Spade Toothed Whale
Encyclopedia
The spade-toothed whale, Mesoplodon traversii, is a very little known species
of beaked whale
. It was first named from a partial jaw found on Pitt Island (New Zealand
) in 1872, reported and illustrated in 1873 by James Hector
, and described the next year by John Edward Gray
, who named it in honor of Henry Hammersley Travers, the collector. This was eventually lumped with the strap-toothed whale, starting as early as 1878 (Hector 1878, who in fact never considered the specimen to be specifically distinct). A calvaria
found in the 1950s at White Island (also New Zealand) initially remained undescribed, but later was believed to be from a ginkgo-toothed beaked whale
(Baker and van Helden 1999).
In 1986, a damaged calvaria was found washed up on Robinson Crusoe Island
(Chile
), and was described as a new species, Mesoplodon bahamondi or Bahamonde's beaked whale. The results of DNA sequence
and morphological
comparisons (van Helden et al. 2002) have shown all three finds came from the same species, which is therefore properly known as M. traversii. This species is remarkable since the external appearance is still completely unknown, and it is likely to be the most poorly known large mammal
ian species of our time.
spade of 19th-century whalers.
Despite the rather similar dentition, the spade-toothed whale and strap-toothed whale seem only distantly related. The present species' relationships are not known with certainty, though, because it is very distinct morphologically and DNA sequence information is contradictory and unable to propose a robust phylogenetic hypothesis thus far. Judging from the size of the skull, the species may be between 5.0 and 5.5 meters (16 and 18 feet) in length, perhaps a bit larger.
s and small fish. The young become independent of their mothers probably around one year of age, as in most whales.
The population status of the spade-toothed whale is entirely unknown, but it is unlikely to be abundant.
The sex of the 20th-century specimens is not known. However, by recovering or failing to recover DNA sequences of the Y chromosome
, it could, in theory, be resolved. Note that little material is shared between the Pitt Island specimen and the calvariae, making direct anatomical comparisons problematic.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of beaked whale
Beaked whale
Beaked whales are 21 species of toothed whales, members of the family Ziphiidae, are notable for their elongated beaks. Beaked whales are one of the world's most extreme divers. They can dive for long periods—20 to 30 minutes is common, and 85 minute dives have been recorded—and to...
. It was first named from a partial jaw found on Pitt Island (New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
) in 1872, reported and illustrated in 1873 by James Hector
James Hector
Sir James Hector was a Scottish geologist, naturalist, and surgeon who accompanied the Palliser Expedition as a surgeon and geologist...
, and described the next year by John Edward Gray
John Edward Gray
John Edward Gray, FRS was a British zoologist. He was the elder brother of George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray ....
, who named it in honor of Henry Hammersley Travers, the collector. This was eventually lumped with the strap-toothed whale, starting as early as 1878 (Hector 1878, who in fact never considered the specimen to be specifically distinct). A calvaria
Calvaria (skull)
The calvaria is the upper part of the cranium and surrounds the cranial cavity containing the brain.The calvaria is made up of the frontal, occipital and right and left parietals....
found in the 1950s at White Island (also New Zealand) initially remained undescribed, but later was believed to be from a ginkgo-toothed beaked whale
Ginkgo-toothed Beaked Whale
The ginkgo-toothed beaked whale is a poorly known species of whale even for a beaked whale, and was named for the unusual shape of its dual teeth...
(Baker and van Helden 1999).
In 1986, a damaged calvaria was found washed up on Robinson Crusoe Island
Robinson Crusoe Island
Robinson Crusoe Island , formerly known as Más a Tierra , or Aguas Buenas, is the largest island of the Chilean Juan Fernández archipelago, situated 674 kilometres west of South America in the South Pacific Ocean...
(Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
), and was described as a new species, Mesoplodon bahamondi or Bahamonde's beaked whale. The results of DNA sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
and morphological
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
comparisons (van Helden et al. 2002) have shown all three finds came from the same species, which is therefore properly known as M. traversii. This species is remarkable since the external appearance is still completely unknown, and it is likely to be the most poorly known large mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
ian species of our time.
Physical description
Nothing is known about this species other than cranial and dental anatomy. There are some notable differences between it and other mesoplodonts, such as the relatively large width of the rostrum; altogether it might look most similar to an oversized ginkgo-toothed beaked whale in overall shape, as their skulls are quite alike except in size. The distinguishing character are the very large teeth of the animal, 23 cm (9 inches), close in size to those of strap-toothed whale. The teeth are much wider than the strap-toothed, and a peculiar denticle on the tip of the teeth present on both species is much more pronounced in the spade-toothed whale. The common name was chosen because the part of the tooth that protrudes from the gums, in life, unlike the straplike ones of strap-toothed whales, must have a shape similar to the tip of a flensingFlensing
Flensing is the removing of the outer integument of whales. English whalemen called it "flenching", while American whalemen called it "cutting-in".-Open-boat:-Shore and Bay whaling:...
spade of 19th-century whalers.
Despite the rather similar dentition, the spade-toothed whale and strap-toothed whale seem only distantly related. The present species' relationships are not known with certainty, though, because it is very distinct morphologically and DNA sequence information is contradictory and unable to propose a robust phylogenetic hypothesis thus far. Judging from the size of the skull, the species may be between 5.0 and 5.5 meters (16 and 18 feet) in length, perhaps a bit larger.
Ecology and status
This species has never been seen alive, so nothing is known of its behavior. It is presumably not different from other Mesoplodon of medium size, which are deep-water species living alone or in small groups and which feed on cephalopodCephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
s and small fish. The young become independent of their mothers probably around one year of age, as in most whales.
The population status of the spade-toothed whale is entirely unknown, but it is unlikely to be abundant.
Specimens
- NMNZ 546 - 1872; Pitt Island specimen, apparently male, probably fully adult
- Auckland University School of Biological Sciences MacGregor Collection (unnumbered) - 1950s White Island specimen, probably fully adult
- MNHNC 1156 - 1986; Robinson Crusoe Island specimen, probably fully adult
The sex of the 20th-century specimens is not known. However, by recovering or failing to recover DNA sequences of the Y chromosome
Y chromosome
The Y chromosome is one of the two sex-determining chromosomes in most mammals, including humans. In mammals, it contains the gene SRY, which triggers testis development if present. The human Y chromosome is composed of about 60 million base pairs...
, it could, in theory, be resolved. Note that little material is shared between the Pitt Island specimen and the calvariae, making direct anatomical comparisons problematic.