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Pygmy sperm whale

August 18, 2023

The pygmy sperm whale (Kogia breviceps) is one of two extant species in the family Kogiidae in the sperm whale superfamily. They are not often sighted at sea, and most of what is known about them comes from the examination of stranded specimens.

Pygmy sperm whale[1]
Individual washed ashore on Hutchinson Island, Florida
Size compared to an average human
CITES Appendix II (CITES)[3]
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea
Family: Kogiidae
Genus: Kogia
Species:
K. breviceps
Binomial name
Kogia breviceps
(Blainville, 1838)
Pygmy sperm whale range
Synonyms

Physeter breviceps

Taxonomy

 
Illustration from the 19th century

The pygmy sperm whale was first described by naturalist Henri Marie Ducrotay de Blainville in 1838. He based this on the head of an individual washed up on the coasts of Audierne in France in 1784, which was then stored in the Muséum d'histoire naturelle. He recognized it as a type of sperm whale and assigned it to the same genus as the sperm whale (Physeter macrocephalus) as Physeter breviceps. He noted its small size and nicknamed it "cachalot a tête courte"–small-headed sperm whale; further, the species name breviceps is Latin for "short-headed".[4] In 1846, zoologist John Edward Gray erected the genus Kogia for the pygmy sperm whale as Kogia breviceps, and said it was intermediate between the sperm whale and dolphins.[5]

In 1871, mammalogist Theodore Gill assigned it and Euphysetes (now the dwarf sperm whale, Kogia sima) to the subfamily Kogiinae, and the sperm whale to the subfamily Physeterinae.[6] Both have now been elevated to the family level. In 1878, naturalist James Hector synonymized the dwarf sperm whale with the pygmy sperm whale, with both being referred to as K. breviceps until 1998.[7]

Description

 
Pygmy sperm whale skeleton

The pygmy sperm whale is not much larger than many dolphins. They are about 1.2 m (3 ft 11 in) at birth, growing to about 3.5 m (11 ft) at maturity. Adults weigh about 400 kg (880 lb). The underside is a creamy, occasionally pinkish colour and the back and sides are a bluish grey; however, considerable intermixing occurs between the two colours. The shark-like head is large in comparison to body size, given an almost swollen appearance when viewed from the side. A whitish marking, often described as a "false gill", is seen behind each eye.[8][9]

The lower jaw is very small and slung low.[10] The blowhole is displaced slightly to the left when viewed from above facing forward.[10] The dorsal fin is very small and hooked; its size is considerably smaller than that of the dwarf sperm whale and may be used for diagnostic purposes.[10]

Anatomy

 
Closeup of the head

Like its giant relative, the sperm whale, the pygmy sperm whale has a spermaceti organ in its forehead (see sperm whale for a discussion of its purpose). It also has a sac in its intestines that contains a dark red fluid. The whale may expel this fluid when frightened, perhaps to confuse and disorient predators.[11]

Dwarf and pygmy sperm whales possess the shortest rostrum of current day cetaceans with a skull that is greatly asymmetrical.[12]

Pygmy sperm whales have from 50 to 55 vertebrae, and from 12 to 14 ribs on either side, although the latter are not necessarily symmetrical, and the hindmost ribs do not connect with the vertebral column. Each of the flippers has seven carpals, and a variable number of phalanges in the digits, reportedly ranging from two in the first digit to as many as 10 in the second digit. No true innominate bone exists; it is replaced by a sheet of dense connective tissue. The hyoid bone is unusually large, and presumably has a role in the whale's suction feeding.[9]

 
Pygmy sperm whale skull viewed from the side.

Teeth

The pygmy sperm has between 20 and 32 teeth, all of which are set into the rostral part of the lower jaw.[13] Unusually, adults lack enamel due to a mutation in the enamelysin gene,[14] although enamel is present in very young individuals.[9]

 
Pygmy whale teeth on its lower rostrum

Melon

 

Like other toothed whales, the pygmy sperm whale has a "melon", a body of fat and wax in the head that it uses to focus and modulate the sounds it makes.[15] The inner core of the melon has a higher wax content than the outer cortex. The inner core transmits sound more slowly than the outer layer, allowing it to refract sound into a highly directional beam.[16] Behind the melon, separated by a thin membrane, is the spermaceti organ. Both the melon and the spermaceti organ are encased in a thick fibrous coat, resembling a bursa.[17] The whale produces sound by moving air through the right nasal cavity, which includes a valvular structure, or museau de singe, with a thickened vocal reed, functioning like the vocal cords of humans.

Stomach

The stomach has three chambers. The first chamber, or forestomach, is not glandular, and opens directly into the second, fundic chamber, which is lined by digestive glands. A narrow tube runs from the second to the third, or pyloric, stomach, which is also glandular, and connects, via a sphincter, to the duodenum. Although fermentation of food material apparently occurs in the small intestine, no caecum is present.[18]

Brain

The rostroventral dura of the brain contains a significant concentration of magnetite crystals, which suggests that K. breviceps can navigate by magnetoreception.[9]

Studies have also shown that compared to the sperm whale, the pygmy sperm whale brain has significantly fewer neurons, which may be connected to a decreased complexity in social interaction and group-based living.[19]

Echolocation

Like all toothed whales, the pygmy sperm whale hunts prey by echolocation. Sound produced for echolocation by many odontocetes come in the form of high-frequency clicks.[20] The frequencies it uses are mostly ultrasonic,[16] peaking around 125 kHz.[20] The clicks from their echolocation has been recorded to last an average of 600 microseconds. When closing in on prey, the click repetition rate starts at 20 Hz and then begins to rise when nearing the target.[20]

The pulse sounds that pygmy sperm whales make for echolocation are generated primarily from the museau de singe or monkey's muzzle, which is an anatomical structure located within the whale's skull that produces sound when air passes through its lips.[16] The sound from the museau de singe is transferred to the attached cone of the spermaceti organ. Unique from other odontocetes, the spermaceti organ contacts the posterior of the whale's melon.[16] Fat from the core of the spermaceti organ helps direct sonic energy from the museau de singe to the melon.[16] The melon acts as a sonic magnifier and gives directionality to sound pulses, making echolocation more efficient. Fat on the interior of the melon has a lower molecular weight lipid than the surrounding outer melon.[16] Since the sound waves move from a lower velocity material to a higher one during sound production, the sound undergoes inward refraction and becomes increasingly focused. Variation in fat density within the melon ultimately contributes to the production of highly directional, ultrasonic sound beams in front of the melon. The combined melon and spermaceti organ system cooperate to focus echolocative sounds.

Like in most odontocetes, the known echoreception apparatus used by the pygmy sperm whale is linked to the fat-filled lower mandibles within the skull.[16] However, compositional topography of the pygmy sperm whale's skull indicates abnormally large fatty jowls surrounding the mandibles, suggesting a more intricate echoreception apparatus.[16] Additionally, an unusual cushion structure, of porous and spongy texture, found behind the museau de singe has been hypothesized of being a possible "pressure receptor".[16] The positioning of this cushion structure in close proximity to the largest cavities closest to the museau de singe may suggest that it is a sound absorber used for echoreception.

Reproduction

See also: Whale reproduction

Although firm details concerning pygmy sperm whale reproduction are limited, they are believed to mate from April to September in the Southern Hemisphere and March to August in the Northern Hemisphere.[9] These whales become sexually mature at age 4-5, and like virtually all mammals, are iteroparous (reproducing many times during their lives). Once a female whale is impregnated, the average gestation period lasts 9–11 months, and unusually for cetaceans, the female gives birth to a single calf head-first.[21] Newborn calves are about 1.2 metres (3 ft 11 in) in length, weighing 50 kg, and are weaned around one year of age.[9] They are believed to live up to age 23.

Behaviour

The whale makes very inconspicuous movements. It rises to the surface slowly, with little splash or blow, and remains there motionless for some time. In Japan, the whale was historically known as the "floating whale" because of this. Its dive is equally lacking in grand flourish - it simply drops out of view. The species has a tendency to back away from rather than approach boats. Breaching has been observed, but is not common. [22] [23]

Pygmy sperm whales are normally either solitary or found in pairs,[24] but have been seen in groups up to six.[25] Dives have been estimated to last an average of 11 minutes, although longer dives up to 45 minutes have been reported.[9] The ultrasonic clicks of pygmy sperm whales range from 60 to 200 kHz, peaking at 125 kHz,[20] and the animals also make much lower-frequency "cries" at 1 to 2 kHz.[26]

Diet/foraging behavior

Analysis of stomach contents suggests that pygmy sperm whales feed primarily on cephalopods, most commonly including bioluminescent species found in midwater environments. Most of the cephalopod hunting is known to be pelagic, and fairly shallow, within the first 100 m of the surface.[27] The most common prey are reported to include glass squid, and lycoteuthid and ommastrephid squid, although the whales also consume other squid, and octopuses. They have also been reported to eat some deep-sea shrimps, but, compared with dwarf sperm whales, relatively few fish.[9]

Predators may include great white sharks[28] and killer whales.[29]

Pygmy sperm whales and dwarf 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 tracts that contains up to 12 liters of dark reddish-brown fluid, which can be ejected to confuse or discourage potential predators.[30]

Population and distribution

Pygmy sperm whales are found throughout the tropical and temperate waters of the Atlantic, Pacific, and Indian Oceans,[9] and occasionally among colder waters such as off Russia.[31][32] However, they are rarely sighted at sea, so most data come from stranded animals - making a precise range and migration map difficult. They are believed to prefer off-shore waters, and are most frequently sighted in waters ranging from 400 to 1,000 m (1,300 to 3,300 ft) in depth, especially where upwelling water produces local concentrations of zooplankton and animal prey.[33] Their status is usually described as rare, but occasional patches of higher-density strandings suggest they might be more common than previously estimated. The total population is unknown.

Fossils identified as belonging to K. breviceps have been recovered from Miocene deposits in Italy, Japan, and southern Africa.[9]

Human interaction

Pygmy sperm whales have never been hunted on a wide scale. Land-based whalers have hunted them from Indonesia, Japan, and the Lesser Antilles. This species was impacted by whaling in the 18th and 19th centuries, as sperm whales were especially sought after by whalers for their sperm oil, produced by the spermaceti organ. The oil was used to fuel kerosene lamps. Ambergris, a waste product produced by the whales, was also valuable to whalers as it was used by humans in cosmetics and perfume.[34]

They were not as heavily hunted as their larger counterpart Physeter macrocephalus, the sperm whale, which are typically 120,000 lb, thus preferred by whalers.[35] The pygmy sperm whale is also rather inactive and slow rising when coming to the surface and as such do not bring much attention to themselves. However, they were easy targets, as they tended to swim slowly and lie motionless at the surface.[36]

Individuals have also been recorded killed in drift nets. Some stranded animals have been found with plastic bags in their stomachs, which may be a cause for concern. Whether these activities are causing long-term damage to the survival of the species is not known.

Pygmy sperm whales do not do well in captivity.[37][38] The longest recorded survival in captivity is 21 months, and most captive individuals die within one month, mostly due to dehydration or dietary problems.[39]

Pygmy sperm whales have been reported as being forced to change their diets and foraging behaviors due to anthropological factors such as deep-sea trawling and increased fishing for cephalopods off the coast of many Southeast Asian countries. [27]

Conservation

In 1985, the International Whaling Commission ended sperm whaling.[36]

The pygmy sperm whale is covered by the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS)[40] and the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS).[41] 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)[42] and the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU).[43]

As not much is known about this species, as well as due to the whaling and conservation laws in place for marine mammals, it is listed as “lower risk least concern” in the IUCN Red list.[36] However, it faces some modern day issues; it is one of the most common stranded species in Florida sound. Due to its slow-moving and quiet nature, the species is at a higher risk of boat strikes.[44] Its small size also allows for it to become a byproduct of commercial fishing, caught in seine nets.[36] Anthropogenic noise caused by military activity and shipping is another issue affecting this species, as it echolocates. Pygmy sperm whales have also repeatedly been found stranded with plastic in their stomachs.[44]

Specimens

  • MNZ MM002651, collected Hawke's Bay, New Zealand, no date data

See also


References

  1. ^ Mead, J. G.; Brownell, R. L. Jr. (2005). "Order Cetacea". In Wilson, D. E.; Reeder, D. M. (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. p. 737. ISBN 978-0-8018-8221-0. OCLC 62265494.
  2. ^ Kiszka, J.; Braulik, G. (2020). "Kogia breviceps". IUCN Red List of Threatened Species. 2020: e.T11047A50358334. doi:10.2305/IUCN.UK.2020-2.RLTS.T11047A50358334.en. Retrieved 19 November 2021.
  3. ^ "Appendices | CITES". cites.org. Retrieved 2022-01-14.
  4. ^ de Blainville, M. H. (1838). "Sur les Cachalot" [On the Sperm Whales]. Annales Françaises et Étrangères d'Anatomie et de Physiologie (in French). 2: 335–337.
  5. ^ Gray, J. E. (1846). "Zoology of the Voyage of H. M. S. Erebus & Terror Under the Command of Captain Sir James Clark Ross, R. N., F. R. S., During the Years 1839 to 1843". Mammalia. 1: 22.
  6. ^ Gill, T. (1871). "The Sperm Whales, Giant and Pygmy". American Naturalist. 4 (12): 725–743. doi:10.1086/270684.
  7. ^ Rice, D. W. (1998). Marine Mammals of the World: Systematics and Distribution (PDF). Society for Marine Mammalogy. pp. 83–84. ISBN 978-1-891276-03-3.
  8. ^ Roest, A.I. (1970). "Kogia simus and other cetaceans from San Luis Obispo County, California". Journal of Mammalogy. 51 (2): 410–417. doi:10.2307/1378507. JSTOR 1378507.
  9. ^ a b c d e f g h i j Bloodworth, B.E. & Odell, D.K. (2008). "Kogia breviceps (Cetacea: Kogiidae)". Mammalian Species. 819: Number 819: pp. 1–12. doi:10.1644/819.1.
  10. ^ a b c "Pygmy Sperm Whale". www.acsonline.org. Retrieved 2022-04-06.
  11. ^ Scott, M.D. & Cordaro, J.G. (1987). "Behavioral observations of the dwarf sperm whale, Kogia simus". Marine Mammal Science. 3 (4): 353–354. doi:10.1111/j.1748-7692.1987.tb00322.x.
  12. ^ Mcalpine, Donald F. "Pygmy and dwarf sperm whales: Kogia breviceps and K. sima." Encyclopedia of Marine Mammals (Second Edition). 2009. 936-938.
  13. ^ Bloodworth Brian E., Odell Daniel K. (2008). "Kogia breviceps". Mammalian Species. 819: 1–12. doi:10.1644/819.1.
  14. ^ Meredith, R. W.; Gatesy, J.; Cheng, J.; Springer, M. S. (2010). "Pseudogenization of the tooth gene enamelysin (MMP20) in the common ancestor of extant baleen whales". Proceedings of the Royal Society B: Biological Sciences. 278 (1708): 993–1002. doi:10.1098/rspb.2010.1280. PMC 3049022. PMID 20861053.
  15. ^ Clarke, M.R. (2003). "Production and control of sound by the small sperm whale, Kogia breviceps and K. sima and their implications for other Cetacea". Journal of the Marine Biological Association of the United Kingdom. 83 (2): 241–263. doi:10.1017/S0025315403007045h. S2CID 84103043.
  16. ^ a b c d e f g h i R., Karol; C., Litchfield; D., Caldwell; M., Caldwell (1978). Compositional topography of melon and spermaceti organ lipids in the pygmy sperm whale Kogia breviceps: Implications for echolocation. Marine Biology , Volume 47 (2)
  17. ^ Cranford, T.W.; et al. (1996). "Functional morphology and homology in the odontocete nasal complex: implications for sound generation". Journal of Morphology. 228 (2): 223–285. doi:10.1002/(SICI)1097-4687(199606)228:3<223::AID-JMOR1>3.0.CO;2-3. PMID 8622183. S2CID 35653583.
  18. ^ Hagey, L.R.; et al. (1993). "Biliary bile acid composition of the Physeteridae (sperm whales)". Marine Mammal Science. 9 (1): 23–33. doi:10.1111/j.1748-7692.1993.tb00423.x.
  19. ^ Poth, Fung, Gunturkun, Ridgway (2005-02-25). "Neuron numbers in sensory corticies of five delphinids compared to a physterid, the pygmy perm whale". Brain Research Bulletin. 66 (357–360): 357–360. doi:10.1016/j.brainresbull.2005.02.001. PMID 16144614. S2CID 14822113.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  20. ^ a b c d Marten, K. (2000). "Ultrasonic analysis of pygmy sperm whale (Kogia breviceps) and Hubbs' beaked whale (Mesoplodon carlhubbsi) clicks" (PDF). Aquatic Mammals. 26 (1): 45–48.
  21. ^ Huckstadt, L.A. & Antezana, T. (2001). "An observation of parturition in a stranded Kogia breviceps". Marine Mammal Science. 17 (2): 362–365. doi:10.1111/j.1748-7692.2001.tb01277.x.
  22. ^ Culik, Boris M. (2011). Odontocetes - The Toothed Whales (PDF). Bonn, Germany: CMS. pp. 74–76. ISBN 978-3-937429-92-2. Retrieved 27 January 2022.
  23. ^ Flood, Robert. "Pygmy Sperm Whale, breaching, from Cadiz to Lanzarote ferry, North Atlantic, 5th September 2018". YouTube. Retrieved 27 January 2022.
  24. ^ Willis, P.M. & Baird, R.W. (1998). "Status of the dwarf sperm whale, Kogia simus, with special reference to Canada". Canadian Field-Naturalist. 112 (1): 114–125.
  25. ^ Lundrigan, Barbara; Myers, Allison (2002-09-04). "Kogia breviceps (pygmy sperm whale)". Animal Diversity Web. Retrieved 2021-12-08.
  26. ^ Thomas, J.A.; et al. (1990). "A new sound from a stranded pygmy sperm whale" (PDF). Aquatic Mammals. 16 (1): 28–30.
  27. ^ a b Beatson, Emma (21 April 2007). "The diet of pygmy perm whales, Kogia breviceps, stranded in New Zealand: implications for conservation". Rev Fish Biol Fisheries. 10 (1007).
  28. ^ Long, D.J. (1991). "Apparent predation by a white shark Carcharadon charcharias on a pygmy sperm whale Kogia breviceps" (PDF). Fishery Bulletin. 89 (3): 538–540.
  29. ^ Dunphy-Daly, M.M.; et al. (2008). "Temporal variation in dwarf sperm whale (Kogia sima) habitat use and group size off Great Abaco Island, Bahamas". Marine Mammal Science. 24 (1): 171–182. doi:10.1111/j.1748-7692.2007.00183.x.
  30. ^ . NOAA Fisheries Office of Protected Resources web site. NOAA. 2014-10-20. Archived from the original on 2013-10-03. Retrieved 2015-01-11.
  31. ^ ХОРОШИЕ НОВОСТИ ПРО ЖИВОТНЫХ. 2017. НА КУНАШИРЕ (КУРИЛЫ) СПАСЛИ ЗАСТРЯВШЕГО НА МЕЛИ РЕДКОГО КАШАЛОТА С ДЕТЕНЫШЕМ. Retrieved on September 26, 2017
  32. ^ 2017. НА КУНАШИРЕ (КУРИЛЫ) СПАСЛИ ЗАСТРЯВШЕГО НА МЕЛИ РЕДКОГО КАШАЛОТА С ДЕТЕНЫШЕМ. Retrieved on September 26, 2017
  33. ^ Davis, R.W.; et al. (1998). "Physical habitat of cetaceans along the continental slope in the north-central and western Gulf of Mexico". Marine Mammal Science. 14 (3): 490–607. doi:10.1111/j.1748-7692.1998.tb00738.x.
  34. ^ Davis, Lance E.; Gallman, Robert E.; Gleiter, Karin (January 1997). In Pursuit of Leviathan: Technology, Institutions, Productivity, and Profits in American Whaling, 1816-1906. University of Chicago Press. pp. 20–56. ISBN 978-0-226-13789-6.
  35. ^ Davis, Lance E.; Gallman, Robert E.; Gleiter, Karin (January 1997). In Pursuit of Leviathan: Technology, Institutions, Productivity, and Profits in American Whaling, 1816-1906. University of Chicago Press. pp. 20–56. ISBN 978-0-226-13789-6.
  36. ^ a b c d Willis, P. M.; Baird, R. W. (1998). "Status of the dwarf sperm whale, Kogia simus, with special reference to Canada". Canadian Field-Naturalist. 112 (1): 114–125.
  37. ^ Loranger, Linda (3 December 1991). "Pygmy Sperm Whale Dies In Mystic After Record Time In Captivity". Hartford Courant. Retrieved 22 September 2016.
  38. ^ Klingener, Nancy (2 November 2000). "Pygmy Whale Snags Fence, Dies After Four Months In Captivity". Sun Sentinel. Retrieved 22 September 2016.
  39. ^ Manire, C.A.; et al. (2004). "An approach to the rehabilitation of Kogia spp". Aquatic Mammals. 30 (2): 257–270. doi:10.1578/AM.30.2.2004.257.
  40. ^ Official website of the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas
  41. ^ Official website of the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area
  42. ^ Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia
  43. ^ Official webpage of the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region
  44. ^ a b Scott, Michael D.; Campbell, Walton B.; Whitaker, Brent R.; Nicolas, John R.; Westgate, Andrew J.; Hohn, Aleta A. (January 2001). "A note on the release and tracking of a rehabilitated pygmy sperm whale (Kogia breviceps)". Journal of Cetacean Research and Management. 3 (1): 87–94.

Further reading

  • Pygmy and Dwarf Sperm Whales by Donald F. McAlpine in Encyclopedia of Marine Mammals pp. 1007–1009 ISBN 978-0-12-551340-1
  • 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

 
Wikispecies has information related to Kogia breviceps.
 
Wikimedia Commons has media related to Kogia breviceps.
  • UMMZ Skull photos
  • Photo of skull
  • Max Newman's Pygmy Sperm Whale Research Paper
  • dolphin rescues Pygmy Sperm whales
  • Voices in the Sea - Sounds of the Pygmy sperm Whale

August 18, 2023
pygmy, sperm, whale, pygmy, sperm, whale, kogia, breviceps, extant, species, family, kogiidae, sperm, whale, superfamily, they, often, sighted, most, what, known, about, them, comes, from, examination, stranded, specimens, individual, washed, ashore, hutchinso. The pygmy sperm whale Kogia breviceps is one of two extant species in the family Kogiidae in the sperm whale superfamily They are not often sighted at sea and most of what is known about them comes from the examination of stranded specimens Pygmy sperm whale 1 Individual washed ashore on Hutchinson Island FloridaSize compared to an average humanConservation statusLeast Concern IUCN 3 1 2 CITES Appendix II CITES 3 Scientific classificationDomain EukaryotaKingdom AnimaliaPhylum ChordataClass MammaliaOrder ArtiodactylaInfraorder CetaceaFamily KogiidaeGenus KogiaSpecies K brevicepsBinomial nameKogia breviceps Blainville 1838 Pygmy sperm whale rangeSynonymsPhyseter breviceps Contents 1 Taxonomy 2 Description 3 Anatomy 3 1 Teeth 3 2 Melon 3 3 Stomach 3 4 Brain 4 Echolocation 5 Reproduction 6 Behaviour 6 1 Diet foraging behavior 7 Population and distribution 8 Human interaction 9 Conservation 10 Specimens 11 See also 12 References 13 Further reading 14 External linksTaxonomy Edit Illustration from the 19th centuryThe pygmy sperm whale was first described by naturalist Henri Marie Ducrotay de Blainville in 1838 He based this on the head of an individual washed up on the coasts of Audierne in France in 1784 which was then stored in the Museum d histoire naturelle He recognized it as a type of sperm whale and assigned it to the same genus as the sperm whale Physeter macrocephalus as Physeter breviceps He noted its small size and nicknamed it cachalot a tete courte small headed sperm whale further the species name breviceps is Latin for short headed 4 In 1846 zoologist John Edward Gray erected the genus Kogia for the pygmy sperm whale as Kogia breviceps and said it was intermediate between the sperm whale and dolphins 5 In 1871 mammalogist Theodore Gill assigned it and Euphysetes now the dwarf sperm whale Kogia sima to the subfamily Kogiinae and the sperm whale to the subfamily Physeterinae 6 Both have now been elevated to the family level In 1878 naturalist James Hector synonymized the dwarf sperm whale with the pygmy sperm whale with both being referred to as K breviceps until 1998 7 Description Edit Pygmy sperm whale skeletonThe pygmy sperm whale is not much larger than many dolphins They are about 1 2 m 3 ft 11 in at birth growing to about 3 5 m 11 ft at maturity Adults weigh about 400 kg 880 lb The underside is a creamy occasionally pinkish colour and the back and sides are a bluish grey however considerable intermixing occurs between the two colours The shark like head is large in comparison to body size given an almost swollen appearance when viewed from the side A whitish marking often described as a false gill is seen behind each eye 8 9 The lower jaw is very small and slung low 10 The blowhole is displaced slightly to the left when viewed from above facing forward 10 The dorsal fin is very small and hooked its size is considerably smaller than that of the dwarf sperm whale and may be used for diagnostic purposes 10 Anatomy Edit Closeup of the headLike its giant relative the sperm whale the pygmy sperm whale has a spermaceti organ in its forehead see sperm whale for a discussion of its purpose It also has a sac in its intestines that contains a dark red fluid The whale may expel this fluid when frightened perhaps to confuse and disorient predators 11 Dwarf and pygmy sperm whales possess the shortest rostrum of current day cetaceans with a skull that is greatly asymmetrical 12 Pygmy sperm whales have from 50 to 55 vertebrae and from 12 to 14 ribs on either side although the latter are not necessarily symmetrical and the hindmost ribs do not connect with the vertebral column Each of the flippers has seven carpals and a variable number of phalanges in the digits reportedly ranging from two in the first digit to as many as 10 in the second digit No true innominate bone exists it is replaced by a sheet of dense connective tissue The hyoid bone is unusually large and presumably has a role in the whale s suction feeding 9 Pygmy sperm whale skull viewed from the side Teeth Edit The pygmy sperm has between 20 and 32 teeth all of which are set into the rostral part of the lower jaw 13 Unusually adults lack enamel due to a mutation in the enamelysin gene 14 although enamel is present in very young individuals 9 Pygmy whale teeth on its lower rostrumMelon Edit Like other toothed whales the pygmy sperm whale has a melon a body of fat and wax in the head that it uses to focus and modulate the sounds it makes 15 The inner core of the melon has a higher wax content than the outer cortex The inner core transmits sound more slowly than the outer layer allowing it to refract sound into a highly directional beam 16 Behind the melon separated by a thin membrane is the spermaceti organ Both the melon and the spermaceti organ are encased in a thick fibrous coat resembling a bursa 17 The whale produces sound by moving air through the right nasal cavity which includes a valvular structure or museau de singe with a thickened vocal reed functioning like the vocal cords of humans Stomach Edit The stomach has three chambers The first chamber or forestomach is not glandular and opens directly into the second fundic chamber which is lined by digestive glands A narrow tube runs from the second to the third or pyloric stomach which is also glandular and connects via a sphincter to the duodenum Although fermentation of food material apparently occurs in the small intestine no caecum is present 18 Brain Edit The rostroventral dura of the brain contains a significant concentration of magnetite crystals which suggests that K breviceps can navigate by magnetoreception 9 Studies have also shown that compared to the sperm whale the pygmy sperm whale brain has significantly fewer neurons which may be connected to a decreased complexity in social interaction and group based living 19 Echolocation EditLike all toothed whales the pygmy sperm whale hunts prey by echolocation Sound produced for echolocation by many odontocetes come in the form of high frequency clicks 20 The frequencies it uses are mostly ultrasonic 16 peaking around 125 kHz 20 The clicks from their echolocation has been recorded to last an average of 600 microseconds When closing in on prey the click repetition rate starts at 20 Hz and then begins to rise when nearing the target 20 The pulse sounds that pygmy sperm whales make for echolocation are generated primarily from the museau de singe or monkey s muzzle which is an anatomical structure located within the whale s skull that produces sound when air passes through its lips 16 The sound from the museau de singe is transferred to the attached cone of the spermaceti organ Unique from other odontocetes the spermaceti organ contacts the posterior of the whale s melon 16 Fat from the core of the spermaceti organ helps direct sonic energy from the museau de singe to the melon 16 The melon acts as a sonic magnifier and gives directionality to sound pulses making echolocation more efficient Fat on the interior of the melon has a lower molecular weight lipid than the surrounding outer melon 16 Since the sound waves move from a lower velocity material to a higher one during sound production the sound undergoes inward refraction and becomes increasingly focused Variation in fat density within the melon ultimately contributes to the production of highly directional ultrasonic sound beams in front of the melon The combined melon and spermaceti organ system cooperate to focus echolocative sounds Like in most odontocetes the known echoreception apparatus used by the pygmy sperm whale is linked to the fat filled lower mandibles within the skull 16 However compositional topography of the pygmy sperm whale s skull indicates abnormally large fatty jowls surrounding the mandibles suggesting a more intricate echoreception apparatus 16 Additionally an unusual cushion structure of porous and spongy texture found behind the museau de singe has been hypothesized of being a possible pressure receptor 16 The positioning of this cushion structure in close proximity to the largest cavities closest to the museau de singe may suggest that it is a sound absorber used for echoreception Reproduction EditSee also Whale reproduction Although firm details concerning pygmy sperm whale reproduction are limited they are believed to mate from April to September in the Southern Hemisphere and March to August in the Northern Hemisphere 9 These whales become sexually mature at age 4 5 and like virtually all mammals are iteroparous reproducing many times during their lives Once a female whale is impregnated the average gestation period lasts 9 11 months and unusually for cetaceans the female gives birth to a single calf head first 21 Newborn calves are about 1 2 metres 3 ft 11 in in length weighing 50 kg and are weaned around one year of age 9 They are believed to live up to age 23 Behaviour EditThe whale makes very inconspicuous movements It rises to the surface slowly with little splash or blow and remains there motionless for some time In Japan the whale was historically known as the floating whale because of this Its dive is equally lacking in grand flourish it simply drops out of view The species has a tendency to back away from rather than approach boats Breaching has been observed but is not common 22 23 Pygmy sperm whales are normally either solitary or found in pairs 24 but have been seen in groups up to six 25 Dives have been estimated to last an average of 11 minutes although longer dives up to 45 minutes have been reported 9 The ultrasonic clicks of pygmy sperm whales range from 60 to 200 kHz peaking at 125 kHz 20 and the animals also make much lower frequency cries at 1 to 2 kHz 26 Diet foraging behavior Edit Analysis of stomach contents suggests that pygmy sperm whales feed primarily on cephalopods most commonly including bioluminescent species found in midwater environments Most of the cephalopod hunting is known to be pelagic and fairly shallow within the first 100 m of the surface 27 The most common prey are reported to include glass squid and lycoteuthid and ommastrephid squid although the whales also consume other squid and octopuses They have also been reported to eat some deep sea shrimps but compared with dwarf sperm whales relatively few fish 9 Predators may include great white sharks 28 and killer whales 29 Pygmy sperm whales and dwarf 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 tracts that contains up to 12 liters of dark reddish brown fluid which can be ejected to confuse or discourage potential predators 30 Population and distribution EditPygmy sperm whales are found throughout the tropical and temperate waters of the Atlantic Pacific and Indian Oceans 9 and occasionally among colder waters such as off Russia 31 32 However they are rarely sighted at sea so most data come from stranded animals making a precise range and migration map difficult They are believed to prefer off shore waters and are most frequently sighted in waters ranging from 400 to 1 000 m 1 300 to 3 300 ft in depth especially where upwelling water produces local concentrations of zooplankton and animal prey 33 Their status is usually described as rare but occasional patches of higher density strandings suggest they might be more common than previously estimated The total population is unknown Fossils identified as belonging to K breviceps have been recovered from Miocene deposits in Italy Japan and southern Africa 9 Human interaction EditPygmy sperm whales have never been hunted on a wide scale Land based whalers have hunted them from Indonesia Japan and the Lesser Antilles This species was impacted by whaling in the 18th and 19th centuries as sperm whales were especially sought after by whalers for their sperm oil produced by the spermaceti organ The oil was used to fuel kerosene lamps Ambergris a waste product produced by the whales was also valuable to whalers as it was used by humans in cosmetics and perfume 34 They were not as heavily hunted as their larger counterpart Physeter macrocephalus the sperm whale which are typically 120 000 lb thus preferred by whalers 35 The pygmy sperm whale is also rather inactive and slow rising when coming to the surface and as such do not bring much attention to themselves However they were easy targets as they tended to swim slowly and lie motionless at the surface 36 Individuals have also been recorded killed in drift nets Some stranded animals have been found with plastic bags in their stomachs which may be a cause for concern Whether these activities are causing long term damage to the survival of the species is not known Pygmy sperm whales do not do well in captivity 37 38 The longest recorded survival in captivity is 21 months and most captive individuals die within one month mostly due to dehydration or dietary problems 39 Pygmy sperm whales have been reported as being forced to change their diets and foraging behaviors due to anthropological factors such as deep sea trawling and increased fishing for cephalopods off the coast of many Southeast Asian countries 27 Conservation EditIn 1985 the International Whaling Commission ended sperm whaling 36 The pygmy sperm whale is covered by the Agreement on the Conservation of Small Cetaceans of the Baltic North East Atlantic Irish and North Seas ASCOBANS 40 and the Agreement on the Conservation of Cetaceans in the Black Sea Mediterranean Sea and Contiguous Atlantic Area ACCOBAMS 41 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 42 and the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region Pacific Cetaceans MoU 43 As not much is known about this species as well as due to the whaling and conservation laws in place for marine mammals it is listed as lower risk least concern in the IUCN Red list 36 However it faces some modern day issues it is one of the most common stranded species in Florida sound Due to its slow moving and quiet nature the species is at a higher risk of boat strikes 44 Its small size also allows for it to become a byproduct of commercial fishing caught in seine nets 36 Anthropogenic noise caused by military activity and shipping is another issue affecting this species as it echolocates Pygmy sperm whales have also repeatedly been found stranded with plastic in their stomachs 44 Specimens EditMNZ MM002651 collected Hawke s Bay New Zealand no date dataSee also Edit Cetaceans portal Mammals portal Marine life portalCetacean Conservation Center List of cetaceans Marine biology Whale oilReferences Edit Mead J G Brownell R L Jr 2005 Order Cetacea In Wilson D E Reeder D M eds Mammal Species of the World A Taxonomic and Geographic Reference 3rd ed Johns Hopkins University Press p 737 ISBN 978 0 8018 8221 0 OCLC 62265494 Kiszka J Braulik G 2020 Kogia breviceps IUCN Red List of Threatened Species 2020 e T11047A50358334 doi 10 2305 IUCN UK 2020 2 RLTS T11047A50358334 en Retrieved 19 November 2021 Appendices CITES cites org Retrieved 2022 01 14 de Blainville M H 1838 Sur les Cachalot On the Sperm Whales Annales Francaises et Etrangeres d Anatomie et de Physiologie in French 2 335 337 Gray J E 1846 Zoology of the Voyage of H M S Erebus amp Terror Under the Command of Captain Sir James Clark Ross R N F R S During the Years 1839 to 1843 Mammalia 1 22 Gill T 1871 The Sperm Whales Giant and Pygmy American Naturalist 4 12 725 743 doi 10 1086 270684 Rice D W 1998 Marine Mammals of the World Systematics and Distribution PDF Society for Marine Mammalogy pp 83 84 ISBN 978 1 891276 03 3 Roest A I 1970 Kogia simus and other cetaceans from San Luis Obispo County California Journal of Mammalogy 51 2 410 417 doi 10 2307 1378507 JSTOR 1378507 a b c d e f g h i j Bloodworth B E amp Odell D K 2008 Kogia breviceps Cetacea Kogiidae Mammalian Species 819 Number 819 pp 1 12 doi 10 1644 819 1 a b c Pygmy Sperm Whale www acsonline org Retrieved 2022 04 06 Scott M D amp Cordaro J G 1987 Behavioral observations of the dwarf sperm whale Kogia simus Marine Mammal Science 3 4 353 354 doi 10 1111 j 1748 7692 1987 tb00322 x Mcalpine Donald F Pygmy and dwarf sperm whales Kogia breviceps and K sima Encyclopedia of Marine Mammals Second Edition 2009 936 938 Bloodworth Brian E Odell Daniel K 2008 Kogia breviceps Mammalian Species 819 1 12 doi 10 1644 819 1 Meredith R W Gatesy J Cheng J Springer M S 2010 Pseudogenization of the tooth gene enamelysin MMP20 in the common ancestor of extant baleen whales Proceedings of the Royal Society B Biological Sciences 278 1708 993 1002 doi 10 1098 rspb 2010 1280 PMC 3049022 PMID 20861053 Clarke M R 2003 Production and control of sound by the small sperm whale Kogia breviceps and K sima and their implications for other Cetacea Journal of the Marine Biological Association of the United Kingdom 83 2 241 263 doi 10 1017 S0025315403007045h S2CID 84103043 a b c d e f g h i R Karol C Litchfield D Caldwell M Caldwell 1978 Compositional topography of melon and spermaceti organ lipids in the pygmy sperm whale Kogia breviceps Implications for echolocation Marine Biology Volume 47 2 Cranford T W et al 1996 Functional morphology and homology in the odontocete nasal complex implications for sound generation Journal of Morphology 228 2 223 285 doi 10 1002 SICI 1097 4687 199606 228 3 lt 223 AID JMOR1 gt 3 0 CO 2 3 PMID 8622183 S2CID 35653583 Hagey L R et al 1993 Biliary bile acid composition of the Physeteridae sperm whales Marine Mammal Science 9 1 23 33 doi 10 1111 j 1748 7692 1993 tb00423 x Poth Fung Gunturkun Ridgway 2005 02 25 Neuron numbers in sensory corticies of five delphinids compared to a physterid the pygmy perm whale Brain Research Bulletin 66 357 360 357 360 doi 10 1016 j brainresbull 2005 02 001 PMID 16144614 S2CID 14822113 a href Template Cite journal html title Template Cite journal cite journal a CS1 maint multiple names authors list link a b c d Marten K 2000 Ultrasonic analysis of pygmy sperm whale Kogia breviceps and Hubbs beaked whale Mesoplodon carlhubbsi clicks PDF Aquatic Mammals 26 1 45 48 Huckstadt L A amp Antezana T 2001 An observation of parturition in a stranded Kogia breviceps Marine Mammal Science 17 2 362 365 doi 10 1111 j 1748 7692 2001 tb01277 x Culik Boris M 2011 Odontocetes The Toothed Whales PDF Bonn Germany CMS pp 74 76 ISBN 978 3 937429 92 2 Retrieved 27 January 2022 Flood Robert Pygmy Sperm Whale breaching from Cadiz to Lanzarote ferry North Atlantic 5th September 2018 YouTube Retrieved 27 January 2022 Willis P M amp Baird R W 1998 Status of the dwarf sperm whale Kogia simus with special reference to Canada Canadian Field Naturalist 112 1 114 125 Lundrigan Barbara Myers Allison 2002 09 04 Kogia breviceps pygmy sperm whale Animal Diversity Web Retrieved 2021 12 08 Thomas J A et al 1990 A new sound from a stranded pygmy sperm whale PDF Aquatic Mammals 16 1 28 30 a b Beatson Emma 21 April 2007 The diet of pygmy perm whales Kogia breviceps stranded in New Zealand implications for conservation Rev Fish Biol Fisheries 10 1007 Long D J 1991 Apparent predation by a white shark Carcharadon charcharias on a pygmy sperm whale Kogia breviceps PDF Fishery Bulletin 89 3 538 540 Dunphy Daly M M et al 2008 Temporal variation in dwarf sperm whale Kogia sima habitat use and group size off Great Abaco Island Bahamas Marine Mammal Science 24 1 171 182 doi 10 1111 j 1748 7692 2007 00183 x Pygmy sperm whale Kogia breviceps NOAA Fisheries Office of Protected Resources web site NOAA 2014 10 20 Archived from the original on 2013 10 03 Retrieved 2015 01 11 HOROShIE NOVOSTI PRO ZhIVOTNYH 2017 NA KUNAShIRE KURILY SPASLI ZASTRYaVShEGO NA MELI REDKOGO KAShALOTA S DETENYShEM Retrieved on September 26 2017 2017 NA KUNAShIRE KURILY SPASLI ZASTRYaVShEGO NA MELI REDKOGO KAShALOTA S DETENYShEM Retrieved on September 26 2017 Davis R W et al 1998 Physical habitat of cetaceans along the continental slope in the north central and western Gulf of Mexico Marine Mammal Science 14 3 490 607 doi 10 1111 j 1748 7692 1998 tb00738 x Davis Lance E Gallman Robert E Gleiter Karin January 1997 In Pursuit of Leviathan Technology Institutions Productivity and Profits in American Whaling 1816 1906 University of Chicago Press pp 20 56 ISBN 978 0 226 13789 6 Davis Lance E Gallman Robert E Gleiter Karin January 1997 In Pursuit of Leviathan Technology Institutions Productivity and Profits in American Whaling 1816 1906 University of Chicago Press pp 20 56 ISBN 978 0 226 13789 6 a b c d Willis P M Baird R W 1998 Status of the dwarf sperm whale Kogia simus with special reference to Canada Canadian Field Naturalist 112 1 114 125 Loranger Linda 3 December 1991 Pygmy Sperm Whale Dies In Mystic After Record Time In Captivity Hartford Courant Retrieved 22 September 2016 Klingener Nancy 2 November 2000 Pygmy Whale Snags Fence Dies After Four Months In Captivity Sun Sentinel Retrieved 22 September 2016 Manire C A et al 2004 An approach to the rehabilitation of Kogia spp Aquatic Mammals 30 2 257 270 doi 10 1578 AM 30 2 2004 257 Official website of the Agreement on the Conservation of Small Cetaceans of the Baltic North East Atlantic Irish and North Seas 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 a b Scott Michael D Campbell Walton B Whitaker Brent R Nicolas John R Westgate Andrew J Hohn Aleta A January 2001 A note on the release and tracking of a rehabilitated pygmy sperm whale Kogia breviceps Journal of Cetacean Research and Management 3 1 87 94 Further reading EditPygmy and Dwarf Sperm Whales by Donald F McAlpine in Encyclopedia of Marine Mammals pp 1007 1009 ISBN 978 0 12 551340 1 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 0External links Edit Wikispecies has information related to Kogia breviceps Wikimedia Commons has media related to Kogia breviceps UMMZ Skull photos 1 Photo of skull Max Newman s Pygmy Sperm Whale Research Paper dolphin rescues Pygmy Sperm whales Arkive Voices in the Sea Sounds of the Pygmy sperm Whale Retrieved from https en wikipedia org w index php title Pygmy sperm whale amp oldid 1168575187, wikipedia, wiki, book, books, library,

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