Sea Snakes or Coral Reef Snake scientific name is Hydrophiinae. Mainly located around the tropical areas of The Indian and Pacific Oceans there are few divers who have dived with them can say they were not a little fearful. They vary from 50cm to 2m as adults depending on species, most have a dark top, light under belly and often have rings of black or white around their bodies. Wikipedia claims they do not exist in The Red Sea, but I definitely dived on a reef about ten years ago that they did inhabit. Please comment if you have dived the Red Sea with them too.
Adapted to the aquatic environment these vertebrates still require air to breathe. Their lungs run pretty much the length of their body. There are less than fifty species but most are considered placid to divers only attacking if provoked. Their spines have adapted so their rear is more of a flattened paddle fin.
They are certainly venomous and if bitten you should seek medical attention as soon as possible. Compared to land snakes they have relatively short fangs which are unlikely to penetrate a medium thickness wetsuit, often even if bitten they will not always release venom. A bite is usually painless so prudence is recommended if you think you may have been get medical assistance. Within twenty to thirty minutes of being bitten and venom injected you could experience headaches, breathing difficulties, droopy eyelids and muscle weakness. Luckily anti venom is available but tiger snake or polyvalent antivenin may help too. Only around 5% to 10% of bites are reported as fatal to humans.
They cannot survive on land (a couple can but not very well) and there are very few reports of divers being bitten. Most bites occur on board fishing boats where the local fishermen regularly throw them back. Reports indicate that of the few bites fishermen may receive the snakes on the whole are quite placid and rarely bite but deserve caution.
They live mainly in shallow waters, which makes sense since they need to go to the surface to breathe. Reports suggest them can stay submerged for over an hour and dive to around 100m/300ft.
Their staple diet is fish, they can swallow prey up to twice the size of their neck after immobilising them with a bite. They can also swallow eggs and crustaceans.
In breeding season they have been know to coil themselves around divers legs and hoses. It is assumed they are confused believing these to be a mate, remain calm and they will quickly realise their error and swim off. Sea snakes are curious by nature and will often swim towards divers but are rarely aggressive.
Please leave a comment here on the blog of your experience of diving with sea snakes.
Big thanks to Klaus Stiefel over at Flickr for the header image.