Venomous visitors pop in for a Kiwi holiday

A yellow-bellied sea snake found washed up on Baylys Beach. Photo / Michael Cunningham

They lurk among us in the water, can bite when provoked and no - we're not talking about sharks.

Beachgoers around the country are being warned to keep an eye out for yellow-bellied sea snakes, a venomous species related to the cobra that likes warm water.

Although the snakes are not endemic to New Zealand, they often wash up on North Island beaches, says Niwa principal scientist Malcolm Francis.

"They live near the surface, hang around with logs and drifting seaweed, and feed on the fish that aggregate in those areas."

All sea snakes are poisonous, but generally require a lot of provocation before they will bite. Their mouths are small with fangs set well back, making it difficult for them to bite a person.

The yellow-bellied sea snake has a pair of fangs that inject venom into its victim.

After biting its fish prey, the snake eats it head first, and has four teeth that hold the prey in place as it swallows it.

An inhabitant of the open sea which travels with surface ocean currents, the snake has a paddle-like tail that enables it to swim well.

Tauranga man Shane Davies said he saw one while fishing from a jetty with his 15-year-old son, Antony, at Plummers Pt near Omokoroa last year.

"We poked at it with a bit of stick and had to jump out of its way as it began swimming towards us," he said.

Snake expert Brian Gill, who is Auckland Museum's curator of land vertebrates, said the museum received about one report of yellow-bellied sea snakes a year.

"But that will only be the tip of the iceberg - many others will be seen and not reported."

"People should really leave them alone, and if they wanted to put one back in the water, I'd use a spade or a shovel.

"I definitely wouldn't want to pick one up by the tail."

MARINE VISITORS

* Yellow-bellied sea snakes.

* Leatherback turtle.

* Loggerhead sea turtles.

* Dolphin fish.

Source: Niwa