Dwarf sperm whale[1] |
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Size compared to an average human |
Conservation status |
Data Deficient (IUCN 3.1)[2]
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Scientific classification |
Kingdom: |
Animalia |
Phylum: |
Chordata |
Class: |
Mammalia |
Order: |
Artiodactyla |
Family: |
Kogiidae |
Genus: |
Kogia |
Species: |
K. sima |
Binomial name |
Kogia sima
Owen, 1866 |
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Dwarf sperm whale range |
The dwarf sperm whale (Kogia sima, formerly Kogia simus) is one of three species in the sperm whale family. They are not often sighted at sea, and most extant information comes from the study of stranded carcasses.
Contents
- 1 Taxonomy
- 2 Description
- 3 Diet
- 4 Behavior
- 5 Population and distribution
- 6 Life cycle
- 7 Human interaction
- 8 Conservation
- 9 See also
- 10 References
- 11 External links
Taxonomy
Today, the dwarf sperm whale is generally classified as one of two species, along with the pygmy sperm whale, in the Kogiidae family and Kogia genus. It was not until 1966 that the two species were regarded as separate. Most taxonomists regard the family Kogiidae as belonging to the superfamily Physeteroidea, though some consider this taxon to be a subfamily (Kogiinae) of the family Physeteridae.
Description
The dwarf sperm whale is the smallest species commonly known as a whale. It grows up to 2.7 m (8.9 ft) in length and 250 kilograms (550 lb) in weight— making it smaller than the bigger dolphins. The species makes slow, deliberate movements with little splash or blow and usually lies motionless when at the sea's surface. Consequently it is usually observed only in very calm seas (Beaufort 0-1).
The dwarf sperm whale is similar in appearance and behavior to its cousin the pygmy sperm whale. Identification may be close to impossible at sea – however, the dwarf is slightly smaller and has a larger dorsal fin. The body is mainly bluish gray with a lighter underside with slightly yellow vein-like streaks possibly visible. There is a white false gill behind each eye. The flippers are very short and broad. The top of the snout overhangs the lower jaw, which is small. Dwarfs have long, curved and sharp teeth (0–6 in the upper jaw, between 14 and 26 in the lower). These teeth led to the species being described as the "rat porpoise" in the Lower Antilles.
Like other sperm whales, the dwarf sperm whale has a spermaceti organ in its forehead. Like the pygmy, the dwarf is able to expel a dark reddish substance when frightened or attacked—possibly to put off any predators.
Dwarf sperm whales are usually solitary but have occasionally been seen in small groups.
The brain of the dwarf sperm whale is roughly half a kilogram in mass.[3]
Diet
Dwarf sperm whales feed mainly on squid and crab.
Behavior
Dwarf sperm whales and pygmy sperm whales are unique among cetaceans in using a form of "ink" to evade predation in a manner similar to squid. Both species have a sac in the lower portion of their intestinal tract that contains up to 12 L of dark reddish-brown fluid, which can be ejected to confuse or discourage potential predators.[4]
Population and distribution
The dwarf sperm whale prefers deep water, but is more coastal than the pygmy sperm. Its favorite habitat appears to be just off the continental shelf. In the Atlantic, strandings have been observed in Virginia, United States in the west and Spain and the United Kingdom in the east, and as far south as southern Brazil and the tip of Africa. In the Indian Ocean, specimens have been found on the south coast of Australia and on many places along the Indian Ocean's northern coast - from South Africa right round to Indonesia. In the Pacific, the known range includes the Japanese coast and British Columbia. No global population estimates have been made. One survey estimated a population of about 11,000 in the eastern Pacific.
Life cycle
The calving season lasts four to five months. Pregnancy lasts for 9 to 11 months. The newborn calf is about one meter long.[5] Males reach puberty at 2.0m and become sexually mature at 2.1 to 2.2 m.[6]
Human interaction
The dwarf sperm whale was actively hunted by commercial whalers. Occasional harpoon kills are still made by Indonesian and Japanese fishermen. Since the dwarf is more coastal than the pygmy, it may be more vulnerable to human activities such as fishing and pollution. Insufficient data exists as to whether such activities threaten the species survival.
Conservation
The dwarf sperm whale is covered by the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS).[7] The species is further included in the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia (Western African Aquatic Mammals MoU)[8] and the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU).[9]
See also
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Cetaceans portal |
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Marine life portal |
References
- ^ Mead, J. G.; Brownell, R. L., Jr. (2005). "Order Cetacea". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. p. 737. ISBN 978-0-8018-8221-0. OCLC 62265494.
- ^ Taylor, B.L.; Baird, R.; Barlow, J.; Dawson, S.M.; Ford, J.K.B.; Mead, J.G.; Notarbartolo di Sciara, G.; Wade, P.; Pitman, R.L. (2012). "Kogia sima". IUCN Red List of Threatened Species. Version 2014.3. International Union for Conservation of Nature. Retrieved 2015-01-11.
- ^ L Marino, K Sudheimer, DA Pabst, WA McLellan, and JI Johnson (2003). Magnetic resonance images of the brain of a dwarf sperm whale (Kogia simus). Journal of Anatomy, 203(1): 57–76
- ^ "Dwarf sperm whale (Kogia sima)". NOAA Fisheries Office of Protected Resources web site. NOAA. 2014-10-20. Archived from the original on 2013-10-03. Retrieved 2015-01-11.
- ^ Kristin Petrie. Dwarf Sperm Whales. pg 16
- ^ David Nagorsen (1985). Kogia simus. Mammalian Species 239
- ^ Official website of the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area
- ^ Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia
- ^ Official webpage of the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region
- Pygmy and Dwarf Sperm Whales by Donald F. McAlpine in Encyclopedia of Marine Mammals (2002), San Diego: Academic Press, pp. 1007–1009, ISBN 0-12-551340-2
- Whales Dolphins and Porpoises, Mark Carwardine, Dorling Kindersley Handbooks, ISBN 0-7513-2781-6
- National Audubon Society Guide to Marine Mammals of the World, Reeves, Stewart, Clapham and Powell, ISBN 0-375-41141-0
External links
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Wikispecies has information related to: Kogia sima |
Media related to Kogia sima at Wikimedia Commons
- Whale & Dolphin Conservation Society (WDCS)
- Voices in the Sea - Sounds of the Dwarf sperm Whale
Extant Cetacea species
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- Kingdom Animalia
- Phylum Chordata
- Class Mammalia
- Infraclass Eutheria
- Superorder Laurasiatheria
- (unranked) Cetartiodactyla
- (unranked) Whippomorpha
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Suborder Mysticeti (Baleen whales)
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Balaenidae |
Balaena
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- Bowhead whale (B. mysticetus)
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Eubalaena
(Right whales)
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- Southern right whale (E. australis)
- North Atlantic right whale (E. glacialis)
- North Pacific right whale (E. japonica)
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Balaenopteridae
(Rorquals) |
Balaenoptera
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- Common minke whale (B. acutorostrata)
- Antarctic minke whale (B. bonaerensis)
- Sei whale (B. borealis)
- Bryde's whale (B. brydei)
- Pygmy Bryde's whale (B. edeni)
- Blue whale (B. musculus)
- Omura's whale (B. omurai)
- Fin whale (B. physalus)
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Megaptera
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- Humpback whale (M. novaeangliae)
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Eschrichtiidae |
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Neobalaenidae |
Caperea
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- Pygmy right whale (C. marginata)
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Suborder Odontoceti (Toothed whales) (cont. below)
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Delphinidae
(Oceanic dolphins) |
Cephalorhynchus
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- Commerson's dolphin (C. commersonii)
- Chilean dolphin (C. eutropia)
- Haviside's dolphin (C. heavisidii)
- Hector's dolphin (C. hectori)
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Delphinus
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- Long-beaked common dolphin (D. capensis)
- Short-beaked common dolphin (D. delphis)
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Feresa
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- Pygmy killer whale (F. attenuata)
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Globicephala
(Pilot whales)
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- Short-finned pilot whale (G. macrorhynchus)
- Long-finned pilot whale (G. melas)
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Grampus
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- Risso's dolphin (G. griseus)
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Lagenodelphis
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- Fraser's dolphin (L. hosei)
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Lagenorhynchus
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- Atlantic white-sided dolphin (L. acutus)
- White-beaked dolphin (L. albirostris)
- Peale's dolphin (L. australis)
- Hourglass dolphin (L. cruciger)
- Pacific white-sided dolphin (L. obliquidens)
- Dusky dolphin (L. obscurus)
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Lissodelphis
(Right whale dolphins)
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- Northern right whale dolphin (L. borealis)
- Southern right whale dolphin (L. peronii)
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Orcaella
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- Irrawaddy dolphin (O. brevirostris)
- Australian snubfin dolphin (O. heinsohni)
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Orcinus
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Peponocephala
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- Melon-headed whale (P. electra)
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Pseudorca
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- False killer whale (P. crassidens)
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Sotalia
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- Tucuxi (S. fluviatilis)
- Costero (S. guianensis)
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Sousa
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- Indo-Pacific humpback dolphin (S. chinensis)
- Atlantic humpback dolphin (S. teuszii)
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Stenella
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- Pantropical spotted dolphin (S. attenuata)
- Clymene dolphin (S. clymene)
- Striped dolphin (S. coeruleoalba)
- Atlantic spotted dolphin (S. frontalis)
- Spinner dolphin (S. longirostris)
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Steno
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- Rough-toothed dolphin (S. bredanensis)
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Tursiops
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- Indo-Pacific bottlenose dolphin (T. aduncus)
- Burrunan dolphin (T. australis)
- Common bottlenose dolphin (T. truncatus)
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Suborder Odontoceti (Toothed whales) (cont. above)
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Monodontidae |
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Phocoenidae
(Porpoises) |
Neophocaena
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- Finless porpoise (N. phocaeniodes)
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Phocoena
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- Spectacled porpoise (P. dioptrica)
- Harbor porpoise (P. phocoena)
- Vaquita (P. sinus)
- Burmeister's porpoise (P. spinipinnis)
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Phocoenoides
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- Dall's porpoise (P. dalli)
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Physeteridae |
Physeter
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- Sperm whale (P. macrocephalus)
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Kogiidae |
Kogia
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- Pygmy sperm whale (K. breviceps)
- Dwarf sperm whale (K. simus)
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Iniidae |
Inia
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- Amazon river dolphin (I. geoffrensis)
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Lipotidae |
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Platanistidae |
Platanista
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- Ganges and Indus River dolphin (P. gangetica)
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Pontoporiidae |
Pontoporia
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- La Plata dolphin (P. blainvillei)
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Ziphiidae
(Beaked whales) |
Berardius
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- Arnoux's beaked whale (B. arnuxii)
- Baird's beaked whale (B. bairdii)
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Hyperoodon
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- Northern bottlenose whale (H. ampullatus)
- Southern bottlenose whale (H. planifrons)
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Indopacetus
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- Tropical bottlenose whale (I. pacificus)
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Mesoplodon
(Mesoplodont
whales)
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- Sowerby's beaked whale (M. bidens)
- Andrews' beaked whale (M. bowdoini)
- Hubbs' beaked whale (M. carlhubbsi)
- Blainville's beaked whale (M. densirostris)
- Gervais' beaked whale (M. europaeus)
- Ginkgo-toothed beaked whale (M. ginkgodens)
- Gray's beaked whale (M. grayi)
- Hector's beaked whale (M. hectori)
- Strap-toothed whale (M. layardii)
- True's beaked whale (M. mirus)
- Perrin's beaked whale (M. perrini)
- Pygmy beaked whale (M. peruvianus)
- Stejneger's beaked whale (M. stejnegeri)
- Spade-toothed whale (M. traversii)
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Tasmacetus
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- Shepherd's beaked whale (T. sheperdi)
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Ziphius
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- Cuvier's beaked whale (Z. cavirostris)
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