Bigeye sand tiger

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Bigeye sand tiger

Least Concern  (IUCN 3.1)[1]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Subdivision: Selachimorpha
Order: Lamniformes
Family: Odontaspididae
Genus: Odontaspis
Species:
O. noronhai
Binomial name
Odontaspis noronhai
(Maul, 1955)
Confirmed (dark blue) and suspected (light blue) range of the bigeye sand tiger[2]
Synonyms

Carcharias noronhai Maul, 1955

The bigeye sand tiger (Odontaspis noronhai) is an extremely rare species of mackerel shark in the family Odontaspididae, with a possible worldwide distribution. A large, bulky species reaching at least 3.6 m (12 ft) in length, the bigeye sand tiger has a long bulbous snout, large orange eyes without nictitating membranes, and a capacious mouth with the narrow teeth prominently exposed. It can be distinguished from the similar smalltooth sand tiger (O. ferox) by its teeth, which have only one lateral cusplet on each side, and by its uniformly dark brown color.

Inhabiting

viviparous with oophagous embryos like in other mackerel shark species. This shark is caught incidentally by commercial fisheries
, though so infrequently.

Taxonomy and phylogeny

Head

The first known bigeye sand tiger was a female 1.7 m (5.6 ft) long caught off

sand tiger shark family. When the Odontaspis came to be recognized as a valid genus separate from Carcharias, the bigeye sand tiger was reassigned as well given its resemblance to the smalltooth sand tiger (O. ferox).[2] Until more specimens were examined in the 1980s, some authors speculated that this species represented an extreme variant of the smalltooth sand tiger. Other names for this shark include black sand tiger, oceanic sand tiger, and bigeye ragged-tooth shark.[2][4]

Whether the bigeye and smalltooth sand tigers belong in the same family as the superficially similar

sister species relationship between O. noronhai and O. ferox but not a clade consisting of Odontaspis and Carcharias. Instead, Odontaspis was found to be closer to the crocodile shark (Pseudocarcharias kamoharai), suggesting that it and Carcharias should be placed in separate families.[5]

Description

The teeth differ in shape in the bigeye sand tiger and in other, similar species.
Lateral teeth
Central teeth

With its heavyset body, conical bulbous snout, and large mouth filled with protruding teeth, the bigeye sand tiger looks much like the better-known sand tiger shark. The large eyes lack

cusp flanked by one smaller cusplet on each side; this contrasts with the smalltooth sand tiger, which has two or three lateral cusplets on each side. There are five pairs of gill slits.[2]

The

gill arches.[2][8] The largest male and female specimens measured 3.6 and 3.3 m (12 and 11 ft) long respectively.[9]

Distribution and habitat

Though extremely rare, the bigeye sand tiger has been reported from scattered locations around the world, suggesting a wide and possibly

temperate oceanic waters.[10] Most known specimens have come from the Atlantic, where it has been found off Madeira, southern Brazil, Texas, eastern Florida, and the Mid-Atlantic Ridge.[6] The only evidence for its presence in the Indian Ocean is a set of jaws that may have originated from the Seychelles, though the South China Sea is another possibility.[4] The existence of this species in the Pacific Ocean was first suspected in 1970 from teeth recovered from bottom sediments, which was confirmed over a decade later by captures from the Marshall Islands and Hawaii.[2][7]

The bigeye sand tiger has been caught between the depths of 60 and 1,000 m (200 and 3,280 ft). Some were recorded over

epipelagic zone at night to feed. In Brazilian waters, bigeye sand tigers are only captured in spring, hinting at some type of seasonal migratory movement.[2]

Biology and ecology

One account of a bigeye sand tiger that had been caught alive noted that it behaved very aggressively, thrashing and snapping violently in and out of the water.

mature sexually at somewhere between 2.2 and 3.2 m (7.2 and 10.5 ft) long, while females mature at around 3.2 m (10 ft) long.[2] No information is available on growth or aging.[6]

Human interactions

Because the bigeye sand tiger is encountered so infrequently, it has no commercial importance.

Data Deficient, citing a lack of biological and population data.[10] Since 1997, the National Marine Fisheries Service (NMFS) has prohibited the taking of this species in United States waters.[6][8]

References

  1. doi:10.2305/IUCN.UK.2019-1.RLTS.T39336A2899894.en
    . Retrieved 18 November 2021.
  2. ^
    ISBN 92-5-104543-7
    .
  3. ^ Maul, G.E. (1955). "Five species of rare sharks new for Madeira including two new to science". Notulae Naturae (Academy of Natural Sciences of Philadelphia). 279: 1–14.
  4. ^ a b c Martin, R.A. "Biology of the Bigeye Ragged-Tooth Shark (Odontaspis noronhai)". ReefQuest Centre for Shark Research. Retrieved May 15, 2013.
  5. ISBN 978-1-4398-3924-9
    .
  6. ^
    ISBN 9780195392944
    .
  7. ^
    S2CID 198499661
    .
  8. ^ a b c Kerstetter, D.W.; Taylor, M.L. (2008). "Live release of a bigeye sand tiger Odontaspis noronhai (Elasmobranchii: Lamniformes) in the western North Atlantic Ocean". Bulletin of Marine Science. 83 (3): 465–469.
  9. ^ Froese, R.; Pauly, D., eds. (2011). "Odontaspis noronhai, Bigeye sand tiger shark". FishBase. Retrieved May 15, 2013.
  10. ^ a b "The IUCN Red List of Threatened Species". IUCN Red List of Threatened Species. Retrieved 2018-11-17.

External links

Wikimedia Commons has media related to Odontaspis noronhai.

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