceeding that occupied by the nasal bones. Separates from Berardius, Ziphius, Tasmacetus, and Hyperoodon.

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External Morphology

Head Shape

Similar in appearance to Hyperoodon. The medium length beak is distinct from the bulbous forehead. The melon meets the rostrum at an angle of 75 degrees rather than the more severe 90 degrees as seen in Hyperoodon. The mouthline is weakly sinusoidal.

Coloration

The following description is based on neonate and juvenile color pattern, adult coloration may vary. Posterior to the blowhole, the entire dorsal surface is black, becoming dark gray laterally prior to merging smoothly with the white ventral surface. Posterior to the eye on the lateral surface, the black of the dorsum extends ventrally in a broad band towards the anterior insertion of the flipper, becoming gray at the insertion. A dark band of black extends ventrally from the blowhole to join a black patch surrounding the eye. A small lighter patch is embedded in the area of dark pigmentation posterior to the eye.

Size

Body length range of adult animals is unknown. Recorded maximum body length for an adult female is 5.6 m. Mean body length at birth is unknown.

Most Likely Confused With:

Berardius arnuxii

Hyperoodon planifrons

Tasmacetus shepherdi

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Ecology

Habitat

Longman’s beaked whales are pelagic and feed in the deep sea. This conclusion is based on the extreme rarity of sightings and the lifestyles of related species. Also, a specimen was discovered off the coast of Japan in July of 2002. This specimen had distinctive bites from a cookie cutter shark (Isistius brasiliensis). This shark generally lives in the deep sea and its bites are common in deep sea marine life. There is very little data for any of the species in the family Ziphiidae, but one study found that the maximum depth for this related species was 1267 meters.

Habitat Regions: tropical ; saltwater or marine

Aquatic Biomes: pelagic

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Habitat and Ecology

Habitat and Ecology
The sightings of this species come from scattered locations, many in deep, oceanic waters, in the tropical to subtropical Indo-Pacific. Sightings have occurred in areas with surface water temperatures of 21-31°C.

Nothing is known of its feeding habits, except for the stomach contents of a single specimen from Japan (Yamada 2003). These suggested that the species feeds primarily on cephalopods, like other beaked whales.

Systems
  • Marine
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tropical to warm temperate
  • UNESCO-IOC Register of Marine Organisms
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Depth range based on 5 specimens in 1 taxon.
Water temperature and chemistry ranges based on 5 samples.

Environmental ranges
  Depth range (m): 0 - 0
  Temperature range (°C): 25.484 - 28.736
  Nitrate (umol/L): 0.050 - 3.535
  Salinity (PPS): 33.182 - 34.984
  Oxygen (ml/l): 4.613 - 4.716
  Phosphate (umol/l): 0.167 - 0.522
  Silicate (umol/l): 1.970 - 3.914

Graphical representation

Temperature range (°C): 25.484 - 28.736

Nitrate (umol/L): 0.050 - 3.535

Salinity (PPS): 33.182 - 34.984

Oxygen (ml/l): 4.613 - 4.716

Phosphate (umol/l): 0.167 - 0.522

Silicate (umol/l): 1.970 - 3.914
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Longman's beaked whales live in generally warm (69.8-87.8° F, 21-31° C), deep (greater than 3,300 ft (1,000 m)), "pelagic" waters of tropical and subtropical regions.

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Trophic Strategy

The Japanese specimen’s stomach contents were analyzed, and revealed the beaks of cephalopods.

Animal Foods: mollusks

Primary Diet: carnivore (Molluscivore )

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Associations

The stomach contents of a Japanese specimen revealed parasitic nematodes. Specifically, Anisakis individuals were extracted. These roundworms are known to parasitize cetaceans.

Ecosystem Impact: creates habitat

Commensal/Parasitic Species:

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Based on the distinctive bites visible on the Japanese specimen, cookie cutter sharks (Isistius brasiliensis) may feed on Longman’s beaked whales. Their large size makes them unlikely prey.

Known Predators:

  • Baird, R., P. Clapham, J. Christal, R. Connor, J. Mann, A. Read, R. Reeves, A. Samuels, P. Tyack, L. Weilgart, H. Whitehead, R. Wells, R. Wrangham. 2000. Cetacean Societies. Chicago: University of Chicago Press.
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Life History and Behavior

Behavior

Pelagic beaked whales use echolocation to locate food.

Communication Channels: acoustic

Perception Channels: tactile ; echolocation ; chemical

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Life Expectancy

Natural lifespan of this species is unknown; it has never been kept in captivity.

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Reproduction

No information is available on the mating system in this species.

No information is available on reproduction in Longman's beaked whales. In fact, very little information is known about beaked whale (Ziphiidae) reproduction in general. Most toothed whales (Odontoceti), the mammalian suborder that includes beaked whales, have a gestation period of ten to twelve months. Lactation may last from 18 to 24 months, or more. Calving generally occurs every two or three years, and some females may become pregnant while still lactating. Males tend to be larger and reach sexual maturity later.

Breeding interval: There is no information on breeding interval.

Breeding season: There is no information on breeding season in Longman's beaked whales.

Key Reproductive Features: iteroparous ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous

Like all placental mammals (Eutheria), female beaked whales gestate young for an extended period, and protect and nourish them until they reach independence. Some whales travel in family groups and maintain bonds after young have reached independence. No specific information is available for Longman's beaked whales.

Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)

  • Evans, P. 1987. The Natural History of Whales & Dolphins. New York: Facts On File.
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Molecular Biology and Genetics

Molecular Biology

Tooth morphology

Tooth position

A single pair of teeth is located at the apex of the lower jaw. These incline forward at 45 degrees. These teeth are conical, incline forward at 45 degrees, and do not erupt above the gumline in adult females or juveniles. Female teeth were oval in cross section at their base. Though no adult male specimens have been described it is likely the teeth erupt beyond the gumline and are also oval in cross section.

Tooth exposure

These teeth do not erupt above the gumline in adult females or juveniles.Though no adult male specimens have been described it is likely the teeth erupt beyond the gumline.

Tooth shape

Teeth are conical and oval in cross section.

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Conservation

Conservation Status

There is very little information on Longman's beaked whales, they are considered data deficient by the IUCN and are not listed by CITES or the U.S. Endangered Species Act.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: data deficient

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IUCN Red List Assessment


Red List Category
DD
Data Deficient

Red List Criteria

Version
3.1

Year Assessed
2008

Assessor/s
Taylor, B.L., Baird, R., Barlow, J., Dawson, S.M., Ford, J., Mead, J.G., Notarbartolo di Sciara, G., Wade, P. & Pitman, R.L.

Reviewer/s
Hammond, P.S. & Perrin, W.F. (Cetacean Red List Authority)

Contributor/s

Justification
There is almost no information on abundance and no information on trends in global abundance for this species. As a relatively uncommon species it is potentially vulnerable to low-level threats and a 30% global reduction over three generations cannot not be ruled out.

History
  • 1996
    Data Deficient
    (Baillie and Groombridge 1996)
  • 1996
    Data Deficient
  • 1996
    Data Deficient
  • 1994
    Insufficiently Known
    (Groombridge 1994)
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Population

Population
While it is certainly not the rarest of beaked whales, the paucity of recent sightings of Longman’s beaked whales indicate that it is not particularly common either. The only estimates of abundance available are of 1,007 individuals (CV=126%) in the waters around Hawaii (Barlow 2006), and 291 (CV=100%) in the eastern North Pacific (Ferguson and Barlow 2001).

There is no information on trends in the global abundance of this species.

Population Trend
Unknown
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Population Trends

For management purposes, Longman's beaked whales inhabiting U.S. waters have been placed into a single Hawaiian stock. The population of Longman's beaked whales is unknown and no estimates exist. Based on a shipboard line-transect survey from 2002, the best available abundance estimate for the stock that occurs throughout the Hawaiian Islands "EEZ" is 370-770 individuals. There are insufficient data available on current population trends.

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Threats

Major Threats
Direct hunting has never been associated with this species. Pervasive gillnet and longline fisheries throughout the species' range raises concern that some bycatch is likely. Even low levels of bycatch might cause unsustainable impacts on this naturally rare cetacean.

It is unknown if military, seismic or other loud noise-producing human activities resulted in the live stranding of a possible mother/calf pair in NE Taiwan (Wang and Yang 2006; Yang et al. 2008). However, “bubble-like lesions” were reported in at least one of these whales by Yang et al (2008). There is some evidence from Sri Lanka for occasional incidental or directed takes of animals identified as ‘bottlenose whales’ which are likely to be Indopacetus (Dayaratne and Joseph 1993).

Evidence from stranded individuals of several similar species of beaked whales indicates that they have swallowed discarded plastic items, which may eventually lead to death (e.g. Scott et al. 2001); this species may also be at risk.

This species, like other beaked whales, is likely to be vulnerable to loud anthropogenic sounds, such as those generated by navy sonar and seismic exploration (Cox et al. 2006).

Predicted impacts of global climate change on the marine environment may affect this species of whale, although the nature of impacts is unclear (Learmonth et al. 2006).
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There are no known incidents or reports of this species being exploited by humans such as direct hunting. However, they have been recorded as bycatch in fisheries operating in Sri Lanka. Additionally, various types of fishing gear pose a risk of entangling or interacting with this species. This species of beaked whales may be sensitive to underwater sounds and anthropogenic noise. Anthropogenic noise levels in the world's oceans are an increasing habitat concern, particularly for deep-diving cetaceans like Longman's beaked whales that use sound to feed, communicate, and navigate in the ocean.

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Management

Conservation Actions

Conservation Actions
The species is listed in Appendix II of CITES. Research is needed to determine the impact of possible threats on this species.
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Relevance to Humans and Ecosystems

Benefits

It is unlikely that beaked whales have negative impacts on humans.

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Longman's beaked whales are important members of healthy ocean ecosystems.

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Risks

IUCN Red List Category

Data Deficient (DD)
  • IUCN (2008) Cetacean update of the 2008 IUCN Red List of Threatened Species.
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Wikipedia

Tropical bottlenose whale

Tropical bottlenose whale!<-- This template has to be "warmed up" before it can be used, for some reason -->

The Tropical Bottlenose Whale (Indopacetus pacificus), also known as the Indo-Pacific Beaked Whale and the Longman's Beaked Whale, was considered to be the world's rarest cetacean until recently, but the Spade-toothed Whale now holds that position. The species has had a long history riddled with misidentifications, which are now mostly resolved. A skull found in Mackay, Queensland, Australia provided the initial description, but some authorities insisted on classifying it was a True's Beaked Whale or a female Bottlenose Whale instead of a new species. A whale washed up near Danae, Somalia in 1955 was processed into fertilizer with only the skull remaining, and biologist Joseph C. Moore used it to effectively demonstrate that it was a unique species. However, there was a considerable debate as to whether the whale belonged in the genus Mesoplodon or not. The next major development happened when a paper, available here, had shown that there were actually six remains of the whale, including a complete female with a fetus found in the Maldives in 2000. The other remains consisted of a skull from Kenya from before 1968, and two juveniles from South Africa in 1976 and 1992 respectively. The paper used DNA analysis to show that the Tropical Bottlenose Whale is likely to be an independent genus, but information on other species was too lacking to establish any concrete phylogeny. The external physical appearance was also revealed, and a firm connection was established with the mysterious Tropical Bottlenose Whales sighted in the Indian and Pacific Oceans. During the publication of the paper, a specimen originally identified as a Giant Beaked Whale washed up in Kagoshima, Japan in July 2002. Another specimen claimed to be a Tropical Bottlenose Whale which washed up in South Africa in August 2002 is likely a misidentified Cuvier's Beaked Whale.

Contents

Physical description

The Longman's Beaked Whales look rather similar to both Mesoplodont Beaked Whales and Bottlenose Whales, which led to a great deal of taxonomic confusion. The Maldives female had a robust body like the Bottlenose Whales, although this may be a distortion since the less decomposed female specimen from Japan had a laterally compressed body typical of Mesoplodonts. The juvenile specimens have a very short beak similar to a Bottlenose Whale, but the adult females seen so far have had rather long beaks sloping gently into a barely noticeable melon organ. Additionally, the dorsal fins of adult specimens seem unusually large and triangular for Beaked Whales, whereas in juveniles they are rather small and swept back. An adult male specimen has yet to wash up, but sightings of the Tropical Bottlenose Whale indicate that they have a rather bulbous melon, two teeth located towards the front of the beak, as well as the scars from fighting with the teeth. Scars from cookiecutter sharks are also rather common on the whale. The rather unusual coloration of the juveniles helped connect the Longman's Beaked Whale to the Tropical Bottlenose Whale; both of them have a dark back behind the blowhole which quickly shades down to a light gray and then white. The blackness from the back extends down to the eye of the whale except for a light spot behind the eye, and then continues on in a line towards the flipper, which is also dark. Dark markings are also present on the tip of the beak and rostrum. The females have a simpler coloration; the body is typically grayish except for a brown head. It appears that the coloration is rather variable in this species. The female specimen from the Maldives was 6 meters (20 feet) in length with a 1 meter (3 foot) fetus, and the Japanese female was 6.5 meters (22 feet) in length. Reports of Tropical Beaked Whales put them at even larger length in the 7-8 meter (23–26 foot) range, which is larger than any Mesoplodon and more typical of a Bottlenose Whale. No weight estimation or reproductive data is known.

Population and distribution

Carcasses indicate the species ranges across the Indian Ocean from Southern and Western Africa to the Maldives, with a Pacific range extending from Australia up to Japan. However, if the sightings of the Tropical Beaked Whale are taken into account, the range of this whale is extensively larger. They have been sighted from the Arabian Sea to the western shore of Mexico. They have also been seen in the Gulf of Mexico, which would indicate that they are present in the tropical Atlantic Ocean as well. The most frequent observations have occurred off the coasts of Hawaii. While no specimens have washed up from Hawaii, they are apparently rather common; a 2002 survey estimates that there were 766 animals. No other population estimates exist for other locales.

Behavior

Tropical Bottlenose Whale observations indicate that they travel in larger groups than any other local species of beaked whale. The size of the pods range from the tens up to 100, with 15 to 20 being fairly typical, and the groups appear very cohesive. Their pods are frequently associated with other species, such as Short-finned Pilot Whales and Bottlenose Dolphins. Tropical Bottlenose Whales have been known to breach the surface, and they normally have visible, but short, blows. Their dives have been clocked at 18 to 25 minutes.

Conservation

There are no records of the whale being hunted, caught in fishing gear, or affected by Navy Sonar. Due to their rather uncommon nature, their conservation status is unknown.

Sources

  • Longman's Beaked Whale Hawaiian Stock. Revised 3/15/05. Available: here
  • Appearance, Distribution, and Genetic Distinctiveness of Longman's Beaked Whale, Indopacetus pacificus. Dalebout, Ross, Baker, Anderson, Best, Cockcroft, Hinsz, Peddemors, and Pitman. July 2003, Marine Mammal Science, 19(3):421–461. Available: here
  • National Audubon Society Guide to Marine Mammals of the World Reeves et al., 2002. ISBN 0-375-41141-0.
  • Sightings and possible identification of a bottlenose whale in the tropical Indo-Pacific: Indopacetus pacificus? Pitman, Palacios, Brennan, Brennan, Balcomb and Miyashita, 1999. Marine Mammology Science Vol 15, pps 531-549.
  • Encyclopedia of Marine Mammals Robert L. Pitman, 1998. ISBN 0-12-551340-2
  • Whales, Dolphins and Porpoises Carwardine, 1995. ISBN 0-7513-2781-6
  • More skull characters of the beaked whale Indopacetus pacificus and comparative measurements of austral relatives J.C. Moore 1972. Field Zoology. Vol 62 pps 1-19.
  • Relationships among the living genera of beaked whales with classifications, diagnoses and keys J.C. Moore 1968. Field Zoology. Vol 53, pps 206-298.

References

  1. ^ Taylor, B.L., Baird, R., Barlow, J., Dawson, S.M., Ford, J., Mead, J.G., Notarbartolo di Sciara, G., Wade, P. & Pitman, R.L. (2008). Indopacetus pacificus. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 24 March 2009. Database entry includes a brief justification of why this species is of data deficient.
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Notes

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· Longman's beaked whales are one of the rarest cetaceans. Until fairly recently, this species was only known and described from two skulls found on beaches in Africa (in 1955) and Australia (in 1882, but described by Longman in 1926).

· Longman's beaked whales were originally placed in the Mesoplodon genus (given the name Mesoplodon pacificus in 1926), but due to differences in features of the skull they have been reclassified as their own genus, Indopacetus.

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