Hemiscyllium

Hemiscyllium is a genus of sharks in the family Hemiscylliidae.

Hemiscyllium
Hemiscyllium ocellatum
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Orectolobiformes
Family: Hemiscylliidae
Genus: Hemiscyllium
Species

See text

Overview

The Hemiscyllium genus of the Hemiscylliidae shark family go by many names including walking sharks,[1] bamboo sharks, and Epaulette sharks. These small, nocturnal, benthic dwelling swimmers have evolved to be able to 'walk', or use their fins to propel themselves over rocks, into pools, or into small crevices in their habitats. [2][3] Recent research from marine biologists at the School of Biomedical Sciences at the University of Queensland in Australia [1] has determined that this shark genus, Hemiscyllium, is the most recent branch which split off from its closest relative, Chiloscyllium, around 44 million years ago. [2] This genus is confined to tropical waters off Australia, Papua New Guinea, and Indonesia, but an individual from this genus, possibly representing an undescribed species, has been photographed at the Seychelles.[4] They have short snouts with the nostrils placed almost at the tip, and well-elevated eyes and supraorbital ridges. The mouth is closer to the tip of the snout than the eyes and lacks the connecting dermal fold across the chin. The pectoral and pelvic fins are thick and heavily muscular. Either a black hood on the head or a large black spot on the sides of the body is present,[5] though juveniles often are strongly marked with dark spots/bars. This shark family can survive around two hours out of water without any internal damage, can tolerate higher levels of CO2 and are hypoxia and anoxia tolerant. [6]

Adaptations

Epaulette sharks live in shallow waters near reefs, tidepools or islands and are currently only found in the Western South Pacific. [7] Utilizing their habitat, the epaulette shark uses its fins to crawl inside small crevices or holes while hunting for small prey and escaping larger predators. [8] These sharks have another defense mechanism, their black eye or hood. Each shark species in the Hemiscyllium genus has a distinct black 'eye' or hood behind its pectoral fin to deter other predators by giving the appearance of a very large eye. [7] the discovery of the nine species is relatively new and the best way to determine species from another species is by looking at their color pattern as well as location. [7] Neonate and juvenile epaulette sharks are born with lighter color markings and slightly different patterns but as the shark matures, the color tends to darken, and the pattern shifts to mimic its environment. [7] This suggests that Epaulette shark's habitat changes as the shark matures. More research needs to be done on juveniles and neonates to accurately assess their ontology. In addition, more research needs to be conducted to better understand this shark genus.

List of species

Nine recognized species are in this genus:[9][10]

References
  1. "Walking sharks discovered in the tropics". UQ News. The University of Queensland. 2020-01-21.
  2. Dudgeon, Christine L.; Corrigan, Shannon; Yang, Lei; Allen, Gerry R.; Erdmann, Mark V.; Fahmi; Sugeha, Hagi Y.; White, William T.; Naylor, Gavin J. P. (2020). "Walking, swimming or hitching a ride? Phylogenetics and biogeography of the walking shark genus Hemiscyllium". Marine and Freshwater Research. 71 (9): 1107. doi:10.1071/mf19163. ISSN 1323-1650.
  3. Allen, Gerald R.; Erdmann, Mark V.; White, William T.; Fahmi; Dudgeon, Christine L. (2016-11-02). "Review of the bamboo shark genus Hemiscyllium (Orectolobiformes: Hemiscyllidae)". Journal of the Ocean Science Foundation. 23: 51–97. doi:10.5281/zenodo.164197.
  4. Debelius, H. (1993). Indian Ocean Tropical Fish Guide. Aquaprint Verlags GmbH. ISBN 3-927991-01-5
  5. Compagno, Leonard J.V. (1984). Sharks of the World: An Annotated and Illustrated Catalogue of Shark Species Known to Date. Rome: Food and Agriculture Organization. ISBN 92-5-101384-5.
  6. Porter, Marianne E; Hernandez, Andrea V; Gervais, Connor R; Rummer, Jodie L (2022-07-27). "Aquatic Walking and Swimming Kinematics of Neonate and Juvenile Epaulette Sharks". Integrative and Comparative Biology. 62 (6): 1710–1724. doi:10.1093/icb/icac127. ISSN 1540-7063.
  7. Allen, Gerald R.; Erdmann, Mark V.; White, William T.; Fahmi; Dudgeon, Christine L. (2016-11-02). "Review of the bamboo shark genus Hemiscyllium (Orectolobiformes: Hemiscyllidae)". Journal of the Ocean Science Foundation. 23: 51–97. doi:10.5281/zenodo.164197.
  8. Dudgeon, Christine L.; Corrigan, Shannon; Yang, Lei; Allen, Gerry R.; Erdmann, Mark V.; Fahmi; Sugeha, Hagi Y.; White, William T.; Naylor, Gavin J. P. (2020). "Walking, swimming or hitching a ride? Phylogenetics and biogeography of the walking shark genus Hemiscyllium". Marine and Freshwater Research. 71 (9): 1107. doi:10.1071/mf19163. ISSN 1323-1650.
  9. Froese, Rainer and Pauly, Daniel, eds. (2013). Species of Hemiscyllium in FishBase. April 2013 version.
  10. Allen, G.R.; Erdmann, M.V. & Dudgeon, C.L. (2013). "Hemiscyllium halmahera, a new species of Bamboo Shark (Hemiscylliidae) from Indonesia" (PDF). Aqua, International Journal of Ichthyology. 19 (3): 123–136.
  11. Allen, Gerald R. & Erdmann, Mark V. (2008). "Two new species of bamboo sharks (Orectolobiformes: Hemiscylliidae) from Western New Guinea" (PDF). Aqua (Miradolo Terme). 13 (3–4): 93–108.
  12. Allen, Gerald R. & Dudgeon, Christine L. (2010). "Hemiscyllium michaeli, a new species of Bamboo Shark (Hemiscyllidae) from Papua New Guinea". Aqua International Journal of Ichthyology. 16 (1): 19–30.
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