Annulated sea snake (Hydrophis cyanocinctus)

Description

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Annulated sea snake fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Annulated sea snake description

Sea snakes are amongst the most venomous of the world’s snakes, and are highly adapted to life at sea, being the most completely marine of all reptiles and never voluntarily coming ashore ^{(3) (4) (5)}. All possess a flattened, paddle-like tail for swimming, as well as valved nostrils, which can be closed when the snake is underwater. Sea snakes lack the expanded belly scales that most other snakes use for moving on land ^{(2) (3) (4)}. The body of the annulated sea snake (Hydrophis cyanocinctus) is variable in colouration, but usually bears 50 to 75 black bands or rings on a yellow or olive background ^{(3) (6)}, the bands being broader towards the upper surface of the body and usually tapering to a point on the flanks. The species is one of the longest of all sea snakes ⁽²⁾, and the female is larger than the male ⁽⁶⁾.

Also known as

bluebanded sea snake, blue-banded sea snake.

French

Hydrophide A Bandes Bleues.

Size

Length: up to 275 cm ⁽²⁾

Annulated sea snake biology

Little information is available on the biology of the annulated sea snake. Other sea snakes have been recorded diving to depths as great as 100 metres, and remaining underwater for up to 2 hours before surfacing to breathe ⁽³⁾. Like other sea snakes, it is likely that the powerful venom is used to overcome prey, which in this species includes eels and other elongate fish ⁽²⁾, and it may also have a secondary role in aiding digestion ^{(3) (5)}. Studies in captivity suggest prey is located by movement-sensitive receptors in the skin, rather than using vision, with captive individuals able to catch fish in total darkness ^{(6) (7)}.

All sea snakes give birth to live young ^{(3) (4)}. In captivity, the annulated sea snake has been shown to give birth, at night, during January and February. Three to five young are usually produced, and measure around 43 centimetres at birth, although females are larger than males even at this young age ^{(6) (7)}.

Annulated sea snake range

The annulated sea snake is reported to occur in the Indian Ocean, including in the Arabian Gulf, east to Thailand, Malaysia and the Philippines, and in the Western Pacific Ocean, the South China Sea and East China Sea ^{(1) (2) (3)}.

Annulated sea snake habitat

The annulated sea snake usually inhabits warm, shallow waters over reefs, seagrass or sand ⁽³⁾.

Annulated sea snake status

The annulated sea snake is classified as Least Concern (LC) on the IUCN Red List ⁽¹⁾.

Annulated sea snake threats

Very little is known about the conservation status of this and other sea snakes ⁽³⁾. The annulated sea snake is believed to be relatively common, but has been reported to occur as bycatch in commercial trawleries ⁽⁷⁾. The extent of this threat is unknown, as is the extent to which other threats to marine ecosystems, such as overfishing, reef destruction, pollution and climate change, may impact this species. Many sea snakes are exploited for the skins, organs and meat ⁽²⁾, but it is not known whether this poses a threat to the annulated sea snake.

Annulated sea snake conservation

Research into most sea snakes has been minimal ⁽³⁾. Most sea-snake fisheries in the Indian and Pacific Oceans are unregulated, and their impacts are virtually unknown ⁽²⁾. Despite some species being taken in large numbers, no sea snakes are listed under the Convention on International Trade in Endangered Species (CITES) ⁽⁸⁾.

Environment Agency - Abu Dhabi is a principal sponsor of ARKive. EAD is working to protect and conserve the environment as well as promoting sustainable development in the Emirate of Abu Dhabi.

View information on this species at the UNEP World Conservation Monitoring Centre.

Find out more

Find out more about the annulated sea snake and other sea snake species:

• Carpenter, K.E. and Niem, V.H. (2001) The Living Marine Resources of the Western Central Pacific. Volume 6: Bony Fishes Part 4 (Labridae to Latimeriidae), Estuarine Crocodiles, Sea Turtles, Sea Snakes and Marine Mammals. Food and Agriculture Organisation of the United Nations, Rome. Available at:
  ftp://ftp.fao.org/docrep/fao/009/y0870e/y0870e65.pdf
• Halliday, T. and Adler, K. (2002) The New Encyclopedia of Reptiles and Amphibians. Oxford University Press, Oxford.

For more information on the conservation of snakes and other reptiles:

• International Reptile Conservation Foundation:
  http://www.ircf.org

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Glossary

Bycatch

In the fishing industry, the part of the catch made up of non-target species.

References

1. IUCN Red List (April, 2011)
   http://www.iucnredlist.org/
2. Carpenter, K.E. and Niem, V.H. (2001) The Living Marine Resources of the Western Central Pacific. Volume 6: Bony Fishes Part 4 (Labridae to Latimeriidae), Estuarine Crocodiles, Sea Turtles, Sea Snakes and Marine Mammals. Food and Agriculture Organisation of the United Nations, Rome. Available at:
   ftp://ftp.fao.org/docrep/fao/009/y0870e/y0870e66.pdf
3. Hellyer, P. and Aspinall, S. (2005) The Emirates: A Natural History. Trident Press Limited, London.
4. Halliday, T. and Adler, K. (2002) The New Encyclopedia of Reptiles and Amphibians. Oxford University Press, Oxford.
5. Vine, P. (1996) Natural Emirates: Wildlife and Environment of the United Arab Emirates. Trident Press, London.
6. Karthikeyan, R. and Balasubramanian, T. (2008) Feeding and reproductive behaviour of captive sea snakes Hydrophis cyanocinctus. Applied Herpetology, 5(1): 75 - 80.
7. Karthikeyan, R., Vijayalakshmi, S. and Balasubramanian, T. (2008) Feeding and parturition of female annulated sea snake Hydrophis cyanocinctus in captivity. Current Science, 94(5): 660 - 664.
8. CITES (July, 2009)
   http://www.cites.org