Japanese angelshark

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Japanese angelshark

Critically Endangered  (IUCN 3.1)[1]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Subdivision: Selachimorpha
Order: Squatiniformes
Family: Squatinidae
Genus: Squatina
Species:
S. japonica
Binomial name
Squatina japonica
Bleeker, 1858
Range of the Japanese angelshark[1]

The Japanese angelshark (Squatina japonica) is a

pectoral and pelvic fins typical of its family, and grows to 1.5 m (4.9 ft) or more in length. Its two dorsal fins are placed behind the pelvic fins, and a row of large thorns occurs along its dorsal midline. Its upper surface is cryptically patterned
, with numerous squarish dark spots on a brown background.

Feeding on

gives birth to live young, which are sustained during gestation by yolk. The litter size varies from two to 10. The Japanese angelshark is not dangerous to humans unless provoked. It is fished in large numbers and used for meat and shagreen, a type of leather
.

Taxonomy and phylogeny

The Japanese angelshark was described by Dutch

type specimen is a male 53 cm (21 in) long, collected off Nagasaki, Japan, hence the specific epithet japonica.[2][3] Other common names for this species include change angel shark, change canopy shark, Japanese angelfish, and Japanese monkfish.[4]

Using

sister species pair of the Taiwan angelshark (S. formosa) and the Indonesian angelshark (S. legnota). These Asian species are, in turn, allied with European and North African angel shark species. Molecular clock estimation suggested the Japanese angelshark lineage diverged from the rest of the Asian angelsharks some 100 million years ago during the Cretaceous.[5]

Description

The dorsal fins of the Japanese angelshark are located behind the rear tips of the pelvic fins.

The Japanese angelshark is fairly narrow-bodied and has greatly enlarged

tooth rows on either side of both jaws, separated by a gap in the middle; the teeth are small, narrow, and pointed. There are five pairs of gill slits located on the sides of the head.[3][6]

The frontmost portion of each pectoral fin forms a triangular lobe separate from the head. The outer corners of the pectoral fins are angular, and their rear tips are rounded. The pelvic fins have convex margins. The two angular

dermal denticles, and a distinctive row of large thorns is present along the midline of the back and tail. This species is light to dark brown above with a dense covering of squarish dark spots, which become finer on the fins. The underside is white with darker mottling.[3][6] Various sources give differing maximum lengths, ranging from 1.5 to 2.5 m (4.9 to 8.2 ft).[1][7]

Distribution and habitat

The Japanese angelshark is native to the cooler waters of the northwestern Pacific; its range extends from the eastern coast of

bottom-dweller found over sandy bottoms, often close to rocky reefs.[1][7]

Biology and ecology

The Japanese angelshark generally lies motionless and buried in daytime.

During the day, the Japanese angelshark mostly lies partly buried on the bottom; its complex color pattern provides

mature sexually at 80 cm (31 in) long, while male maturation size is unknown.[1]

Human interactions

The Japanese angelshark is typically inoffensive towards humans, but if disturbed, can inflict a severe bite. Across much of its range, it is a frequent catch (intentional or not) in

demersal gillnets; the meat is eaten and the rough skin is made into a type of leather called shagreen for use in wood finishing.[1][3]

Angel sharks in general are highly threatened by

critically endangered by the International Union for Conservation of Nature (IUCN). It may benefit from a ban on trawling imposed in some areas by the Chinese government, though enforcement is inconsistent.[1]

References

  1. ^
    doi:10.2305/IUCN.UK.2021-1.RLTS.T161558A134194013.en
    . Retrieved 19 November 2021.
  2. ^ Bleeker, P. (1858). "Vierde bijdrage tot de kennis der icthyologische fauna van Japan". Acta Societatis Scientiarum Indo-Neerlandicae. 3 (art. 10): 1–46.
  3. ^
    ISBN 978-92-5-101384-7
    .
  4. ^ Froese, R.; Pauly, D., eds. (2011). "Squatina japonica, Japanese angelshark". FishBase. Retrieved June 16, 2013.
  5. PMID 19647086
    .
  6. ^
    doi:10.11646/zootaxa.1551.1.2
    .
  7. ^
    ISBN 978-0-930118-18-1
    .
  8. doi:10.11646/zootaxa.2759.1.2
    .
  9. ISBN 978-1-55209-629-1
    .
  10. ^ Yamaguti, S. (1934). "Studies on the Helminth fauna of Japan. Part 4. Cestodes of fishes". Japanese Journal of Zoology. 6: 1–112.
  11. doi:10.1163/156854011x605792
    .
  12. PMID 9920318
    .
  13. S2CID 253745118
    .

External links

Wikimedia Commons has media related to Squatina japonica.

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