The dwarf sperm whale (''Kogia sima'') is a
sperm whale
The sperm whale or cachalot (''Physeter macrocephalus'') is the largest of the toothed whales and the largest toothed predator. It is the only living member of the genus ''Physeter'' and one of three extant species in the sperm whale famil ...
that inhabits temperate and tropical oceans worldwide, in particular continental
shelves and
slopes. It was first
described by
biologist
A biologist is a scientist who conducts research in biology. Biologists are interested in studying life on Earth, whether it is an individual cell, a multicellular organism, or a community of interacting populations. They usually specialize in ...
Richard Owen
Sir Richard Owen (20 July 1804 – 18 December 1892) was an English biologist, comparative anatomist and paleontologist. Owen is generally considered to have been an outstanding naturalist with a remarkable gift for interpreting fossils.
Owe ...
in 1866, based on illustrations by
naturalist Sir Walter Elliot. The species was considered to be
synonymous
A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...
with the
pygmy sperm whale (''Kogia breviceps'') from 1878 until 1998. The dwarf sperm whale is a small whale, and , that has a grey coloration, square head, small jaw, and robust body. Its appearance is very similar to the pygmy sperm whale, distinguished mainly by the position of the
dorsal fin on the body–nearer the middle in the dwarf sperm whale and nearer the tail in the other.
The dwarf sperm whale is a
suction feeder that mainly eats squid, and does this in small pods of typically one to four members. It is preyed upon by the
killer whale (''Orcinus orca'') and large sharks such as the
great white shark (''Carcharodon carcharius''). When startled, the whale can eject a cloud of red-brown fluid. Most of what is known of the whale comes from
beached individuals, as sightings in the ocean are rare. Many of these stranded whales died from parasitic infestations or
heart failure
Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, a ...
.
The dwarf sperm whale is hunted in small numbers around Asia. It is most threatened by ingesting, or getting
entangled by,
marine debris
Marine debris, also known as marine litter, is human-created waste that has deliberately or accidentally been released in a sea or ocean. Floating oceanic debris tends to accumulate at the center of gyres and on coastlines, frequently washing ...
. No global population estimate has been made, and so its
conservation status by the
International Union for Conservation of Nature (IUCN) is least concern.
Taxonomy

The first two dwarf sperm whale
specimen
Specimen may refer to:
Science and technology
* Sample (material), a limited quantity of something which is intended to be similar to and represent a larger amount
* Biological specimen or biospecimen, an organic specimen held by a biorepository ...
s, a male and a female, were collected in 1853 by
naturalist Sir Walter Elliot, who thought it a kind of
porpoise
Porpoises are a group of fully aquatic marine mammals, all of which are classified under the family Phocoenidae, parvorder Odontoceti (toothed whales). Although similar in appearance to dolphins, they are more closely related to narwhals an ...
due to the short snout. However, when he sent drawings of these whales – including skeletal diagrams – to biologist Richard Owen to describe, Owen, in his 1866 paper, recognized it as a type of sperm whale in the family
Physeteridae based on several similar characteristics, such as having functional teeth in only the lower jaw, a lopsided blowhole leaning towards the left side, and a
spermaceti organ
The spermaceti organ is an organ present in the heads of toothed whales of the family Physeteroidea, in particular the sperm whale. This organ contains a waxy liquid called spermaceti and is involved in the generation of sound.
Description
In ...
. He named it ''Physeter (Euphysetes) simus'', the same genus as the
sperm whale
The sperm whale or cachalot (''Physeter macrocephalus'') is the largest of the toothed whales and the largest toothed predator. It is the only living member of the genus ''Physeter'' and one of three extant species in the sperm whale famil ...
(''Physeter macrocephalus'') and the
pygmy sperm whale (now ''Kogia breviceps''), with ''Euphysetes'' acting as a
subgenus
In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus.
In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...
.
The
species name ''simus'' is
Latin for "stump-nosed", a reference to its blunt snout.
John Edward Gray, when he created the genus ''
Kogia
''Kogia'' is a genus of toothed whales within the superfamily Physeteroidea comprising two extant and two extinct species from the Neogene
*Pygmy sperm whale, ''Kogia breviceps''
*Dwarf sperm whale, ''Kogia sima''
*†'' Kogia pusilla'', Italy, ...
'' in 1846, gave no indication to the meaning, but, since the word has a
feminine ending, the masculine species name ''simus'' had to be changed to ''sima'' to fit this when the combination ''Kogia simus'' was proposed by various 20th century authors.
In 1900, zoologist
Frank Evers Beddard
Frank Evers Beddard FRS FRSE (19 June 1858 – 14 July 1925) was an English zoologist. He became a leading authority on annelids, including earthworms. He won the Linnean Medal in 1916 for his book on oligochaetes.
Life
Beddard was born in ...
speculated that the word "might be a tribute to a Turk of the past surnamed Cogia Effendi, who observed whales in the Mediterranean".
In 1871,
mammalogist Theodore Gill split Physeteridae into two subfamilies: Physterinae with ''Physeter'', and Kogiinae with ''Kogia'' and the now-defunct ''Euphysetes''; this has now been elevated to family,
Kogiidae
Kogiidae is a family comprising at least two extant species of Cetacea, the Pygmy sperm whale, pygmy (''Kogia breviceps)'' and dwarf sperm whale, dwarf (''K. sima)'' sperm whales. As their common names suggest, they somewhat resemble sperm whales ...
.
Gill also proposed the dwarf sperm whale be moved to its own genus, ''Calignathus''. In 1878, naturalist
James Hector synonymized the dwarf sperm whale with the pygmy sperm whales as ''K. breviceps''. No distinction was made by most authors until mammalogist Dale Rice in his 1998 review of marine mammal taxonomy citing the works of Dr. Teizo Ogawa from 1936, researcher Munesato Yamada from 1954,
zoologist Charles Handley from 1966, and
mammalogist Graham James Berry Ross from 1979.
Genetic testing in 2006 suggests that ''K. sima'' may actually represent two species, one in the Atlantic and one in the Indo-Pacific region. The
Cape of Good Hope
The Cape of Good Hope ( af, Kaap die Goeie Hoop ) ;''Kaap'' in isolation: pt, Cabo da Boa Esperança is a rocky headland on the Atlantic coast of the Cape Peninsula in South Africa.
A common misconception is that the Cape of Good Hope is t ...
around South Africa may mark the barrier between these two populations.
[
]
Description
The dwarf sperm whale can range in size from in length and in weight—less than the and pygmy sperm whale. A newborn is generally around long and . Males are thought to reach physical maturity at age 15, and females at age 13. Sexual maturity, which happens after an individual has attained in length, happens at 2 to 3 years for males and around 5 for females. Gestation takes place probably over around 9.5 months.
The dwarf sperm whale has a dark-grey or blue-grey coloration with a lighter-grey underside, and a pale, crescent-shaped mark between the eye and the flipper, sometimes called a "fake gill", which is characteristic of the genus. Some individuals have been known to have a second crescent-shaped mark, creating a sort of pale ring encircling a darker spot. It has a high dorsal fin halfway down the length of the body, and two or more throat grooves. The dorsal fin is taller and closer to the head than it is in the pygmy sperm whale, and the back is flatter.
''Kogia'' is identified as having a square head, a small jaw with the snout jutting outward, and a porpoise-like build with a robust body that rapidly decreases towards the tail. They have the shortest snouts of any modern day whale. Characteristic of sperm whales, the left nostril is markedly larger than the right, and it has a spermaceti organ on its skull. The brain weighs around . The eyes are adapted for low-light environments. The dwarf sperm whale has 14 to 24 teeth, rarely 26, in the lower jaw that are sharp, slightly curved backwards, and–like other sperm whales–lack enamel. The teeth rarely exceed in length, smaller than those of the pygmy sperm whale. At most, 6 teeth are in the upper jaws, though in modern sperm whales, upper teeth are defunct.
Unique to ''Kogia'', there is a sac which hangs off from the small intestine
The small intestine or small bowel is an organ in the gastrointestinal tract where most of the absorption of nutrients from food takes place. It lies between the stomach and large intestine, and receives bile and pancreatic juice through the p ...
s near the anus
The anus (Latin, 'ring' or 'circle') is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, the residual semi-solid waste that remains after food digestion, which, d ...
that is filled with a dense, red-brown fluid that looks similar to chocolate syrup. When stressed, this fluid is released. The dwarf sperm whale has between 50 and 57 vertebrae, 7 neck vertebra
In tetrapods, cervical vertebrae (singular: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In ...
e, 12 to 14 thoracic vertebrae, and 29 or 35-to-37 lumbar vertebrae. The variation can either be due to loss of bones during preparation of a specimen, or individual variations. It is not known to be sexually dimorphic.
Population and distribution
The dwarf sperm whale ranges throughout tropical and temperate oceans of the world and inhabits the continental shelf
Shelf ( : shelves) may refer to:
* Shelf (storage), a flat horizontal surface used for display and storage
Geology
* Continental shelf, the extended perimeter of a continent, usually covered by shallow seas
* Ice shelf, a thick platform of ice f ...
and slope area. It seems to prefer warmer waters than the pygmy sperm whale. The dwarf sperm whale is one of the most commonly beached deep-diving whales in the world, though rarely seen at sea, and likewise, most information about the whale comes from examining beached individuals. Diving depth may vary from place to place: a study in the Bahamas placed average depth at around , whereas a study in the deeper waters of Hawaii placed it at around .
In the West Pacific, its recorded range spans from Japan to Tasmania and New Zealand, and in the East Pacific from British Columbia to central Chile. In the Indian Ocean, the whale is reported from Oman, Sri Lanka, India, Thailand, Philippines, Indonesia around Timor, western Australia and South Africa. In the West Atlantic, it has been recorded from Virginia to southern Brazil, and in the East Atlantic from Italy in the Mediterranean Sea to South Africa.
No global population estimation has been made. Population counts have been taken over certain areas, though given the difficulty to distinguish the dwarf sperm whale from the pygmy sperm whale, the overall estimate represents the total number of both species. In the North Atlantic, they are estimated at around 3,785 individuals; in the East Pacific, around 11,200 individuals.
Ecology
Diet
The dwarf sperm whale is an open ocean predator. The stomach contents of stranded dwarf sperm whales comprise mainly squid and, to a lesser degree, deep sea fish
Deep-sea fish are fish that live in the darkness below the sunlit surface waters, that is below the epipelagic or photic zone of the sea. The lanternfish is, by far, the most common deep-sea fish. Other deep sea fishes include the flashlight ...
(from the mesopelagic and bathypelagic
The bathypelagic zone or bathyal zone (from Greek βαθύς (bathýs), deep) is the part of the open ocean that extends from a depth of below the ocean surface. It lies between the mesopelagic above, and the abyssopelagic below. The bathypelagic ...
zones) and crustaceans. However, crustaceans make up a sizable part of the diets of Hawaiian dwarf sperm whales, up to 15%. The stomach contents of whales washed up in different regions of the world indicate a preference for cock-eyed squid and glass squid across its range, particularly the elongate jewel squid
''Histioteuthis reversa'', commonly known as the reverse jewel squid or the elongate jewel squid, is a species of cock-eyed squid, so called because the eyes are dissimilar. It occurs at moderate depths in the Atlantic Ocean and Mediterranean Se ...
(''Histioteuthis reversa'') and '' Taonius''.
The throat grooves and the developed musculature in the throat in ''Kogia'' are probably adaptations for increasing the volume of the mouth for suction feeding, possibly the best-developed among toothed whales. Also, the blunt snout, lack of teeth, and reduced jaw are characteristics seen in other suction feeding toothed whales. The whale uses its sharp teeth to hold onto prey while expelling water from the mouth.
Dwarf sperm whale calves typically start eating solid food once they have reached a size of around though are not fully weaned until they reach around . Toothed whale calves generally start eating solid food at around 6 months, and mothers stop lactating after around 18 to 20 months.
Threats
Killer whales (''Orcinus orca'') and sharks are known to prey on the dwarf sperm whale.[ Dwarf sperm whale remains have been found in the stomachs of great white sharks (''Carcharodon carcharias''), and infestations of the ]cestode
Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, known as tapeworms. Their bodies consist of man ...
'' Phyllobothrium delphini'' in beached individuals indicates shark attacks since the cestode matures in sharks.
The dwarf sperm whale also competes with other squid-eating whales, such as beaked whale
Beaked whales (systematic name Ziphiidae) are a family of cetaceans noted as being one of the least known groups of mammals because of their deep-sea habitat and apparent low abundance. Only three or four of the 24 species are reasonably well-k ...
s. It occupies the same ecological niche in the same regions as the pygmy sperm whale, though the latter can forage in deeper waters and has been known to feed on a wider array of species of larger size.[
Some beached individuals have had large parasitic infestations which probably lead to their death, particular with ]nematode
The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...
s in the stomach and tapeworms in the blubber
Blubber is a thick layer of vascularized adipose tissue under the skin of all cetaceans, pinnipeds, penguins, and sirenians.
Description
Lipid-rich, collagen fiber-laced blubber comprises the hypodermis and covers the whole body, except for pa ...
. In the southeastern United States, stranded dwarf sperm whales were found to have died from heart failure
Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, a ...
, and heart failure may have led to the stranding itself.
Behavior
''Kogia'' is thought to be slow-moving, rarely displaying rapid surfacing behavior, tending to float at the surface with only the nape and dorsal fin exposed. From the surface, they sink vertically, instead of lifting their tails out of the water to dive, which would create a splash.
The dwarf sperm whale congregates into small pods of one to four individuals, though on occasion up to ten, likely due to limited food resources. Small group size and deep foraging grounds in the summer could also be anti-predator behaviors. However, this is less likely as dolphins congregate in large pods with hundreds of members to prevent predation. The whale probably follows seasonal squid migrations from offshore in the summer to nearshore in the winter. It is possible it prefers a slope habitat as it allows the whale to herd squid against the wall, or it causes upwelling which the whale can ride on in order to save energy while hunting. Younger animals may congregate in shallower areas and adults in deeper areas; the slope around South Africa may be a nursery grounds.
''Kogia'', unlike other whales, can eject a red-brown fluid when startled, likely to distract predators, similar to squid. This cloud can cover in the water.
This species does not whistle, and instead produces narrowband high- frequency clicks. These clicks are more similar to those produced by some dolphin and porpoise species–such as the hourglass dolphin (''Sagmatias cruciger''), Hector's dolphin (''Cephalorhynchus hectori''), the Chilean dolphin (''Cephalorhynchus eutropia''), Commerson's dolphin (''Cephalorhynchus commersonii''), the harbour porpoise (''Phocoena phocoena''), and Dall's porpoise (''Phocoenoides dalli'')–than to those of other deep-diving whales, such as beaked whales and the sperm whale. The peak frequencies
Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...
of ''Kogia'' are generally less than 130 kHz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that on ...
.
Relationship with humans
There is some hunting of the dwarf sperm whale in Indonesia, Japan, Sri Lanka, and the Lesser Antilles as food
Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is inge ...
or bait, though there are no major operations. A bigger threat is likely ingestion of marine debris
Marine debris, also known as marine litter, is human-created waste that has deliberately or accidentally been released in a sea or ocean. Floating oceanic debris tends to accumulate at the center of gyres and on coastlines, frequently washing ...
and entanglement in fishing gear, though it has not been determined how serious a threat these pose. The International Union for Conservation of Nature (IUCN) currently lists the dwarf sperm whale's conservation status as data deficient
A data deficient (DD) species is one which has been categorized by the International Union for Conservation of Nature (IUCN) as offering insufficient information for a proper assessment of conservation status to be made. This does not necessaril ...
, though it could possibly be of least concern.
The dwarf sperm whale is covered by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area. 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), and the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU).
See also
*''Kogia pusilla
''Kogia pusilla'' is an extinct species of sperm whale from the Middle Pliocene of Italy related to the modern day dwarf sperm whale (''K. sima'') and pygmy sperm whale (''K. breviceps''). It is known from a single skull discovered in 1877, a ...
''
* List of cetaceans
References
Further reading
* ''Whales Dolphins and Porpoises'', Mark Carwardine, Dorling Kindersley Handbooks,
* ''National Audubon Society Guide to Marine Mammals of the World'', Reeves, Stewart, Clapham and Powell,
External links
Whale & Dolphin Conservation Society (WDCS)
{{Taxonbar, from=Q42669
Sperm whales
Fauna of Southeast Asia
Cetaceans of the Indian Ocean
Cetaceans of the Pacific Ocean
Cetaceans of the Atlantic Ocean
Mammals described in 1866
Taxa named by Richard Owen