Hydrophis curtus explained

Hydrophis curtus, also known as Shaw's Sea Snake, short sea snake, but often includes Hydrophis hardwickii^[1] is a species of sea snake. Like most Hydrophiinae sea snakes, it is a viviparous, fully marine, and front fanged elapid that is highly venomous.^[2] It is collected for a variety of purposes including human and animal food, for medicinal purposes and for their skin.^[3]

Description

This species is characterized by a wide variation in number of ventral scales and degree of parietal scale fragmentation.^[1] Both sexes possess spiny scales along their bodies but males have more highly developed spines. This sexual dimorphism in spines may play a role in courtship or in locomotion by reducing drag.^[1]

Distribution

It is a widely distributed species and like most sea snakes is restricted to warmer, tropical waters. Its range includes:

• Persian Gulf (Oman, Bahrain, United Arab Emirates, Iran)
• Indian Ocean (Bangladesh, Pakistan, Sri Lanka, India)
• South China Sea (north to the coasts of Fujian and Shandong)
• Strait of Taiwan
• Indo-Australian Archipelago
• North Coast of Australia (Northern Territory, Queensland, Western Australia)
• Philippines (Panay)
• Pacific Ocean (Myanmar, Thailand, Indonesia, China, Japan, New Guinea)
• Andaman & Nicobar Islands, Cambodia and Singapore

Taxonomy

Originally considered to be two species of the genus Hydrophis: Hydrophis curtus and Hydrophis hardwickii. Gritis and Voris (1990) examined the morphological variation of over 1,400 specimens across its geographic range and concluded it is most likely a single species.^{[1] [3]} As is convention, the species name reverts to the first description by Shaw in 1802. DNA and morphological analysis restored its phylogenic status as a single species.^[4] An analysis of the population in 2014 found strong evidence of deep divergence and genetic isolation across the geographical range, supporting a division of the species to Indian Ocean and West Pacific groups and high likelihood of cryptic taxa within those groups.^[5]

Hydrodynamic sense

They have corpuscles (scale sensillae) concentrated on the front of their head which may be a hydrodynamic receptor.^[6] A study measuring brain response to water vibration found that L. curtus is sensitive to low amplitude (100–150 Hz) water motions.^[7] Sensing water motion is useful in locating prey, predators, or potential mates and has been demonstrated in other aquatic animals (e.g. lateral line in fish, whiskers in harbour seals).^[8]

References

Notes

Sources

• Anderson, J. 1871 A list of the reptilian accession to the Indian Museum, Calcutta, from 1865 to 1870, with a description of some new species. J. Asiat. Soc. Bengal, Calcutta, 40, part 11(1): 12–39.
• Rasmussen, A. R. & I. Ineich 2000 Sea snakes of New Caledonia and surrounding waters (Serpentes: Elapidae): first report on the occurrence of Lapemis curtus and description of new species from the genus Hydrophis. Hamadryad, 25(2): 91–99.

Notes and References

1. Gritis, P. & H. K. Voris 1990 Variability and significance of parietal and ventral scales in the marine snakes of the genus Lapemis (Serpentes: Hydrophiidae), with comments on the occurrence of spiny scales in the genus. Fieldiana Zool. n.s. (56): i-iii + 1-13.
2. Heatwole H. 1999. Sea Snakes. University of New South Wales Press, Sydney.
3. Lukoschek, V., Guinea, M., Cogger, H., Rasmussen, A., Murphy, J., Lane, A., Sanders, K. Lobo, A., Gatus, J., Limpus, C., Milton, D., Courtney, T., Read, M., Fletcher, E., Marsh, D., White, M.-D., Heatwole, H., Alcala, A., Voris, H. & Karns, D. 2010. Lapemis curtus. In: IUCN 2014. IUCN Red List of Threatened Species. Version 2014.1. www.iucnredlist.org. Downloaded on 26 June 2014
4. Sanders, K. L., Mumpuni, Lee M. S. Y. 2010 Uncoupling ecological innovation and speciation in sea snakes (Elapidae, Hydrophiinae, Hydrophiini. J. Evol. Biol. 23 (12):2685-93
5. Ukuwela . Kanishka D. B. . de Silva . Anslem . Mumpuni . Fry . Bryan G. . Sanders . Kate L. . Kate L. Sanders . Multilocus phylogeography of the sea snake reveals historical vicariance and cryptic lineage diversity . Zoologica Scripta . September 2014 . 43 . 5 . 472–484 . 10.1111/zsc.12070. 52838839 .
6. Povel, D., Kooij, J.v.d. 1997. Scale sensillae of the file snake (Serpentes: Acrochordidae) and some other aquatic and burrowing snakes. Neth. J. Zool., 47, 443–456
7. Westhoff G, Fry BG, Bleckmann H. 2005. Sea snakes (Lapemis curtus) are sensitive to low-amplitude water motions. Zoology 108, 195-200.
8. Dehnhardt G, Mauck B, Bleckmann H (1998) Seal whiskers detect water movements. Nature 394, 235-236.