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

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

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 tiger shark, bull shark, le ...

, in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

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 located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...

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

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

s, second dorsal fin, and

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

lower lobe. The Pondicherry shark is critically endangered. It was once found throughout Indo-Pacific coastal waters from the Gulf of Oman to

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torr ...

, and is known to enter fresh water. Fewer than 20 specimens are available for study, and most aspects of its natural history are unknown. It probably feeds on bony fishes, cephalopods, and

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...

s, and gives birth to live young with the embryos forming a

placenta The placenta 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 the physically separate mate ...

l connection to their mother. While the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of nat ...

(IUCN) has listed the Pondicherry shark as Critically endangered, it had been thought to be extinct since the 1970s. It continues to be found in markets, most recently in 2019 at a local fishing village in southern Sri Lanka after the continuous efforts made by the famous biologist and conservationist

Forrest Galante Forrest Galante (born March 31, 1988) is an American outdoor adventurer, television personality, and conservationist. He works in the field of wildlife biology, specializing in the exploration of animals on the brink of extinction. He is the hos ...

, and his wife, zoologist Jessica Summerfield, in a special episode 'The Lost Shark' of the Discovery channel program 'Extinct or Alive
Newsweek
The specimen found will be displayed in the museum of Sri Lanka to raise awareness of the critically endangered species. 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 Pondicherry has been spotted in rivers in India in the late 2010s. A Pondicherry shark was caught in the Menik Ganga (river) in SE Sri Lanka in 2011. It was photographed and released alive. An illustration of the shark appears on page 298 of 'Sri Lankan Freshwater Fishes'.

Taxonomy

The first scientific description 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: * Puducherry (union territory), a union territory of India ** Pondicherry, capital of the union territory of Puducherry ** Puducherry district, a district of the union territory of Puducherry ** Puducherry t ...

(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 nor a syntype). O ...

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

zoologist Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the animal kingdom, including the structure, embryology, evolution, classification, habits, and d ...

Achille Valenciennes. The specific epithet ''hemiodon'' is derived from the

Greek Greek may refer to: Greece 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 ...

''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 histo ...

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 * Dorsal c ...

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 "Jack" Garrick (1928 – August 30, 2018) was a New Zealand ichthyologist. He specialized in elasmobranchs and published many books and articles about shark and ray biology. In 1982, he published a thorough taxonomy on sharks of ...

followed up on earlier taxonomic work by

Leonard Compagno Leonard Joseph Victor Compagno is 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 Agriculture Organ ...

and synonymized ''Hypoprion'' with '' Carcharhinus''. Another common name for the Pondicherry shark is long nosed shark.

Phylogeny

The evolutionary relationships 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 feed ...

(''C. dussumieri''),

Borneo shark The Borneo shark (''Carcharhinus borneensis'') is a species of requiem shark, and part of the family Carcharhinidae. Extremely rare, it is known only from inshore waters around Mukah in northwestern Borneo, though it may once have been more wi ...

(''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 membranes. 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 up ...

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 bifurc ...

, 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 con ...

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

caudal peduncle Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as see ...

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 denticles; 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 Indo-Pacific. 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 Gulf of Oman,

Borneo Borneo (; id, Kalimantan) is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, and ea ...

, and

Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's mos ...

. 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 the shores of South China (hence the name), in the west by the Indochinese Peninsula, in the east by the islands of Taiwan and northwestern Phi ...

, other parts of

Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical south-eastern region of Asia, consisting of the regions that are situated south of mainlan ...

such as Vietnam and the Philippines,

, and northern Australia. This species inhabits inshore waters. Several older sources reported that it could be found in rivers such as the

Hooghli River The Bhagirathi Hooghly River (Anglicized alternatively spelled ''Hoogli'' or ''Hugli'') or the 'Bhāgirathi-Hooghly', called the Ganga or the Kati-Ganga in mythological texts, is the eastern distributary of the Ganges River in West Bengal, In ...

and the

Saigon River The Saigon River ( vi, Sông Sài Gòn) is a river located in southern Vietnam that rises near Phum Daung in southeastern Cambodia, flows south and south-southeast for about and empties into the Soài Rạp, which in its turn empties into the ...

. 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 and parts of Australia. Taxonomy This genus contains only three extant species. Furth ...

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

Biology and ecology

The diet of the Pondicherry shark is thought to consist of small bony fishes, cephalopods, and

s. A

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

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 is Cestodaria). Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Cesto ...

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

viviparous Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the ...

with the developing embryos 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 might be considered synonymous with adulthood, but here puberty is the name for the process of biological sexual maturation, while adulthood is based on cultural definit ...

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. However, in 2016, the Pondicherry shark was rediscovered in the Sri Lankan Menik and Kumbukkam rivers. Two photographs of this species exist; one taken from above by a group of nature enthusiasts, as well as one taken from the side by a freshwater fish survey. Given that

artisan An artisan (from french: artisan, it, artigiano) 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 ...

and

commercial fishing Commercial fishing is the activity of catching 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 ...

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

(IUCN) has listed the Pondicherry shark as Critically endangered 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