The Pondicherry shark (''Carcharhinus hemiodon'') is an extremely rare

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

requiem shark Requiem sharks are sharks of the family Carcharhinidae in the order Carcharhiniformes. They are migratory, live-bearing sharks of warm seas (sometimes of brackish or fresh water) and include such species as the bull shark, lemon shark, blac ...

, in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Carcharhinidae. A small and stocky gray shark, it grows not much longer than and has a fairly long, pointed snout. This species can be identified by the shape of its upper teeth, which are strongly serrated near the base and smooth-edged near the tip, and by its first

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

, which is large with a long free rear tip. Furthermore, this shark has prominent black tips on its

pectoral fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...

s, second dorsal fin, and

caudal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...

lower lobe. The Pondicherry shark is critically endangered. It was once found throughout

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

coastal waters from the

Gulf of Oman The Gulf of Oman or Sea of Oman ( ''khalīj ʿumān''; ''daryâ-ye omân''), also known as Gulf of Makran or Sea of Makran ( ''khalīj makrān''; ''daryâ-ye makrān''), is a gulf in the Indian Ocean that connects the Arabian Sea with th ...

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; , fossilized , also known as Papua or historically ) is the List of islands by area, world's second-largest island, with an area of . Located in Melanesia in the southwestern Pacific Ocean, the island is ...

, and is known to enter

fresh water Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salt (chemistry), salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include ...

. Fewer than 20 specimens are available for study, and most aspects of its natural history are unknown. It probably feeds on

bony fish Osteichthyes ( ; ), also known as osteichthyans or commonly referred to as the bony fish, is a Biodiversity, diverse clade of vertebrate animals that have endoskeletons primarily composed of bone tissue. They can be contrasted with the Chondricht ...

es,

cephalopod A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...

s, and

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s, and gives birth to live young with the

embryo An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...

s forming a

placenta The placenta (: placentas or placentae) is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas, and waste exchange between ...

l connection to their mother. While the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...

(IUCN) has listed the Pondicherry shark as

Critically endangered An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...

, it had been thought to be extinct since the 1970s. It is probably threatened by intense and escalating fishing pressure throughout its range. The shark is among the 25 "most wanted lost" species that are the focus of Global Wildlife Conservation's "Search for Lost Species" initiative. The last definitive sighting was from 1979 in India, though putative sightings have been recently reported, some of which were considered to be erroneous.

Taxonomy

The first

scientific description A species description is a formal scientific description of a newly encountered species, typically articulated through a scientific publication. Its purpose is to provide a clear description of a new species of organism and explain how it diffe ...

of the Pondicherry shark was authored by German

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 (biology), cell, a multicellular organism, or a Community (ecology), community of Biological inter ...

s Johannes Müller and

Jakob Henle Friedrich Gustav Jakob Henle (; 9 July 1809 – 13 May 1885) was a German physician, pathologist, and anatomist. He is credited with the discovery of the loop of Henle in the kidney. His essay, "On Miasma and Contagia," was an early argument for ...

in their 1839 ''Systematische Beschreibung der Plagiostomen''. Their account was based on a long immature male from

Puducherry Puducherry or Pondicherry may refer to: Places in India * Puducherry (union territory), formerly known as Pondicherry ** Puducherry (city), capital of the union territory of Puducherry ** Puducherry district The Puducherry District, also know ...

(formerly Pondicherry), India and three more

paratype In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype (biology), isotype ...

s from the same region. Müller and Henle attributed the name for the new species, ''Carcharias (Hypoprion) hemiodon'', to French

zoologist Zoology ( , ) is the scientific study of animals. Its studies include the structure, embryology, classification, habits, and distribution of all animals, both living and extinct, and how they interact with their ecosystems. Zoology is one ...

Achille Valenciennes Achille Valenciennes (9 August 1794 – 13 April 1865) was a French zoology, zoologist. Valenciennes was born in Paris, and studied under Georges Cuvier. His study of parasitic worms in humans made an important contribution to the study of parasi ...

. The

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

''hemiodon'' is derived from the

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

''hemi'' ("half") and ''odon'' ("tooth"). In 1862,

Theodore Gill Theodore Nicholas Gill (March 21, 1837 – September 25, 1914) was an American ichthyologist, mammalogist, malacologist, and librarian. Career Born and educated in New York City under private tutors, Gill early showed interest in natural hist ...

elevated ''Hypoprion'' to the rank of full genus and also placed the Pondicherry shark in its own genus, ''Hypoprionodon'', based on the relative positions of the

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage The fus ...

and

s. Subsequent authors generally accepted Gill's first revision but not his second, and thus this species became known as ''Hypoprion hemiodon''. In 1985,

Jack Garrick John Andrew Frank Garrick (24 March 1928 – 30 August 2018) was a New Zealand ichthyologist. Career Garrick specialised in elasmobranchs and published many books and articles about shark and ray biology. In 1982, he published a thorough taxonom ...

followed up on earlier

taxonomic 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme of classes (a taxonomy) and the allocation ...

work by

Leonard Compagno Leonard Joseph Victor Compagno (1943-2024) was an international authority on shark taxonomy and the author of many scientific papers and books on the subject, best known of which is his 1984 catalogue of shark species produced for the Food and Agri ...

and synonymized ''Hypoprion'' with ''

Carcharhinus ''Carcharhinus'' is the type genus of the family (biology), family Carcharhinidae, the requiem sharks. One of 12 genera in its family, it contains over half of the species therein. It contains 35 extant and eight extinct species to date, with lik ...

''. Another

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often con ...

for the Pondicherry shark is long nosed shark.

Phylogeny

The

evolutionary relationships Evolution is the change in the heritable characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, resulting in certai ...

of the Pondicherry shark are uncertain. In a 1988 study based on morphological data, Compagno tentatively grouped it with the

smalltail shark The smalltail shark (''Carcharhinus porosus'') is a species of requiem shark, and part of the family Carcharhinidae. It is found in the western Atlantic Ocean, from the northern Gulf of Mexico to southern Brazil. It inhabits shallow waters close ...

(''C. porosus''),

blackspot shark The blackspot shark (''Carcharhinus sealei'') is a small species of requiem shark in the family Carcharhinidae found in the tropical Indo-West Pacific Ocean between latitudes 24°N and 30°S, from the surface to a depth around . Its length is ...

(''C. sealei''), spottail shark (''C. sorrah''), creek whaler (''C. fitzroyensis''),

whitecheek shark The whitecheek shark or widemouth blackspot shark (''Carcharhinus dussumieri'') is a requiem shark of the family Carcharhinidae, found in the Indo-West Pacific Ocean between latitudes 34°N and 25°S. It can reach a length of 1 m. It fee ...

(''C. dussumieri''), Borneo shark (''C. borneensis''), and hardnose shark (''C. macloti'').

Description

The Pondicherry shark has a robust build and a moderately long, pointed snout. The large and circular eyes are equipped with

nictitating membrane The nictitating membrane (from Latin '' nictare'', to blink) is a transparent or translucent third eyelid present in some animals that can be drawn across the eye from the medial canthus to protect and moisten it while maintaining vision. Most ...

s. Each nostril is broad with a small, narrow nipple-shaped lobe on the anterior rim. The arched mouth lacks conspicuous furrows or enlarged pores at the corners. The upper and lower jaws contain 14–15 and 12–14

tooth row Sharks continually shed their teeth; some Carcharhiniformes shed approximately 35,000 teeth in a lifetime, replacing those that fall out. There are four basic types of shark teeth: dense flattened, needle-like, pointed lower with triangular upp ...

s on either side respectively; in addition, there are one or two rows of small teeth at the upper and lower symphyses (jaw midpoints). The upper teeth have a single narrow, smooth-edged central

cusp A cusp is the most pointed end of a curve. It often refers to cusp (anatomy), a pointed structure on a tooth. Cusp or CUSP may also refer to: Mathematics * Cusp (singularity), a singular point of a curve * Cusp catastrophe, a branch of bifu ...

, flanked on both sides by very large serrations. The lower teeth are narrower and more upright than the uppers, and may be smooth to finely serrated. The five pairs of

gill slit Gill slits are individual openings to gills, i.e., multiple gill arches, which lack a single outer cover. Such gills are characteristic of cartilaginous fish such as sharks and rays, as well as deep-branching vertebrates such as lampreys. In c ...

s are fairly long. Originating below the fourth pair of gill slits, the pectoral fins are short, broad, and falcate (sickle-shaped) with pointed tips. The first dorsal fin is tall and falcate with a distinctively long free rear tip, and is positioned just behind the pectoral fin bases. The second dorsal fin is large and tall without a notably elongated free rear tip, and is positioned over or slightly behind the

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

. Usually there is no midline ridge between the dorsal fins, and when present the ridge is slight. The

caudal peduncle Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...

has a deep crescent-shaped notch at the upper

origin. The asymmetrical caudal fin has a well-developed lower lobe and a longer upper lobe with a notch in the trailing margin near the tip. The skin is covered by overlapping

dermal denticle A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scale (zoology), scales, which can also provide effective Underwater camouflage, camouflage through the us ...

s; each denticle has three horizontal ridges leading to three (rarely five) marginal teeth. This species is gray above and white below, with an obvious pale stripe on the flanks. The pectoral fins, second dorsal fin, and lower caudal fin lobe are prominently tipped in black, while the first dorsal fin and dorsal caudal fin lobe are narrowly edged in black. The maximum size reached by the Pondicherry shark is uncertain due to a lack of large specimens, but is probably not much greater than .

Distribution and habitat

The Pondicherry shark appears to have been broadly distributed in the

. It may have once been common, as it was reportedly a regular catch off India and Pakistan, but is now extremely rare. Most of the known specimens were collected from India, with more specimens from the

Borneo Borneo () is the List of islands by area, third-largest island in the world, with an area of , and population of 23,053,723 (2020 national censuses). Situated at the geographic centre of Maritime Southeast Asia, it is one of the Greater Sunda ...

, and

Java Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...

. There are also less reliable records from the

South China Sea The South China Sea is a marginal sea of the Western Pacific Ocean. It is bounded in the north by South China, in the west by the Indochinese Peninsula, in the east by the islands of Taiwan island, Taiwan and northwestern Philippines (mainly Luz ...

, other parts of

Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...

such as Vietnam and the Philippines,

, and northern Australia. This species inhabits

inshore A coast (coastline, shoreline, seashore) is the land next to the sea or the line that forms the boundary between the land and the ocean or a lake. Coasts are influenced by the topography of the surrounding landscape and by aquatic erosion, su ...

waters. Several older sources reported that it could be found in rivers such as the

Hooghli River The Hooghly River (, also spelled ''Hoogli'' or ''Hugli'') is the westernmost distributary of the Ganges, situated in West Bengal, India. It is known in its upper reaches as the Bhagirathi. The Bhagirathi splits off from the main branch of the G ...

and the

Saigon River The Saigon River () is a river located in southern Vietnam that rises near Phum Daung in southeastern Cambodia, flows south and southeast for about and empties into the Nhà Bè River, which in its turn empties into the South China Sea some no ...

. These reports may have confused a

river shark ''Glyphis'' is a genus in the family Carcharhinidae, commonly known as the river sharks. They live in rivers or coastal regions in and around south-east Asia, Africa and parts of Australia. Taxonomy This genus contains only three extant specie ...

(''Glyphis'' sp.) for the Pondicherry shark; if accurate, they would suggest this species to be tolerant of low

salinity Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...

Biology and ecology

The diet of the Pondicherry shark is thought to consist of small

es,

s, and

s. A

parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

documented from this species is the

tapeworm Eucestoda, commonly referred to as tapeworms, is the larger of the two subclasses of flatworms in the class Cestoda (the other subclass being Cestodaria). Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Ce ...

'' Acanthobothrium paramanandai''. Like other requiem sharks, it is

viviparous In animals, viviparity is development of the embryo inside the body of the mother, with the maternal circulation providing for the metabolic needs of the embryo's development, until the mother gives birth to a fully or partially developed juve ...

with the developing

s sustained to term via a

l connection to the mother, though specific details are unknown. The smallest known specimen is a female long, which may be close to the birth size.

Sexual maturity Sexual maturity is the capability of an organism to reproduce. In humans, it is related to both puberty and adulthood. ''Puberty'' is the biological process of sexual maturation, while ''adulthood'', the condition of being socially recognized ...

is attained at a length of over .

Human interactions

Harmless to humans, the Pondicherry shark was caught and used for meat. Fewer than 20 specimens have been deposited in museum collections, most of which were collected prior to 1900. This shark's rarity originally led to fears that it may be possibly extinct, with the last verifiable record from 1979 in India. In 2014, the Pondicherry shark was claimed to have been discovered in the Sri Lankan Menik rivers with two photographs as evidence, but the IUCN rejected this sighting as a misidentified juvenile bull shark. Putative sightings from the rivers of India in the late 2010s have also recently been reported. Given that

artisan An artisan (from , ) is a skilled craft worker who makes or creates material objects partly or entirely by hand. These objects may be functional or strictly decorative, for example furniture, decorative art, sculpture, clothing, food ite ...

and

commercial fishing Commercial fishing is the activity of catching fish and other seafood for Commerce, commercial Profit (economics), profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice ...

activity across its range is heavy, unregulated, and intensifying, the

(IUCN) has listed the Pondicherry shark as

critically endangered An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...

and placed a high priority on locating any surviving populations.

References

External links

"''Carcharhinus hemiodon'', Pondicherry shark" at FishBase

"Species description of ''Carcharhinus hemiodon''" at Shark-References.com
{{Taxonbar, from=Q1516764 Carcharhinus Fish of the Indian Ocean Fish of the Pacific Ocean Fish of Oceania Marine fish of Asia Fish of Southeast Asia Fish of New Guinea Critically endangered fish Critically endangered fauna of Asia Critically endangered fauna of Oceania Fish described in 1839 Taxa named by Friedrich Gustav Jakob Henle Taxa named by Johannes Peter Müller