Sharks Codexery

Borneo shark

Rare requiem shark with unique mouth pores, found only off northwestern Borneo.

Last updated

Borneo shark

Naturalis Biodiversity Center · via Wikipedia: Borneo shark · CC0

This shark is one of the rarest in the world—every recent specimen came from just one fishing port in Sarawak.[1] Conservation groups list the Borneo shark as Critically Endangered, which means it faces an extremely high risk of extinction in the wild.[2][3] The Borneo shark is small and slim-bodied, a type of requiem shark that may now live only in shallow coastal waters off northwestern Borneo, though it used to be found in more places.[1]

Scientific classification

  1. KingdomAnimalia
  2. PhylumChordata
  3. ClassChondrichthyes
  4. SubclassElasmobranchii
  5. DivisionSelachii
  6. OrderCarcharhiniformes
  7. FamilyCarcharhinidae
  8. GenusCarcharhinus
  9. SpeciesCarcharhinus borneensis

Named by (Bleeker, 1858)

Close relatives

Other species of Carcharhinus with a Codexery entry.

Sources: Wikipedia taxobox: Borneo shark (CC BY-SA 4.0) · order, family and genus agree with WoRMS AphiaID 271319 (CC BY 4.0)

Conservation status

Critically Endangered (CR)

  1. LC
  2. NT
  3. VU
  4. EN
  5. CR▲ this species
  6. EW
  7. EX
Population trend
Not held in our sources — see the assessment
Assessment published
2021

Source: IUCN Red List assessment · GBIF copy of the Red List category

How big is it?

Size comparison: Borneo shark and a personA 0.65 m long borneo shark drawn to scale next to a 1.8 m tall person. Schematic shapes, not a likeness.0.65 m1.8 m

Largest length in the source, 0.65 m, next to a 1.8 m person.

Diagram: drawn by Codexery, schematic shapes to scale (not a likeness). Length: Wikipedia: Borneo shark

Where the borneo shark has been recorded

Where the borneo shark has been recordedPlaces named in the text; marked places: Mukah, BorneoMukahBorneo

Map: drawn by Codexery. Data: Natural Earth basemap (public domain) · place coordinates: Wikipedia (CC BY-SA 4.0)

Description

The skin is covered with small, overlapping dermal denticles—tiny tooth-like scales—each with three horizontal ridges.[4] The body is slate-gray above, darkening toward the tips of the dorsal fins and upper tail fin lobe.[4] This shark has a long, pointed snout. Its nostrils are slanted and slit-like, with narrow, nipple-shaped flaps of skin right in front of them.[4] Its eyes are pretty big and round, and each one comes with a nictitating membrane – that's a protective third eyelid.[4]

The upper jaw holds 25 to 26 rows of teeth, and the lower jaw holds 23 to 25 rows.[4] The first dorsal fin is large and triangular, with a blunt tip and a trailing edge that curves in a wavy line.[4]

Distribution and habitat

Every recent Borneo shark specimen came only from fishery landing sites at Mukah in Sarawak, even though people have surveyed the rest of Borneo thoroughly.[1] Several fishery surveys in areas where the shark used to live couldn't find any.[2]

Human interactions

The shark's conservation status remains risky because it lives in such a tiny area, and those waters are heavily fished by both small-scale and commercial operations.[2]

Taxonomy and phylogeny

In 1988, Leonard Compagno tentatively grouped the Borneo shark with several other small requiem sharks, though it resembles sharpnose sharks in traits like enlarged pores near the mouth.[5] Nobody is really sure how the Borneo shark is related to other sharks.[5] Still, other body features clearly place it in the genus Carcharhinus.[6]

References

  1. Wikipedia, "Borneo shark" (CC BY-SA 4.0), which cites: "Descriptions of New Sharks and Rays from Borneo", CSIRO Marine and Atmospheric Research, 2010, p. 17–28; Last, P.R., "Sharks and Rays of Borneo", CSIRO Publishing, 2010, p. 92–93 (we also read that source) en.wikipedia.org
  2. Wikipedia, "Borneo shark" (CC BY-SA 4.0), which cites: "Carcharhinus borneensis", 2021; Dulvy, N.K., Bin Ali, A., Derrick, D., Dharmadi & Fahmi., "Carcharhinus borneensis", IUCN Red List of Threatened Species, 2021, p. e.T39367A124407121; "Descriptions of New Sharks and Rays from Borneo", CSIRO Marine and Atmospheric Research, 2010, p. 17–28; Last, P.R., "Sharks and Rays of Borneo", CSIRO Publishing, 2010, p. 92–93 (we also read that source) en.wikipedia.org
  3. IUCN Red List assessment (category and year as redistributed in GBIF's IUCN Red List checklist). IUCN Red List terms: fact (category, year) cited, no text reused. iucnredlist.org
  4. Wikipedia, "Borneo shark" (CC BY-SA 4.0), which cites: "Descriptions of New Sharks and Rays from Borneo", CSIRO Marine and Atmospheric Research, 2010, p. 17–28; Compagno, L.J.V., "Sharks of the World: An Annotated and Illustrated Catalogue of Shark Species Known to Date", Food and Agricultural Organization, 1984, p. 458–459 (we also read that source) en.wikipedia.org
  5. Wikipedia, "Borneo shark" (CC BY-SA 4.0), which cites: Garrick, J.A.F. (1982). Sharks of the genus Carcharhinus. NOAA Technical Report, NMFS CIRC 445.; Compagno, L.J.V., "Sharks of the Order Carcharhiniformes", Princeton University Press, 1988, p. 319–320 (original not read by us) en.wikipedia.org
  6. Wikipedia, "Borneo shark" (CC BY-SA 4.0), which cites: "Descriptions of New Sharks and Rays from Borneo", CSIRO Marine and Atmospheric Research, 2010, p. 17–28 (original not read by us) en.wikipedia.org

Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Borneo shark (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.

Related entries

Same family (Carcharhinidae)

Atlantic sharpnose shark Rhizoprionodon terraenovaeBorneo broadfin shark Lamiopsis tephrodesBrazilian sharpnose shark Rhizoprionodon lalandiiBroadfin shark Lamiopsis temminckiiGanges shark Glyphis gangeticus

Named in this entry

Scoliodon

More in Reef sharks

Requiem sharkAbdouniaBlue sharkRiver sharkWhitetip reef sharkCarcharhinusAustralian blacktip sharkBignose sharkBlacknose sharkBlackspot sharkBlacktip reef sharkBlacktip shark

Elsewhere in Sharks

Greenland shark · Dogfish sharks and relativesSawshark · Dogfish sharks and relativesHammerhead shark · Hammerhead sharksGreat white shark · Mackerel sharksBasking shark · Mackerel sharksMegalodon · Mackerel sharks

Test yourself

Three questions drawn from this entry’s sources. Pick an answer to check it.

1. What is the IUCN Red List category of the Borneo shark?

Correct.

Not quite. The answer is Critically Endangered.

From the source: “The International Union for Conservation of Nature last assessed this species as Critically Endangered.”

2. To which genus does the Borneo shark belong?

Correct.

Not quite. The answer is Carcharhinus.

From the source: “The Borneo shark (Carcharhinus borneensis) is a species of requiem shark, and part of the family Carcharhinidae.”

3. To which biological family does the Borneo shark belong?

Correct.

Not quite. The answer is Carcharhinidae.

From the source: “The Borneo shark (Carcharhinus borneensis) is a species of requiem shark, and part of the family Carcharhinidae.”

Answers checked against the source article

Sources

Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.

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