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Mesoplodon ginkgodensginkgo-toothed beaked whale

By Vu Quach

Geographic Range

Ginkgo-toothed beaked whales (Mesoplodon ginkgodens) reside in tropical and temperate waters throughout the Pacific and Indian Oceans. The range of this species is known from 16 specimens that were found stranded on the coasts of Japan, Taiwan, Sri Lanka, Indonesia, Australia, Southwest California, Mexico and Ecuador. There have been no confirmed sightings of live species in open oceans; however, it is presumed that they are found in the Indian and Pacific Oceans from southern California to the southern tip of India. (NISHIWAKI and KAMIYA, 1958; Nishiwaki and KAMIYA, 1989; Palacios, 1996)

Habitat

No habitat information is available for Mesoplodon ginkgodens. The habits of close relatives, Mesoplodon densirostris and Mesoplodon peruvianus, suggest that M. ginkodens prefers slightly cooler areas within the temperate/tropical zone and also upwelling regions. Upwelling regions are highly productive due to nutrient-rich bottom waters cycling to the surface. (Moore, 1963; Palacios, 1996)

Physical Description

Based on stranded specimens, adult males appear to be mainly dark grey, darker dorsally and slightly paler ventrally. The rostrum and lower jaw of Mesoplodon ginkgodens both have a small pale gray patch. Adult females are generally paler than males. Adults of both genders display white spots and small blade-like scars. White spots are found towards the posterior end of the ventral surface and are believed to be either from natural pigmentation or parasitism. Mesoplodon ginkgodens has a pair of distinguishing ginkgo-shaped teeth, one on each side of the lower jaw towards the middle of the beak. In males they erupt beyond the gum line, but in females they do not. This characteristic tooth is present in all males in the Mesoplodon genus. Mesoplodon ginkodens is distinguished from other Mesoplodon by the great width of its ginko-shaped tooth, which is always >100mm. Males and females reach a maximum of 5.3 meters. (Moore, 1963; Palacios, 1996)

  • Sexual Dimorphism
  • sexes colored or patterned differently
  • Range length
    5.3 (high) m
    17.39 (high) ft

Reproduction

There is no information available regarding the mating system of Mesoplodon ginkgodens. (Nishiwaki, et al., 1972)

There is no information available regarding the general reproductive behavior of Mesoplodon ginkgodens.

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual
  • viviparous

While no parental investment information specific to << Mesoplodon ginkgodens>> is available, as mammals, it can be assumed that females likely provide their young with milk and protection until weaning.

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
  • pre-weaning/fledging
    • provisioning
      • female
  • pre-independence
    • provisioning
      • female

Lifespan/Longevity

No information is available.

Behavior

Males of all species of Mesoplodon use their enlarged teeth for fighting, which they do by swimming at each other and making contact with these teeth. Females also may be scarred, but scars are more prevalent in males. Levels of aggression differ within species and can be assessed according to the number of scars on the bodies of members of each sex. Because Mesoplodon ginkgodens exhibit the least amount of scars of any Mesoplodon, it is presumed that they are the least aggressive of all Mesoplodon species. While there is no information available regarding diving and group behavior in M. ginkgodens, there is information for their close relatives Mesoplodon stejnegeri, which live in small pods that range from 5 to 15 members and dive and surface in unison. There is no information available concerning migration in M. ginkgodens. (Loughlin and Perez, 1985; MacLeod, 2000)

Home Range

There is no information available regarding home range in Mesoplodon ginkgodens.

Communication and Perception

Although there is no information ragarding communication and perception in Mesoplodon ginkgodens, studies of echolocation in numerous other Mesoplodon show that they use echolocation to navigate and find prey. It is likely that frequency-modulated pulses differ by species. Pulses probably vary according to the nature of activities being conducted. (Baumann-Pickering, et al., 2010)

Food Habits

Based on findings of similar species and on the nature of their teeth, Mesoplodon ginkgodens probably feeds on squid and fish. Some species specialize on one prey more than the other, but the feeding habits of M. ginkgodens are unknown. In addition to fish and squid, a small amount of crustaceans have been found in the stomachs of other Mesoplodon species. (Culik, 2010; Loughlin and Perez, 1985)

  • Animal Foods
  • fish
  • mollusks
  • aquatic crustaceans

Predation

Photographs of distinctive bite marks on Mesoplodon ginkgodens indicate that their main predators may be sharks, especially cookiecutter sharks.

Ecosystem Roles

Mesoplodon ginkgodens feed on primarily squid and fish and in doing so, likely influence the populations of these animals. In addition, Mesoplodon ginkgodens serve as host to ocean parasites such as the lampreys. (Loughlin and Perez, 1985; Nishiwaki and KAMIYA, 1989)

Commensal/Parasitic Species

Economic Importance for Humans: Positive

There are no known positive effects of Mesoplodon ginkgodens on humans.

Economic Importance for Humans: Negative

There are no known adverse effects of Mesoplodon ginkgodens on humans.

Conservation Status

Because there are so few wild encounters with Mesoplodon ginkgodens, it is difficult to determine population trends to assess potential conservation needs. This species is listed as "data deficient" on the IUCN's Red List of Threatened Species, and is listed under Appendix II on the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Mesoplodon ginkgodens is not considered as part of the United States Endangered Species Act.

Contributors

Vu Quach (author), University of Michigan-Ann Arbor, Phil Myers (editor), University of Michigan-Ann Arbor, John Berini (editor), Animal Diversity Web Staff.

Glossary

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

echolocation

The process by which an animal locates itself with respect to other animals and objects by emitting sound waves and sensing the pattern of the reflected sound waves.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

molluscivore

eats mollusks, members of Phylum Mollusca

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

pelagic

An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).

piscivore

an animal that mainly eats fish

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Baker, A., A. van Helden. 1999. New records of beaked whales, Genus Mesoplodon, from New Zealand (Cetacea: Ziphiidae). Journal of the Royal Society of New Zealand, 29: 235-244. Accessed March 14, 2011 at http://www.royalsociety.org.nz/media/publications-journals-nzjr-1999-015.pdf.

Baumann-Pickering, S., S. Wiggins, E. Roth, M. Roch, H. Schnitzler, J. Hildebrand. 2010. Echolocation signals of a beaked whale at Palmyra Atoll. The Journal of the Acoustical Society of America, 127: 3790-3799.

Culik, B. 2010. "Odontocetes - the toothed whales. Distribution, Behaviour, Migration and Threats" (On-line). CMS. Accessed April 06, 2011 at http://www.cms.int/reports/small_cetaceans/data/m_ginkgodens/m_ginkgodens.htm.

Loughlin, T., M. Perez. 1985. Mesoplodon stejnegeri. Mammalian Species, 250: 1-6.

MacLeod, C. 1998. Intraspecifc scarring in odontocete cetaceans: an indicator of male `quality' in aggressive social interactions?. The Zoological Society of London, 244: 71-77.

MacLeod, C. 2000. Species Recognition as a Possible Function for Variations in Position and Shape of the Sexually Dimorphic Tusks of Mesoplodon Whales. Evolution, 54: 2171-2173.

Moore, J. 1963. Recognizing certain species of beaked whales of the Pacific Ocean. AMER MIDLAND NAT, 70: 396-428.

NISHIWAKI, M., T. KAMIYA. 1958. A beaked whale Mesoplodon stranded at Oiso Beach. BULL JAPANESE SOC SCI FISH, 24: 445-448.

Nishiwaki, , KAMIYA. 1989. "Mesoplodon ginkgodens" (On-line). Accessed March 14, 2011 at http://www.bucknell.edu/msw3/browse.asp?s=y&id=14300163.

Nishiwaki, M., T. Kasuya, K. Kureha, N. Oguro. 1972. FURTHER COMMENTS ON MESOPLODON-GINKGODENS. Scientific Reports of the Whales Research Institute Tokyo, 24: 43-56.

Palacios, D. 1996. On the specimen of the ginkgo-toothed beaked whale, Mesoplodon ginkgodens, from the Galapagos Islands. Marine Mammal Science, 12: 444-446. Accessed March 14, 2011 at http://onlinelibrary.wiley.com.proxy.lib.umich.edu/doi/10.1111/j.1748-7692.1996.tb00596.x/pdf.

Perrin, W. 1958. "Mesoplodon ginkgodens" (On-line). Accessed March 14, 2011 at http://www.marinespecies.org/cetacea/aphia.php?p=taxdetails&id=231407.

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