Overview

Distribution

The general distribution of Gray's beaked whales, Mesoplodon grayi , is in the oceans of the southern hemisphere, south of 30 degrees latitude. Original sightings were off the coast of New Zealand and Eastern Australia east to Argentina and Chile. However, recent sightings near South Africa, north to Madagascar, and in the Indian Ocean east to Australia confirm its circumpolar home range. There has been one confirmed live animal sighting in the northern hemisphere, off the coast of The Netherlands, but there have been no other indications of a North Atlantic population (IUCN, 1991).  Though there are nineteen species in the Family Ziphiidae (Beaked Whales), they are rarely seen and poorly studied. There is no reliable information on migratory habits, if any, of this species.

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

  • Evans, P. 1987. The Natural History of Whales & Dolphins. New York, New York USA: Facts on File, Inc.
  • Klinowska, M., J. Cooke. 1991. Dolphins, Porpoises, and Whales of the World. Switzerland and Cambridge, U.K.: IUCN The World Conservation Union.
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Physical Description

Morphology

Gray’s Beaked whales, like all members of Ziphiidae, are medium sized whales with a distinct beak. They are 5.0 to 6.0 m in length and weigh around 5 tons (10,000 pounds). M. grayi is distinct from all other beaked whales (except for Tasmacetus shepherdi) in that it does not lack upper teeth; rather, it has a row of 17 to 22 teeth lining each side of the upper jaw.

The coloration pattern of M. grayi is similar to other beaked whales, with dark brown to gray on the back and flanks, and light gray to white on the underside. The beak is characteristically white or light colored with white flecks extending to the throat. There are also conspicuous white markings around the navel, genitals, and anal regions.

One of the most conspicuous features of members of the genus Mesoplodon is the single pair of enlarged triangular tusks in the lower jaw. The location of these tusks is set farther back in the mouth than in other beaked whales. The exact function of these tusks is unknown, but the pattern of scarring on the head and body of examined individuals indicates that fighting may occur, most likely for mates . Some Mesoplodon have a hardened bone in their skulls, acting like a shield while fighting. These tusks were originally thought to erupt only in males. However, more recent information shows that the tusks erupt in both sexes. Beached females with erupting tusks, have been discovered recently with high frequency.

Average mass: 5000 kg.

Range length: 5.5 to 6.0 m.

Sexual Dimorphism: sexes alike; ornamentation

Other Physical Features: endothermic ; bilateral symmetry

  • MacLeod, C. 2000. Species recognition as a possible function for variations in position and shape of the sexually dimorphic tusks of Mesoplodon whales. Evolution, 56/6: 2171-2173.
  • MacLeod, C. 2002. Possible functions of the ultradense bone in the rostrum of Blainville's beaked whale (Mesoplodon densirostris). Canadian Journal of Zoology, 80:1: 178-184.
  • Culik, B. 2002. "Mesoplodon grayi" (On-line). Convention on Migratory Species (CMS). Accessed August 08, 2004 at http://www.cms.int/reports/small_cetaceans/data/m_grayi/m_grayi.htm.
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Tooth morphology

Tooth position

A single pair of large teeth are positioned back from the apex at 50 - 60% of total length of the mouthline. The tooth root is squared at its base and the teeth have a slight anterior incline or no incline at all. This is the only mesoplodont to have maxillary teeth. Up to 17-22 regularly spaced maxillary teeth begin at the same position along the jaw as the single pair of teeth in the lower jaw. There are no alveoli and they protrude only a few millimeters external to the gum.

Tooth exposure

Erupted teeth of adult males are covered in gum tissue with only the tips of the teeth exposed. Teeth in females and juveniles do not erupt.

Tooth shape

Anterior and posterior tooth margins are sinusoidal with the tooth apex slightly offset from the midline of the tooth.

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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.

A sulcus (groove) running along the middle of the combined surfaces of the nasal bones so depresses their combined middle that it is the lateral portion of each nasal bone that reaches farthest forward on the vertex. Separates from Tasmacetus and Indopacetus.

When the skull is upright and the long axis of the anterior half of the beak is horizontal, a horizontal plane transecting the summit of either maxillary prominence transects the mesethmoid bone. Separates from Hyperoodon.

Tooth alveoli of mandible are positioned b etween apex and posterior mandibular symphysis.Separates from Berardius, Ziphius, Tasmacetus,Indopacetus, Hyperoodon, M. bowdoini, M. carlhubbsi, M, ginkgodens, M. hectori, M. layardii, M. mirus, M. perrini, M. densirostris, M. peruvianus, M. stejnegeri, and M. traversii.

Deep basirostral groove extends anteriorly well past the prominental turbercle. Separates from M. bidens and M. europaeus.

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External morphology



Head Shape

The melon may bulge slightly or not at all in front of the blowhole and slopes smoothly to the long and pointed beak. The mouthline is relatively straight.

Coloration

Adult males are darkly pigmented over entire body except for the rostrum and lower jaw which are white. Females are dark gray on the dorsal surface and light gray on the ventral surface, with patches of white around the umbilical scar, genital and anal slit and mammary slits. The lower jaw and upper lips are light gray. The flippers are darker than the surrounding body.

Size

Adult body length ranges between 5.3 to 5.8 m. Recorded maximum body length for adult males and females is 5.6 m and 5.8 m, respectively. Length at birth is 2.4 m.

Most Likely Confused With:

Mesoplodon layardii

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Ecology

Habitat

The particular waters M. grayi occupies are not well known. Animals are generally spotted in waters deeper than 2000 m, but animals frequent shallower waters and have often been found beached in New Zealand.

Range depth: 2000 to 0 m.

Habitat Regions: temperate ; tropical ; saltwater or marine

Aquatic Biomes: pelagic ; coastal

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Depth range based on 674 specimens in 11 taxa.
Water temperature and chemistry ranges based on 656 samples.

Environmental ranges
  Depth range (m): 0 - 0
  Temperature range (°C): -1.670 - 29.038
  Nitrate (umol/L): 0.026 - 27.643
  Salinity (PPS): 31.430 - 36.478
  Oxygen (ml/l): 4.582 - 8.094
  Phosphate (umol/l): 0.055 - 1.846
  Silicate (umol/l): 0.824 - 66.028

Graphical representation

Temperature range (°C): -1.670 - 29.038

Nitrate (umol/L): 0.026 - 27.643

Salinity (PPS): 31.430 - 36.478

Oxygen (ml/l): 4.582 - 8.094

Phosphate (umol/l): 0.055 - 1.846

Silicate (umol/l): 0.824 - 66.028
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Trophic Strategy

Beaked whales of the genus Mesoplodon eat squid almost exclusively, usually members of the families Ommastrephidae, Octopoteuthidae, Enoploteuthidae, and Neoteuthidae. Mesoplodon may also feed on deep-sea and mesopelagic fish (Lampanyctus, Scopelogadus, Cepola), but they are likely to be only opportunistic prey; squid make up the great majority of the diet.

Animal Foods: fish; mollusks

Primary Diet: carnivore (Molluscivore )

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Associations

The evolutionary development of dentition in mesoplodont whales and their nearly exclusive diet of squid, indicate that there must be a strong ecological relationship between these organisms. The highly specialized tongue and reduced teeth allow the whales to use suction to capture their prey. The stomach remains of mesoplodont whales almost always contains squid species smaller than 500 g, which contrasts sharply with other beaked whales (genera Hyperoodon and Ziphius) whose diet consists mainly of squid averaging 1000 g in weight (CMS, 2003). This information indicates that Mesoplodon occupies a dietary niche separate from other beaked whales.  The preference for and effectiveness at capturing squid suggests that mesoplodont whales strongly impact the squid population.

Species Used as Host:

  • Data Unknown

Mutualist Species:

  • Data Unknown

Commensal/Parasitic Species:

  • Data Unknown

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Natural preadators of Gray's Beaked whales are unknown. The natural coloration pattern (dark on the dorsal side, lighter on the belly) makes these animals harder to see from above (where they blend in with darker water below) and from below (where they blend in with lighter water above it).

This species is not known to be commercially hunted, but the possibilty that individuals have been taken by fishing operations cannot be excluded. However, the known population of M. grayi generally resides outside of most commercial fishing operations and the impact of these operations is probably limited.

Anti-predator Adaptations: cryptic

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Life History and Behavior

Behavior

The communication habits of M. grayi are unknown, but those of other whales have been well studied. Whales are famous for their combination of songs, squeals, grunts, clicks, and clacks. Because water serves as a much better transmission medium for sound than air, evolution has clearly centered on vocal communication rather than any other form. The timing of whale communications, along with their content, may signal position, identity, threats, or food to other members of a pod or to other pods.

The most common beaked whales, Blainville's Beaked whales, have been observed to use particular patterns of clicks when herding schools of prey, possibly to confuse them. It has been proposed that M. grayi uses similar methods, but further information is unavailable.

Some tactile communication most likely occurs between mates, as well as between mothers and their offspring. If the tusks of these animals are used in physical competition, as scarring patterns on the head indicate, this is another form of tactile communication which should be noted.

Females may signal their sexual readiness with chemical cues.

Communication Channels: tactile ; acoustic ; chemical

Other Communication Modes: choruses

Perception Channels: visual ; tactile ; acoustic ; chemical

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Life Expectancy

There is no information on the lifespan of M. grayi and there have been no reports of attempts to keep any animals in captivity.

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Reproduction

Unfortunately, there is little information on the mating system of M. grayi. However, it is very likely that M. grayi follows similar patterns to other toothed whales (Odontoceti). M. grayi, like other toothed whales, does not show as distinct a seasonality in mating and birth as do the baleen whales; this is primarily due to the relatively warmer waters the toothed whales inhabit. Toothed whales live in small groups with very large ranges of thousands of square miles. It may be difficult for individuals to meet others of the opposite sex, so when they do, it is essential that the right signals are conveyed. Toothed whales are very social, and when pods meet there are physical changes in the female’s body to indicate to potential mates that she is ready. Though these exact signals are unknown, it is likely that a combination of both behavioral dance-like movements and hormones discharged through feces or urine serve as cues.

The courtship and mating rituals usually involve belly contact between the male and female. The pair may be interlocked vertically, or the male may swim upside-down underneath the female. There is also much play in the form of chases, breaching of the surface, and flipper contact. All these behavioral cues convey the readiness to mate.

Detailed information on the reproductive behavior of M. grayi is unavailable. The mother most likely give birth to a single calf. Gray’s beaked whales, like many whales, are most often seen in pods and highly social behavior has been observed. Often in these groups, females that don't have offspring of their own assist other females in the pod raise their calves. A calf likely remains by its mother’s side until it reaches maturity.

Although toothed whales occupying warm oceanic waters can breed throught the year, most breeding in the southern hemisphere is probably between October and December, and the young are born between February and March. Breeding grounds for similar species are often in shallower waters that are sheltered by bays or inlets. Seasonal movements from winter mating grounds to summer feeding grounds are common for other species but not confirmed for M. grayi.

Breeding interval: Unknown; Probably one calf per year.

Breeding season: Unknown; Probably between October and December

Average number of offspring: 1.

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

All cetacean species follow a similar pattern for parental investment. The mother nurses the young; she and the pod family teach newborn calves how to socialize, how to avoid preadators, and how to hunt. Specific information on M. grayi is unavailable.

Parental Investment: no parental involvement; precocial ; female parental care ; pre-fertilization (Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Protecting: Female); extended period of juvenile learning

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

Molecular Biology

Statistics of barcoding coverage

Barcode of Life Data Systems (BOLD) Stats
Specimen Records: 23
Specimens with Sequences: 17
Specimens with Barcodes: 17
Species: 4
Species With Barcodes: 2
Public Records: 17
Public Species: 2
Public BINs: 7
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Barcode data

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Conservation

Conservation Status

M. grayi is protected by the Marine Mammal Protection Act of 1972. These laws are a strict guideline protecting marine mammals and their habitats. For M. grayi in particular, there is not enough information to determine its appropriate conservation status. Original sightings were so rare that the animals were thought to be close to extinction, but the increasing number of reliable sightings suggests there is a larger, more stable population than believed.

IUCN Red List of Threatened Species: no special status

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Relevance to Humans and Ecosystems

Benefits

There are no known adverse affects of M. grayi on humans.

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The instances of humans encountering M. grayi are so rare that it probably has little direct economic importance. Further information is unavailable.

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Wikipedia

Gray's beaked whale

Gray's beaked whale!<-- This template has to be "warmed up" before it can be used, for some reason -->

Gray's Beaked Whale (Mesoplodon grayi), sometimes known as Haast's Beaked Whale, the Scamperdown Whale, or the Southern beaked whale, is one of the better-known members of the genus Mesoplodon. The scientific name refers to John Edward Gray, a zoologist at the British Museum. This species is fairly gregarious and strands relatively frequently for a beaked whale. It is notable for being the only beaked whale, other than Shepherd's Beaked Whale (not a Mesoplodon), that has numerous teeth.

Contents

Description

Gray's Beaked Whale is a fairly slender member of the genus. The melon on the whale bulges towards the blowhole and slopes down towards the beak. The beak itself is very long and pointed for a beaked whale, and has a relatively straight mouth line. In both sexes there are 17–22 rows of small teeth located towards the back of the mouth which barely protrude past the gum. In males, there are two small, triangular teeth present halfway down the mouth. The overall coloration is dark on top and light below, and both sexes have a white beak. Females are lighter on top and have additional white marking near the genitals. Adult males often carry linear scars that probably result from fighting, and both males and females may display circular scars from cookiecutter shark bites.[2] Females reach at least 5.3 meters (17 feet 6 inches) whereas males reach 5.7 meters (19 feet) and weigh around 1100 kilograms (2400 pounds). They are believed to be around 2.4 meters (7 feet 10 inches) long when born.

Behavior

An adult female, one of five Gray's beaked whales stranded at Port Waikato, New Zealand.

The Gray's beaked whale is very gregarious. It has a tendency to strand in large groups, once involving 20 individuals. Other strandings involved five to eight animals. The upper teeth may be used in holding prey, but it not clear why only this species has them.

Population and distribution

This species typically lives in the Southern Hemisphere between 30 and 45 degrees. Many strandings have occurred off New Zealand, but others have happened off Australia, South Africa, South America, and the Falkland Islands. This species has been sighted in groups off the coast of Madagascar and in the Antarctic area. Oddly, one specimen stranded off the Netherlands, on a different Hemisphere and several thousand miles away from all other strandings. No population estimates exist, but they are believed to be rather common.

Conservation

These whales have not been hunted deliberately and they have not been entangled in fishing gear.

Specimens

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). Mesoplodon grayi. 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.
  2. ^ Gray's Beaked Whale, Australian Museum. Updated 13 October 2009. Retrieved 13 January 2011.

Bibliography

  • Encyclopedia of Marine Mammals. Edited by William F. Perrin, Bernd Wursig, and J.G.M Thewissen. Academic Press, 2002. ISBN 0-12-551340-2
  • Sea Mammals of the World. Written by Randall R. Reeves, Brent S. Steward, Phillip J. Clapham, and James A. Owell. A & C Black, London, 2002. ISBN 0-7136-6334-0
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Mesoplodont whale

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

Mesoplodont whales are fourteen species of whale in the genus Mesoplodon, making it the largest genus in the cetacean order. Two species were described as recently as 1991 (Pygmy Beaked Whale) and 2002 (Perrin's Beaked Whale), and marine biologists predict the discovery of more species in the future. They are the most poorly known group of large mammals. The word mesoplodon comes from the Greek meso- (middle) - hopla (arms) - odon (teeth), and may be translated as 'armed with a tooth in the centre of the jaw'.

Contents

Species

English name (most common first), Latin name:

Longman's Beaked Whale (also known as the Indo-Pacific Beaked Whale) is also sometimes classed in the Mesoplodon genus. However, all recent authorities follow the lead of Joseph Curtis Moore who in the 1960s put it in its own genus - Indopacetus.

Physical description

Beaked whales are typically medium- to large-sized for toothed whales, 3 to 6 meters in length, but diminutive when compared with Bottlenose Whales and Giant Beaked Whales. The females are the same size or larger than males in every species, but the males typically have a bolder coloration and a unique dentition. The lower jaw often forms a huge arch in some species, sometimes extending above the rostrum in a shape comparable to a playground slide. Every species has large (sometimes tusk-like) teeth of variable size, shape, and position. Gray's Beaked Whale is the exception and has numerous small and possibly functional teeth in the lower jaw. The males of most species are covered in scars from the teeth of other males. Both sexes often have bites from cookie-cutter sharks. The dorsal fin is rather small and far between two-thirds and three-quarters down the back of the animal. Information on longevity and lactation is not existent, and information on gestation is nearly so.

Behavior

Most species are very rarely observed, and little is known about their behavior. They are typically found in groups, possibly segregated between sexes. Some species are so uncommon that they have yet to be observed alive. On the surface they are typically very slow swimmers and do not make obvious blows. They have never been observed raising their flukes above the water either. They are all very deep divers, and typically feed entirely on squid.

Conservation

The Mesoplodonts are completely unknown as far as population estimates are concerned. They have been hunted occasionally by the Japanese, but never directly. They are also accidentally captured in drift nets. It is not known what effect this has on the population.

References

  • Encyclopedia of Marine Mammals. Edited by William F. Perrin, Bernd Wursig, and J.G.M Thewissen. Academic Press, 2002.
  • Sea Mammals of the World. Written by Randall R. Reeves, Brent S. Steward, Phillip J. Clapham, and James A. Owell. A & C Black, London, 2002.
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