New Zealand is often perceived as a land entirely free of snakes. While the country does not have any native land snakes, its marine environment occasionally hosts venomous sea snakes. These oceanic visitors arrive due to natural forces, leading to rare encounters along the coastline.
Absence of Native Land Snakes
New Zealand’s lack of native land snakes is primarily due to its ancient geological history and prolonged isolation. The landmass separated from Gondwana approximately 85 million years ago, long before snakes had diversified globally. This early separation, combined with its continued isolation in the vast Pacific Ocean, created a natural barrier that prevented land snake species from colonizing the islands.
The country’s ecosystem evolved without these predators, leading to unique wildlife, such as ground-nesting birds without natural defenses. Strict biosecurity laws maintain this snake-free status, preventing the introduction of non-native species. While snakes can sometimes arrive via cargo, authorities intercept and remove them to protect New Zealand’s vulnerable native fauna.
Occasional Presence of Marine Snakes
Despite the absence of land snakes, New Zealand’s waters are occasionally visited by highly venomous marine snakes. These accidental visitors are carried by ocean currents from tropical habitats. The most commonly sighted species is the yellow-bellied sea snake (Hydrophis platurus), an aquatic snake identified by its distinct black upper body and yellow underside. Around 6 to 10 yellow-bellied sea snakes are reported annually, primarily along the North Island’s northeast coast, though they have been found as far south as Cook Strait.
Sea kraits also make rare appearances, including the yellow-lipped sea krait (Laticauda colubrina) and the Saint Giron’s sea krait. These semi-aquatic snakes spend time in the ocean and on land to drink fresh water and lay eggs. They possess potent neurotoxic venom capable of causing respiratory and cardiovascular collapse. However, they are generally docile, and there are no recorded sea snake bites in New Zealand. Most marine snakes washing ashore are unwell due to colder water temperatures, as New Zealand is at the southern edge of their range.
What to Do If You See a Marine Snake
Encountering a marine snake in New Zealand requires caution. Maintain a safe distance and never attempt to touch, handle, or move the snake, even if it appears docile or unwell. Direct contact with these highly venomous animals poses a risk.
The Department of Conservation (DOC) classifies sea snakes and kraits as native species under the Wildlife Act 1953 because they arrive naturally via ocean currents. It is illegal to harm, harass, or possess a sea snake without a permit. If you observe a marine snake, whether alive or deceased, immediately report the sighting to the DOC hotline: 0800 DOC HOT (0800 362 468). Providing details such as the location and, if possible, photographs, assists authorities.