Indian swellshark
| Indian swellshark | |
|---|---|
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Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Division: | Selachii |
| Order: | Carcharhiniformes |
| Family: | Scyliorhinidae |
| Genus: | Cephaloscyllium |
| Species: | C. silasi
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| Binomial name | |
| Cephaloscyllium silasi (Talwar, 1974)
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| Range of the Indian swellshark | |
The Indian swellshark (Cephaloscyllium silasi) is a catshark of the family Scyliorhinidae found in the western Indian Ocean near Quilon, India and Sauqira Bay, Oman.[2] Specimens caught as bycatch near North Sentinel Island of the Andaman and Nicobar Islands have been genetically identified as Indian swellsharks, expanding its known range to the Andaman Sea.[3] It grows to about 36 cm in length, and can expand its body by taking in air or water to make it appear larger to predators.
The shark is considered to be critically endangered. It is threatened by fishing pressure as it is caught incidentally by deep-water trawling practices, which occur throughout its entire known range.[1]
Etymology
[edit]Cephaloscyllium comes from the words cephalus, meaning head (from the Greek kephalḗ), and scyllium, meaning small dog (from the Greek skýlion). The specific name, silasi, was given in honour of Sri Lankan-born Indian ichthyologist Eric Godwin Silas.[4]
Description
[edit]The Indian swellshark has a light brown dorsal surface striped with seven dark brown bands, and a pale brown underside. Juvenile sharks appear light brown, similar to the adult but more faded in colour. They have a flat, rounded head, a stout body, five gill slits, and slit-like eyes.[5]
Suspected to be a 'dwarf' species of Cephaloscyllium, the Indian swellshark is estimated to reach a maximum of 50.0 cm in total length. Length at maturity of males is reported as 36.7 cm, while an examined female was measured to be 45.0 cm long.[5][6]
Biology
[edit]The Indian swellshark is a single oviparous species. The egg case is described as of medium length (85.1–86.2 mm) with long, convoluted tendrils on the posterior and anterior sides. An examined gravid female carried one egg case in each uterus, containing visible embryos.[5]
A study on the Sarawak pygmy swellshark revealed that the shark has a unique reproductive mechanism termed "sustained single oviparity", wherein pregnant females always have a singular egg case, and retain it until a certain stage of embryonic development. A comparison with the studied female Indian swellshark suggests that the species may exhibit the same reproductive mechanism, based on the presence of a single embryo in each oviduct and the relatively advanced size of such.[7]
Ecology
[edit]The Indian swellshark is a marine, bathydemersal shark, found on the continental slope at a depth range of 100–500 m.[3][5]
The examined stomach of an Indian swellshark contained crustaceans and cephalopods.[5]
References
[edit]- ^ a b Dulvy, N.K.; Bineesh, K.K.; Bown, RMK, Cheok, J.; Dharmadi.; Sherman, C.S. (2020). "Cephaloscyllium silasi". IUCN Red List of Threatened Species. 2020: e.T161591A124511862. doi:10.2305/IUCN.UK.2020-3.RLTS.T161591A124511862.en. Retrieved 18 November 2021.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Talwar, P.K. (1972). "On a new bathypelagic shark, Scyliorhinus (Halaelurus) silasi (Fam. Scyliorhinidae) from the Arabian Sea" (PDF). Journal of the Marine Biological Association of India. 14 (2): 779–783.
- ^ a b Kumar, R.R.; Venu, S.; Bineesh, K.K.; Basheer, V.S. (2016). "New biogeographic data and DNA barcodes for the Indian swellshark, Cephaloscyllium silasi". Acta Ichthyologica et Piscatoria. 46 (2): 131–135. doi:10.3750/AIP2016.46.2.10.
- ^ Christopher Scharpf & Kenneth J. Lazara, eds. (9 March 2023). "Family SCYLIORHINIDAE Gill 1862 (Catsharks)". The ETYFish Project Fish Name Etymology Database. Christopher Scharpf and Kenneth J. Lazara. Archived from the original on 22 May 2025. Retrieved 22 May 2025.
- ^ a b c d e Akhilesh, K.V.; Bineesh, K.K.; Mishra, S.S.; Ganga, U.; Pillai, N.G.K. (2014). "Notes on the Indian swellshark, Cephaloscyllium silasi (Scyliorhinidae: Carcharhiniformes) from deep waters off the west coast of India". Marine Biodiversity Records. 7: e25. Bibcode:2014MBdR....7E..25A. doi:10.1017/S1755267214000141. ISSN 1755-2672.
- ^ Compagno, L.J.V (1988). Sharks of the order Carcharhiniformes. Princeton, N: Princeton University Press. p. 486.
- ^ Nakaya, Kazuhiro; White, William T.; Ho, Hsuan-Ching (2020-07-23). "Discovery of a new mode of oviparous reproduction in sharks and its evolutionary implications". Scientific Reports. 10 (1): 12280. Bibcode:2020NatSR..1012280N. doi:10.1038/s41598-020-68923-1. ISSN 2045-2322. PMC 7378224. PMID 32703969.
- Froese, Rainer; Pauly, Daniel (eds.). "Cephaloscyllium silasi". FishBase. may 2006 version.