Sea Snakes: Graceful and Venomous

True Sea Snakes and Sea Kraits

The term 'sea snake' is applied to two groups of reptiles:

True sea snakes (family Hydrophiidae): Fully aquatic; give birth to live young in the water; cannot move effectively on land. Tails are flattened paddle-like for propulsion. Over 60 species, all in the Indo-Pacific.

Sea kraits (genus Laticauda): Semi-aquatic; come ashore to lay eggs, shed skin, and digest prey. Recognizable by banded colouring (usually alternating black and grey/white) and round (not flattened) tail. The banded sea krait (Laticauda colubrina) is the species most commonly encountered by divers in the Indo-Pacific.

Both groups are venomous — all sea snakes possess potent neurotoxic and myotoxic venoms. The venom of some species (particularly the beaked sea snake, Enhydrina schistosa) is among the most potent of any snake. The olive sea snake (Aipysurus laevis), common in Australian waters, has venom 10 times more potent than a cobra's.

The Risk to Divers

Virtually zero, in practice.

Sea snakes are docile animals. They are curious about divers (their eyesight is poor, and they may investigate a diver at close range simply to identify what they're looking at), but they bite very rarely and almost never inject venom when they do.

The key anatomical constraint: sea snake fangs are small and located at the back of a relatively small jaw. Biting through a wetsuit is difficult; delivering venom into the skin through neoprene is more difficult still.

Reported sea snake encounters from divers worldwide almost universally describe the snake as indifferent, curious, or mildly investigative — not aggressive.

Behaviour and Diving Observations

Sea snakes are air-breathing. They surface to breathe every 30 minutes to 2 hours depending on activity level and species. Underwater, they hunt fish and eels in coral crevices, using chemical sensing (flicking the tongue) to track prey. The banded sea krait hunts eels almost exclusively.

At Blue Corner in Palau and on several Maldivian reef edges, banded sea kraits are regularly encountered hunting in the reef during the day. They move with a characteristic sinuous grace — no wasted motion, no acceleration, just continuous smooth undulation — that makes them one of the more mesmerizing subjects on a reef dive.