Sea krait

Sea kraits are a genus of venomous elapid sea snakes, Laticauda. They are semiaquatic, and retain the wide ventral scales typical of terrestrial snakes for moving on land, but also have paddle-shaped tails for swimming.[1] Sea kraits are often confused with another group of aquatic reptiles, the sea snakes. However, unlike the fully aquatic ovoviviparous sea snakes, sea kraits are oviparous and must come to land to digest prey and lay eggs.[2] They also have independent evolutionary origins into aquatic habitats, with sea kraits diverging earlier from other Australasian elapids.[3][4] Thus, sea kraits and sea snakes are an example of convergent evolution into aquatic habitats within the Hydrophiinae snakes. Sea kraits are also often confused with land kraits (genus Bungarus), which are not aquatic.

Sea krait
Laticauda colubrina
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Elapidae
Subfamily: Hydrophiinae
Genus: Laticauda
Laurenti, 1768
Species

eight, see text

Description

Sea kraits are semiaquatic, so have morphological adaptations to both land and sea. Laticauda species show traits intermediate between those of sea snakes and terrestrial elapids. They have a vertically flattened and paddle-shaped tail (similar to sea snakes) and laterally positioned nostrils and broad, laterally expanded ventral scales (similar to terrestrial elapids).[1][5][6] Their body has a striped pattern, nasal scales are separated by inter-nasals scales, and the maxillary bone extends forwards beyond the palatine bone.[2] Members of Laticauda can grow to 1.5 m (4.9 ft) long.[7]

Location

Laticauda species are found throughout the South and Southeast Asian islands spreading from India in the west, north as far as Japan, and southeast to Fiji. The species occasionally wanders south to the Eastern coast of Australia and New Zealand (Laticauda colubrina being the most common example in New Zealand), however no known locally breeding populations are known to exist in these areas.[8] Sea kraits typically live in the littoral zone of coastal waters and are semi-terrestrial, spending time ashore and in shallow waters, as well as around coral reefs.[8][9]

Diet

Laticauda species feed in the ocean, mostly eating moray and conger eels, and some squid, crabs, and fish. They have never been observed feeding on land.

Behavior

Laticauda species are often active at night, which is when they prefer to hunt. Though they possess highly toxic venom, these snakes are usually shy and reclusive, and in New Caledonia, where they are called tricot rayé ("stripey sweater"), children play with them. Bites are rare, but must be treated immediately. Bites are more likely to occur under low light conditions (night), and when the snake is roughly handled (e.g. grabbed "hard") while in the water, or having been abruptly taken from the water. When these snakes are on land, bites are extremely rare. [10] Black-banded sea kraits, numbering in the hundreds, form hunting alliances with yellow goatfish and bluefin trevally, flushing potential prey from narrow crannies in a reef the same way some moray eels do.[11][12] Sea kraits are capable of diving up to 80 m deep in a single hunting trip.[13] They have a remarkable ability to climb up vertical rocks of their coastal limestone habitats.[1]

Breeding

Laticauda females are oviparous, and they return to land to mate and lay eggs.[8] Several males form a mating ball around the female, twitching their bodies in what is termed "caudocephalic waves". Though these animals can occur in high densities in suitable locations, nests of eggs are very rarely encountered, suggesting specific nesting conditions need to be met.

Species and taxonomy

Eight species are currently recognised as being valid.[14][15]

The species L. schistorhyncha and L. semifasciata have been placed in the genus Pseudolaticauda by some authors.[17]

Nota bene: A binomial authority in parentheses indicates that the species was originally described in a genus other than Laticauda.

Parasites

Sea snakes can have parasitic ticks, occasionally with heavy infestations.[18]

References
  1. Wilson, Stephen K.; Swan, Gerry (2013). A Complete Guide to Reptiles of Australia. Chatswood, New South Wales: New Holland Publishers. p. 564.
  2. Cogger, Hal (2000). Reptiles and Amphibians of Australia. Sydney, NSW: Reed New Holland. p. 722.
  3. Pyron, R. Alexander; Burbrink, Frank T.; Colli, Guarino R.; de Oca, Adrian Nieto Montes; Vitt, Laurie J.; Kuczynski, Caitlin A.; Wiens, John J. (2011-02-01). "The phylogeny of advanced snakes (Colubroidea), with discovery of a new subfamily and comparison of support methods for likelihood trees". Molecular Phylogenetics and Evolution. 58 (2): 329–342. doi:10.1016/j.ympev.2010.11.006. ISSN 1095-9513. PMID 21074626.
  4. Keogh, J. Scott (1998-02-01). "Molecular phylogeny of elapid snakes and a consideration of their biogeographic history". Biological Journal of the Linnean Society. 63 (2): 177–203. doi:10.1006/bijl.1997.0178.
  5. Shine, R.; Shetty, S. (2001-03-01). "Moving in two worlds: aquatic and terrestrial locomotion in sea snakes (Laticauda colubrina, Laticaudidae)". Journal of Evolutionary Biology. 14 (2): 338–346. doi:10.1046/j.1420-9101.2001.00265.x. ISSN 1420-9101. S2CID 82676695.
  6. Brischoux, François; Kato, Akiko; Ropert-Coudert, Yan; Shine, Richard (2010-10-30). "Swimming speed variation in amphibious seasnakes (Laticaudinae): A search for underlying mechanisms". Journal of Experimental Marine Biology and Ecology. 394 (1–2): 116–122. doi:10.1016/j.jembe.2010.08.001.
  7. Shine, Richard; Shetty, Sohan (2002). "Activity Patterns of Yellow-Lipped Sea Kraits (Laticauda colubrina) on a Fijian Island". Copeia 2002 (1): 77-85.
  8. Gill, B.J.; Whitaker, A.H. (2014). "Records of sea-kraits (Serpentes: Laticaudidae: Laticauda) in New Zealand". Records of the Auckland Museum. 49: 39–42. ISSN 1174-9202.
  9. Wilson, Don E.; Burnie, David. (editors-in-chief) (2005) [2001]. Animal. London & New York: Dorling Kindersley. ISBN 978-0-7894-7764-4.
  10. "La Lettre de la Délégation n°202". Notes du Centre d'Études Biologiques de Chizé (UPR1934 CNRS) (CNRS DR15) (in French). 202. 2016-03-29. Archived from the original on 2017-03-23. Retrieved 2017-03-23.
  11. "Black-banded sea krait photo - Laticauda semifasciata - G78940". Archived from the original on 2012-10-08. Retrieved 2011-07-30.
  12. "Archived copy". Archived from the original on 2012-03-11. Retrieved 2015-08-18.CS1 maint: archived copy as title (link)
  13. Motani, Ryosuke (19 May 2009). "The Evolution of Marine Reptiles". Evo Edu Outreach. 2 (2): 224–235. doi:10.1007/s12052-009-0139-y.
  14. Heatwole H, Busack S, Cogger H (2005). "Geographic variation in sea kraits of the Laticauda colubrina complex (Serpentes: Elapidae: Hydrophiinae: Laticaudini)". Herpetological Monographs 19: 1-136.
  15. Cogger HG, Heatwole HF (2006). "Laticauda frontalis (de Vis, 1905) and Laticauda saintgironsi n.sp. from Vanuato and New Caledonia (Serpentes: Elapidae: Laticaudinae) – a new lineage of sea kraits?" Records of the Australian Museum 58: 245-256.
  16. Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. ISBN 978-1-4214-0135-5. (Laticauda guineai, p. 112).
  17. Kharin VE, Czeblukov VP (2006). "A new revision of the sea kraits of family Laticaudidae Cope, 1879 (Serpentes: Colubroidea)". Russian Journal of Herpetology 13: 227-241.
  18. "Sea snake parasites – 1". Tropical Research and Conservation Centre. 8 March 2011. Archived from the original on 2 April 2012. Retrieved 9 October 2017.

Further reading
  • Laurenti JN (1768). Specimen medicum, exhibens synopsin reptilium emendatam cum experimentis circa venena et antidota reptilium austriacorum. Vienna: "Joan. Thom. Nob. de Trattnern". 214 pp. + Plates I-V. (Laticauda, new genus, p. 109). (in Latin).
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