The
kitefin shark or
seal shark,
Dalatias licha, is a species of
dogfish sharkSqualiformes is an order of sharks that includes about 80 species in seven families.Members of the order have two dorsal fins, which usually possess spines, no anal fin or nictitating membrane, and five gill slits. In most other respects, however, they are quite variable in form and size...
in the family
DalatiidaeDalatiidae is a family of sharks in the order Squaliformes, commonly known as kitefin sharks . Members of this family are small, under long, and are found worldwide. They have cigar-shaped bodies with narrow heads and rounded snouts...
, and the only species in its
genusIn biology, a genus is a taxonomic unit used in the classification of living and fossil organisms. The term comes from Latin genus "descent, family, type, gender" , cognate with – genos, "race, stock, kin" ..In addition, genus is a taxonomic rank in the hierarchy In biology, a genus (plural:...
. It is found sporadically around the world, usually close to the sea floor at depths of 200–600 m (660–2,000 ft). With a sizable oil-filled liver to maintain
neutral buoyancyNeutral buoyancy is a condition in which a physical body's mass equals the mass it displaces in a surrounding medium. This offsets the force of gravity that would otherwise cause the object to sink...
, this shark is able to cruise slowly through the water while expending little energy. The kitefin shark has a slender body with a very short, blunt snout, large eyes, and thick lips. Its teeth are highly differentiated between the upper and lower jaws, with the upper teeth small and narrow and the lower teeth large, triangular, and serrated. Its typical length is 1.0–1.4 m (2.5–4.0 ft).
Armed with large teeth and a strong bite, the kitefin shark is a powerful, solitary predator that takes many different types of prey, ranging from bony fishes, sharks and rays, to
cephalopod{Taxobox| name = Cephalopods| fossil_range = | image = Tafel 054 300.jpg| image_caption = A variety of cephalopod forms from Ernst Haeckel's 1904 Kunstformen der Natur| regnum = Animalia| image_width = 220px| phylum = Mollusca| classis = Cephalopoda...
s,
crustaceanCrustaceans are a very large group of arthropods, comprising almost 52,000 described species , and are usually treated as a subphylum . They include various familiar animals, such as crabs, lobsters, crayfish, shrimp, krill and barnacles...
s, polychaete worms, siphonophores, and possibly
carrionCarrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters, or scavengers, include Hyenas, Vultures, Canadian Opossum, Tasmanian Devils, Black Bears, Komodo Dragons, Bald Eagles, Raccoons,...
. It also takes bites out of animals larger than itself, similar to its smaller relative, the
cookiecutter sharkThe cookiecutter shark, Isistius brasiliensis, also known as the cigar shark or luminous shark, is a small, rarely-seen dogfish shark.-Anatomy and morphology:...
(
Isistius brasiliensis). This shark is aplacental viviparous and gives birth to 10–14 young. The kitefin shark is
fished commerciallyCommercial fishing is the activity of capturing fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often pursue fish far into the ocean under adverse...
for its meat, skin, and liver oil, primarily by
PortugalPortugal , officially the Portuguese Republic , is a country located in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of mainland Europe and is bordered by the Atlantic Ocean to the west and south and by Spain to the north and east...
and
Japanis an island country in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, People's Republic of China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. A fishery targeting this species existed off the
AzoresThe Azores is a Portuguese archipelago in the Atlantic Ocean, about from Lisbon and about from the east coast of North America. The two westernmost Azorean islands actually lie on the North American plate...
from the 1970s to the 1990s, but collapsed due to
overfishingOverfishing occurs when fishing activities reduce fish stocks below an acceptable level. This can occur in any body of water from a pond to the oceans....
and falling liver oil prices; the rapid depletion of the Azores stock is often cited as an example of the susceptibility of deep-sea sharks to human exploitation. The International Union for Conservation of Nature (IUCN) does not yet have sufficient information to assess the global conservation status of this species beyond
Data DeficientData Deficient is a category applied by the IUCN to a species when the available information is not sufficient for a proper assessment of conservation status to be made. This does not necessarily indicate that the species has not been extensively studied; but it does indicate that little or no...
.
Taxonomy
The kitefin shark was originally described as
Squalus licha by French
naturalistNaturalist may refer to:* A scholar or student of natural history, the science of the natural world; see also natural science. It may also refer to a Wildlife enthusiast or a Conservationist....
Pierre Joseph BonnaterreAbbé Pierre Joseph Bonnaterre was a French naturalist who contributed sections on cetaceans, mammals, birds, reptiles, amphibians, and insects to the Tableau encyclopédique et méthodique...
, in his 1788
Tableau encyclopédique et méthodique des trois regnes de la nature; the type specimen from "Le cap Breton" has since been lost. This species was later placed in its own genus,
Dalatias, which came from the
synonymyIn scientific nomenclature, synonyms are different scientific names used for a single taxon. Usage and terminology are different for zoology and botany.- Zoology :...
of
Constantine RafinesqueConstantine Samuel Rafinesque-Schmaltz, as he is known in Europe, was a nineteenth-century polymath who made notable contributions to the study of prehistoric earthworks in North America, Mesoamerican ancient linguistics, and botany and zoology. His personal life was erratic.Many have called him...
's 1810
Dalatias sparophagus with
S. licha. However, some authorities dispute this on the grounds that
D. sparophagus is a
nomen dubiumIn zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application. Note that in the ICBN and ICNB the phrase "nomen dubium" has no status In zoological nomenclature, a nomen dubium (Latin for "doubtful name", plural nomina dubia) is a scientific name that...
, and prefer to use the next available genus name
Scymnorhinus. The genus name
Dalatias is derived from the Greek
dalos or
dalou, meaning "torch". The specific epithet
licha comes from
la liche, an old French name for this shark. Additional
common nameA common name is a name in general use within a community; it is often contrasted with a scientific name...
s used for the kitefin shark include black shark and darkie Charlie.
Phylogeny and evolution
Cladistic studies have consistently found that the closest relatives of the kitefin shark are the cookiecutter sharks (
IsistiusIsistius is a genus of dogfish sharks in the family Dalatiidae.-Species:* Cigar shark or cookiecutter shark, Isistius brasiliensis
...
), with which they share several
dentitionDentition is the development of teeth and their arrangement in the mouth.All mammals except the monotremes, the xenarthrans, the pangolins, and the cetaceans have up to four distinct types of teeth, with a maximum number for each. These are the incisor , the canine, the premolar, and the molar ...
al,
skeletalIn biology, a skeleton is a rigid framework that provides protection and structure in many types of animal, particularly those of the phylum Chordata and of the superphylum Ecdysozoa. Exoskeletons are external, as is typical of many invertebrates; they enclose the soft tissues and organs of the...
, and
muscularMuscle is the contractile tissue of the body and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
similarities.
Dalatias and
Isistius are believed to have
evolutionarily divergedSpeciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages...
shortly after the
transition between the Cretaceous and TertiaryThe K–T boundary is a geological signature, usually a thin band, dated to Ma . K is the traditional abbreviation for the Cretaceous period, and T is the abbreviation for the Tertiary period...
periods (65.5
MaIn astronomy, geology, and paleontology, mya or "m.y.a." is an abbreviation for "million years ago". Like the related unit bya, mya is traditionally written in lower case...
), as part of a larger
adaptive radiationAn adaptive radiation is a rapid evolutionary radiation characterized by an increase in the morphological and ecological diversity of a single, rapidly diversifying lineage. Phenotypes adapt in response to the environment, with new and useful traits arising...
of dogfish sharks from the deep sea into relatively shallower habitats.
The oldest
fossilFossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous rock formations and sedimentary layers is known as the fossil record...
teeth that definitively belong to the kitefin shark date to the Middle Eocene epoch, such as those recovered from Bortonian-stage deposits (43.0–37.0 Ma) in
New ZealandNew Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses , and numerous smaller islands, most notably Stewart Island/Rakiura and the Chatham Islands. The indigenous Māori named New Zealand Aotearoa, commonly translated as The Land of the Long White Cloud...
.
Dalatias fossil teeth dating to various ages have also been discovered in
EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus Mountains , and the Black Sea to the southeast...
, the former
USSRThe Union of Soviet Socialist Republics was a constitutionally socialist state that existed in Eurasia from 1922 to 1991. The name is a translation of the , tr. Soyuz Sovetskikh Sotsialisticheskikh Respublik, abbreviated СССР, SSSR. The common short name is Soviet Union, from , Sovetskiy Soyuz...
, Japan, and western
IndiaIndia, officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the south, the Arabian Sea on the west, and the Bay of Bengal...
. The fossil material now recognized as belonging to this species were historically described under a multitude of different names.
Distribution and habitat
The kitefin shark has an almost circumglobal range in tropical and warm-temperature waters, consisting of a number of widely separated populations with likely little interchange between them. This shark has not been reported from the eastern Pacific and northern Indian Oceans. In the northern Atlantic, it occurs in the
Georges BankGeorges Bank is a large elevated area of the sea floor which separates the Gulf of Maine from the Atlantic Ocean and is situated between Cape Cod, Massachusetts and Cape Sable Island, Nova Scotia ....
and the northern
Gulf of MexicoThe Gulf of Mexico is the ninth largest body of water in the world. Considered a smaller part of the Atlantic Ocean, it is an ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United...
, and from the
North SeaThe North Sea is a marginal, epeiric sea on the European continental shelf. The Dover Strait and the English Channel in the south and the Norwegian Sea in the north connect it to the Atlantic Ocean. It is more than long and wide, with an area of around...
to
CameroonThe Republic of Cameroon is a unitary republic of central and western Africa. It is bordered by Nigeria to the west; Chad to the northeast; the Central African Republic to the east; and Equatorial Guinea, Gabon, and the Republic of the Congo to the south. Cameroon's coastline lies on the Bight of...
, including around the
British IslesThe British Isles are a group of islands off the northwest coast of continental Europe that include Great Britain, Ireland and numerous smaller islands. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland, and Ireland...
, the
Mediterranean SeaThe Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by Africa, and on the east by the Levant. The sea is technically a part of the Atlantic Ocean, although it...
,
MadeiraMadeira is a Portuguese archipelago in the mid Atlantic Ocean that lies between and . It is one of the Autonomous regions of Portugal, with Madeira Island and Porto Santo Island being the only inhabited islands...
, and the
AzoresThe Azores is a Portuguese archipelago in the Atlantic Ocean, about from Lisbon and about from the east coast of North America. The two westernmost Azorean islands actually lie on the North American plate...
. In the Indian Ocean, it is found off
South AfricaThe Republic of South Africa is a country located at the southern tip of Africa, with a coastline on the Atlantic and Indian Oceans. To the north lie Namibia, Botswana and Zimbabwe, to the east are Mozambique and Swaziland, while Lesotho is an independent country surrounded by South Africa.Modern...
and
MozambiqueMozambique, officially the Republic of Mozambique , is a country in southeastern Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west and Swaziland and South Africa to the southwest. It was explored by Vasco da Gama in 1498...
. In the Pacific, it occurs off Japan,
JavaJava is an island of Indonesia and the site of its capital city, Jakarta. Once the centre of powerful Hindu-Buddhist kingdoms, Islamic sultanates, and the core of the colonial Dutch East Indies, Java now plays a dominant role in the economic and political life of Indonesia...
,
AustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the continental mainland , the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans...
and
New ZealandNew Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses , and numerous smaller islands, most notably Stewart Island/Rakiura and the Chatham Islands. The indigenous Māori named New Zealand Aotearoa, commonly translated as The Land of the Long White Cloud...
, and the
Hawaiian IslandsThe Hawaiian Islands are an archipelago of 19 islands and atolls, numerous smaller islets, and undersea seamounts in the North Pacific Ocean, extending some 1,500 miles from the island of Hawaii in the south to northernmost Kure Atoll. Excluding Midway, which is an unincorporated territory of the...
. There is a single record of this species in the southern Atlantic, from off southern
BrazilBrazil , officially the Federative Republic of Brazil , is a country in South America. It is the fifth largest country by geographical area, occupying nearly half of South America, the fifth most populous country, and the fourth most populous democracy in the world. Bounded by the Atlantic Ocean...
.
An offshore, deepwater species, the kitefin shark is most common at a depth of 200–600 m (660–2,000 ft), but has been captured from the surface to as deep as 1,800 m (5,900 ft). Off the
AzoresThe Azores is a Portuguese archipelago in the Atlantic Ocean, about from Lisbon and about from the east coast of North America. The two westernmost Azorean islands actually lie on the North American plate...
this shark segregates by sex, with females most common around a depth of and males most common around . The kitefin shark inhabits the outer continental shelves and upper continental slopes, and is also found around oceanic islands and
seamountA seamount is a mountain rising from the ocean seafloor that does not reach to the water's surface , and thus is not an island. These are typically formed from extinct volcanoes, that rise abruptly and are usually found rising from a seafloor of 1,000–4,000 meters depth...
s. It is the only member of its family that tends to be found close to the sea floor as opposed to in the middle of the water column, though on occasion it has been captured well above the bottom.
Description
The kitefin shark has a moderately elongated body with a very short, rounded snout. The eyes and
spiracleSpiracles are small openings on the surface of some animals that usually lead to respiratory systems.In elasmobranchs , a spiracle is found behind each eye, and is often used to pump water through the gills while the animal is at rest .-Spiracles in insects:Insects and some more advanced spiders...
s are large. The lips are thick with pleats or fringes, though are not modified to be
suctorialSuctorial pertains to the adaptation for sucking or suction, as possessed by marine parasites such as the Cookiecutter shark, specifically in a specialised lip organ enabling attachment to the host....
. There are 16–21 tooth rows in the upper jaw and 17–20 tooth rows in the lower jaw. The upper teeth are small and spike-shaped, curving slightly towards the corners of the mouth. The lower teeth are very large, knife-shaped, and serrated, with their bases interlocking to form a continuous cutting surface.
The first
dorsal finA dorsal fin is a fin located on the backs of some fish, whales, dolphins, and porpoises, as well as the ichthyosaurs. Depending on the species, an animal can have up to three of them. Its main purpose is to stabilize the animal against rolling and assist in sudden turns...
is slightly smaller and shorter-based than the second, and neither has spines. The first dorsal fin originates behind the free rear tip of the pectoral fins, while the second originates above the middle of the pelvic fin bases. The pectoral fins are short and rounded. The caudal fin has a prominent upper lobe with a well-developed notch near the tip, and a barely present lower lobe. The form and arrangement of the fins is similar to the
Portuguese dogfishThe Portuguese dogfish, Centroscymnus coelolepis, is a sleeper shark of the family Dalatiidae, found around the world on continental slopes and abyssal plains between latitudes 64°N and 48°S, at depths of between 150 and 3,700 m. It reaches a length of 1.2 m....
(
Centroscymnus coelolepis), from which this species can be distinguished by the lack of fin spines. The
dermal denticleDenticles are body surface structures found on some fish and insects. Literally, the term means "small tooth" and refer to the structures' shape....
s are small and flat, with a single horizontal ridge ending in a point.
The coloration is a uniform dark brown or gray, sometimes with faint black spots on the back. The fins have white or translucent margins, and the tip of the caudal fin is black. An 90 cm (3.0 ft) long kitefin shark with partial
albinismAlbinism is a form of hypopigmentary congenital disorder, characterized by a partial or total lack of melanin pigment in the eyes, skin and hair, or more rarely...
, lacking
pigmentA pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
on 59% of its body, was caught in the
Gulf of GenoaThe Gulf of Genoa is the northernmost part of the Ligurian Sea. The width of the gulf is about 125 km, from the city of Imperia in the west to La Spezia in the east. The largest city on the its coast is Genoa, which has an important port....
in 2003. Unlike in a previous case of an albino Portuguese dogfish, the abnormal coloration of this individual had not diminished its ability to capture prey. Most kitefin sharks are 1.0–1.4 m (2.5–4.0 ft) long and weigh ; the maximum reported length is 1.6 m (5.2 ft), possibly 1.8 m (6.0 ft).
Biology and ecology
Relatively common where it occurs, kitefin sharks are usually solitary in nature but may form small groups. It is a slow swimmer with a large
liverThe liver is a vital organ present in vertebrates and some other animals; it has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
filled with
squaleneSqualene is a natural organic compound originally obtained for commercial purposes primarily from shark liver oil, though botanic sources are used as well, including amaranth seed, rice bran, wheat germ, and olives. All higher organisms produce squalene, including humans. It is a hydrocarbon and a...
, a
lipidLipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, phospholipids, and others...
less dense than water, allowing it to maintain neutral buoyancy and hover above the bottom with little effort. Studies off the coast of
North AfricaNorth Africa or Northern Africa is the northernmost region of the African continent, linked by the Sahara to Sub-Saharan Africa.Geopolitically, the UN definition of Northern Africa includes the following seven countries or territories; Algeria, Egypt, Libya, Morocco, Sudan, Tunisia,Mauritania, and...
and in the Gulf of Genoa have found males outnumbering females by 2:1 and 5:1 respectively; this imbalanced
sex ratioSex ratio is the ratio of males to females in a population. The primary sex ratio is the ratio at the time of conception, secondary sex ratio is the ratio at time of birth, and tertiary sex ratio is the ratio of mature organisms....
has not been observed off South Africa and may reflect sampling bias. The kitefin shark is preyed upon by larger fishes and sharks, as well as by
sperm whaleThe sperm whale, , is a species of marine mammal in the order cetacea, a toothed whale with the largest brain of any animal. The whale was named after the milky-white waxy substance, spermaceti, found in its head and originally mistaken for sperm...
s (
Physeter macrocephalus). Parasite data on this species is limited; an examination of two sharks caught off
IrelandIreland is the third-largest island in Europe and the twentieth-largest island in the world. It lies to the north-west of continental Europe and is surrounded by hundreds of islands and islets. To the east of Ireland, separated by the Irish Sea, is the island of Great Britain...
found three
nematodeThe "roundworms" or "nematodes" are the most diverse phylum of pseudocoelomates, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 80,000 have been described, of which over 15,000 are parasitic. It has been estimated that the total number of...
s in the
stomachIn most mammals, the stomach is a hollow, muscular organ of the gastrointestinal tract , between the esophagus and the small intestine. It is involved in the second phase of digestion, following mastication . The word stomach is derived from the Latin stomachus, which derives from the Greek word...
lumenLumen can mean:* Lumen , the SI unit of luminous flux* Lumen , the cavity or channel within a tubular structure* Thylakoid lumen, the inner membrane space of the chloroplast...
. One could be identified as
Anisakis simplex L
3, while another may have been a
larvaA larva is a young form of animal with indirect development, going through or undergoing metamorphosis ....
l
Raphidascaris.
A powerful and versatile deepwater predator, the short, robust jaws of the kitefin shark give it an enormously strong bite. It feeds mainly on bony fishes (including deepwater smelts,
viperfishA viperfish is a deepwater fish in the genus Chauliodus, with long, needle-like teeth and hinged lower jaws. They grow to lengths of 30 to 60 cm . Viperfish stay near lower depths in the daytime and shallow at night. Viperfish mainly stay in tropical and temperate waters...
es,
scaly dragonfishStomiidae is a family of deep-sea ray-finned fish, including the barbeled dragonfishes, stareaters and loosejaws.Stomiids are generally elongated fish with black or near-black bodies, but they are highly variable in form, and are sometimes grouped into multiple different families as a result. The...
es,
barracudinaBarracudinas are about 50 species of marine fishes of the family Paralepididae, found almost worldwide in deep waters.They are elongated, slender fish with large eyes, and a pointed snout containing fang-like teeth...
s,
greeneyeGreeneyes are deep-sea aulopiform marine fishes in the small family Chlorophthalmidae. Thought to have a circumglobal distribution in tropical and temperate waters, the family contains just 18 species in two genera...
s,
lanternfishLanternfishes are small, deep sea fish of the large family Myctophidae. One of two families in the order Myctophiformes, the Myctophidae are represented by 246 species in 33 genera, and are found in oceans worldwide. They are aptly named after their conspicuous use of bioluminescence...
es, bristlemouths,
cod and other gadidsGadidae is a family of marine fish, included in the order Gadiformes. It includes the cod, haddock, whiting, and pollock.Most species of gadid are found in temperate waters of the northern hemisphere, although there are some exceptions. They are generally medium sized fish, and are distinguished...
,
grenadierGrenadiers or rattails are generally large, brown to black gadiform marine fish of the family Macrouridae...
s,
deepwater scorpionfishSetarchidae is a small family of scorpionfishes.Not all classifications recognise this family; Nelson and ITIS include it in the family Scorpaenidae....
es,
bonitoBonito is a name given to various species of medium-sized, predatory fish of the genus Sarda, in the mackerel family, including the common or Atlantic bonito and the Pacific bonito....
, snake mackerels,
deepwater cardinalfishDeepwater cardinalfishes are perciform fishes in the family Epigonidae.They are small fishes: the largest species, Epigonus telescopes, reaches 75 cm in length, and most species grow to no more than 20 cm or so....
es, and
sea toadSea toads are a family, Chaunacidae, of deep-sea anglerfishes.They are bottom-dwelling fishes found on the continental slopes of the Atlantic, Indian and Pacific Oceans, at depths of up to ....
s), but also takes a wide variety of other animals, including skates, smaller sharks (
GaleusGaleus is a genus of catshark in the family Scyliorhinidae.-Species:* Antilles catshark, Galeus antillensis
Springer, 1979 * Roughtail catshark, Galeus arae
...
,
Squalus,
EtmopterusEtmopterus, commonly known as lantern sharks, is a genus of squaliform sharks in the family Etmopteridae.-Species:* New Zealand lanternshark, Etmopterus baxteri
...
and
CentrophorusCentrophorus is a genus of squaliform sharks. They are deep-water sharks found in temperate and tropical oceans throughout the world. They are characterized by grey or brown bodies, large green eyes, and spines on both dorsal fins...
),
squidSquid are marine cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms and two longer tentacles arranged in pairs...
and
octopusThe octopus is a cephalopod of the order Octopoda. The octopus inhabits many diverse regions of the ocean, especially coral reefs. The term may also be used to refer only to those creatures in the genus Octopus...
, crustaceans (amphipods, isopods,
shrimpShrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
and
lobsterClawed lobsters compose a family of large marine crustaceans. Lobsters are economically important as seafood, forming the basis of a global industry that nets US$31.8 billion in trade annually....
s), polychaete worms, and siphonophores. Like the related cookiecutter shark, the kitefin shark is also capable of excising chunks of flesh from animals larger than itself, including other sharks and
whaleWhale is the common name for marine mammals of the order Cetacea. The term whale is sometimes used to refer to all cetaceans, but in more common English usage it generally excludes the members of the Delphinoidea superfamily, such as dolphins and porpoises...
s. The presence of fast-swimming fishes in its diet suggests the kitefin shark may scavenge, or have some other means of capturing faster prey. In the Mediterranean, bony fishes are the most important food year-round, with the second-most important prey being sharks in the winter and spring, crustaceans in the summer, and cephalopods in the fall. Captured males are more likely to have full stomachs than females for unknown reasons.
Reproduction in the kitefin shark is aplacental viviparous, with the
embryoAn embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
s hatching inside the
uterusThe uterus is a major female hormone-responsive reproductive sex organ of most mammals, including humans. It is within the uterus that the fetus develops during gestation. The term uterus is used consistently within the medical and related professions; the Germanic term, womb is more common in...
and being sustained to term by a
yolk sacThe yolk sac is a membranous sac attached to an embryo, providing early nourishment in the form of yolk in bony fishes, sharks, reptiles, birds, and primitive mammals...
. Adult females have two functional
ovariesThe ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in females are homologous to testes in males, in that they are both gonads and endocrine glands.-Human anatomy:...
and two functional uteruses; the uterus is not divided into compartments. In the Mediterranean, breeding occurs in the fall and birthing in summer; females may have a year of rest in between pregnancies. The litter size is 10–16, increasing with female size. The young are born at a length of , varying by geographic location, after a possible
gestation periodFor mammals the gestation period is the time in which a fetus develops, beginning with fertilization and ending at the embryo stage. The duration of this period varies between species.-Duration:...
of two years. The males mature sexually at a length of 77–121 cm (2.5–4.0 ft), and the females at a length of 117–159 cm (3.8–5.2 ft). There is no relationship between an individual's size at birth, size at maturity, and maximum size.
Human interactions
The kitefin shark inhabits depths too great for it to be a danger to humans. Its upper teeth have been found lodged in underwater fiberoptic cables. This species has a long history of human exploitation: the meat is consumed in the eastern Atlantic and Japan, and the
offalOffal is a culinary term used to refer to the entrails and internal organs of a butchered animal. The word does not refer to a particular list of organs, but includes most internal organs other than muscles or bones...
processed into fishmeal. The liver oil is utilized in Portugal, Japan, and South Africa. The skin is made into a type of
shagreenShagreen is a type of leather or rawhide consisting of rough untanned skin, formerly made from a horse's back or that of an onager , and typically dyed green. Shagreen is now commonly made of the skins of sharks and rays. The word derives from the French chagrin which in turn is borrowed from...
useful in the making of furniture and jewelry, and is also favored for the manufacture of "boroso", a Spanish polished
leatherLeather is a material created through the tanning of hides and skins of animals, primarily cattlehide. The tanning process converts the putrescible skin into a durable and versatile material....
. This shark has no commercial value in the western Atlantic.
Fisheries operating off Portugal and Japan are responsible for most commercial landings of the kitefin shark, generally as bycatch in bottom trawls and on hook-and-line. Portugal reported a kitefin shark bycatch of 282 tons in 2000 and 119 tons in 2003; in other areas of the northeastern Atlantic this shark is rare and reported catches are likely to be misidentifications of other species. Catches by the Australian South East Trawl Fishery are increasing following the relaxation of regulations regarding seafood
mercuryMercury , also called quicksilver or hydrargyrum , is a chemical element with the symbol Hg and atomic number 80...
content; this species is not included under Australian fishery
quotaQuota may refer to:A level business* Quota samplingAffirmative action* Racial quota* Reservation in India* Quotas in PakistanComputing* Disk quota* Bandwidth cap, the quota for upload or download of dataElectoral systems...
s. New Zealand kitefin shark catches peaked from 1986 to 1997.
Due to a paucity of specific fisheries data, the kitefin shark is listed as
Data DeficientData Deficient is a category applied by the IUCN to a species when the available information is not sufficient for a proper assessment of conservation status to be made. This does not necessarily indicate that the species has not been extensively studied; but it does indicate that little or no...
on the
IUCN Red ListThe IUCN Red List of Threatened Species , founded in 1948, is the world's most comprehensive inventory of the global conservation status of plant and animal species. The International Union for the Conservation of Nature and Natural Resources is the world's main authority on the conservation...
. However, the continuing expansion of commercial fisheries into the deep sea has raised concerns about the vulnerability of this and other deepwater shark species to
overfishingOverfishing occurs when fishing activities reduce fish stocks below an acceptable level. This can occur in any body of water from a pond to the oceans....
, as these sharks have slow growth and reproductive rates. This is exemplified by the rapid stock depletion and collapse of the Azores kitefin shark fishery. This targeted fishery began in the early 1970s for the production of liver oil. In the early 1980s, the fishing fleet was enlarged with the addition of industrial vessels equipped with demersal gillnets, resulting in a fishery peak in 1984 of 937 tons landed. After 1991, kitefin shark catches declined precipitously to under 15 tons annually which, along with a drop in the global price of liver oil, led to the fishery becoming unprofitable by the end of the decade. Population assessments suggested the northwestern Atlantic stock had fallen to 50% of the pre-exploitation biomass.