Ginkgo-toothed beaked whale

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Ginkgo-toothed beaked whale. Source. FAO

Ginko-toothed beaked whale (scientific name: Mesoplodon ginkgodens) is one of 21 species of beaked whales (Hyperoodontidae or Ziphiidae), medium-sized whales with distinctive, long and narrow beaks and dorsal fins set far back on their bodies. They are marine mammals within the order of cetaceans.

The IUCN Red List notes that "the ginkgo-toothed beaked whale is known from only a few dozen widely-scattered strandings and captures (no confirmed sightings) in temperate and tropical waters of the Indo-Pacific Ocean, from Sri Lanka east to the shores of North America (California) and the Galápagos Islands (Mead 1989; Pitman 2002). There have been a few records from New Zealand and Australia, indicating that this species also inhabits the southern Indo-Pacific. Most records are from the seas around Japan. Sightings of what may have been this species were also made in the Arabian Sea. It is generally hypothesized that the range is continuous across the Pacific and at least to the eastern Indian Ocean, but until the species can be reliably identified at sea, its true distribution will probably remain unknown (MacLeod et al. 2006)."

As a result, almost nothing is known of the ginkgo-toothed beaked whale. Nothing about its behavior or feeding habits has been reported, and its geographical distribution is estimated from a very small sample. Most records are from Asian waters, where a few were harpooned in fisheries. As with other beaked whales, adult males can be identified by their distinctively-shaped teeth, which differ among the various beaked whale species, but females and juveniles are very difficult to identify in the field by species.

Mesoplodon-ginkgodens1.jpg Ginko-toothed beaked whale. Source: Andreas Rechmitzer
487px-ginkgo-toothed beaked whale size.png Size comparison of an average human against Ginko-toothed beaked whale. Source: Chris Huh

Conservation Status:
Data Deficient

Scientific Classification

Kingdom: Animalia
Phylum:--- Chordata
Class:------ Mammalia
Order:-------- Cetacea
Family:-------- Hyperoodontidae
Genus:--------- Mesoplodon
Species:-------- Mesoplodon ginkgodens (Nishiwaki and Kamiya, 1958)

Common Names:
Gingko beaked whale
Ginko-toothed beaked whale
Japanese beaked whale
Gingko-toothed whale
Ginkgo-toothed beaked whale
ginkgo-toothed whale

Physical description

Adult males are darkly colored over the entire body and have a spattering of white spots over the posterior one third of the ventral surface. It is unclear whether these white spots are pigmentation or parasitic scars. The only pictures of females show a medium grey body and light grey ventrum. Male ginkgo-toothed beaked whale are characterized by a single pair of protruding lower teeth that are shaped like a ginkgo leaf.

Overarching physical features include endothermic metbolism and bilateral symmetry. the adult length ranges up to 4.8 meters (m) for males; up to 4.9 m for females

Distribution and movements

Distribution of Ginko-toothed beaked whale.png.jpegThe IUCN Red List notes:

The ginkgo-toothed beaked whale is known from only a few dozen widely-scattered strandings and captures (no confirmed sightings) in temperate and tropical waters of the Indo-Pacific Ocean, from Sri Lanka east to the shores of North America (California) and the Galápagos Islands (Mead 1989; Pitman 2002). There have been a few records from New Zealand and Australia, indicating that this species also inhabits the southern Indo-Pacific. Most records are from the seas around Japan. Sightings of what may have been this species were also made in the Arabian Sea. It is generally hypothesized that the range is continuous across the Pacific and at least to the eastern Indian Ocean, but until the species can be reliably identified at sea, its true distribution will probably remain unknown (MacLeod et al. 2006).

Habitat

These whales have been found stranded off Japan, California, Mexico, Taiwan, Indonesia and Sri Lanka. The species appears to prefer warm, open water. Because they are seldom seen, it is assumed that they prefer the open ocean to coastalwaters.

Feeding behavior

Very little is known about this whale. It is presumed to have food habits like those of other beaked whales and probably subsists on squid and open-water fishes.

Animal Foods: Fish; Mollusks

Threats and conservation status

The IUCN Red List notes:

There are no estimates of abundance, but the species does not appear to be very common anywhere. There is no information on trends in the global abundance of this species.

References

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Citation

Encyclopedia of Life (2011). Ginkgo-toothed beaked whale. ed. C. Michael Hogan. Encyclopedia of Earth. National Council for Science and Environment. Washington DC. Retrieved from http://editors.eol.org/eoearth/wiki/Ginkgo-toothed_beaked_whale
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