One of New Zealand's largest spiders measures up to 12 centimetres across and is big enough that it feeds on wētā.

Its eyes shine so brightly it can be seen up to 20 metres away in a headlight beam.

But if you're an arachnophobe, worry not. Your chance of coming face to face with one is slim.

COLIN MISKELLY/TE PAPA A male Rangatira spider snacks on a Novoplectron wētā at night.

The home of the Rangatira spider – Dolomedes schauinslandi – is Rangatira Island and two other islands, which are part of the Chatham Islands.

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COLIN MISKELLY/TE PAPA A female Rangatira spider guards its silken nest on Rangatira Island.

A good indicator of how big the spiders are is that people are known to have declined to visit the island because of them, according to Te Papa natural environment curator Colin Miskelly.

Miskelly spent a month on Rangatira Island volunteering for the Department of Conservation.

Although the team was mainly focused on the black robin and Chatham petrel recovery programme, Miskelly had time to get up close with the spiders.

COLIN MISKELLY/TE PAPA The northern slopes of Rangatira Island, with Pitt Island in the distance at top left.

They're oversized relatives of the nursery web spider found on the New Zealand mainland.

Rangatira spiders are more easily found at night time when they hunt on tree trunks and the forest floor for their preferred prey – wētā, Miskelly wrote.

​They don't use webs to catch wētā – they pounce.

Like the nursery web spider, the females also make a silk nest to guard their young. Males are slightly smaller than females and more brightly coloured.

Despite being endemic to the Chatham Islands, they're only found on three islands.

Miskelly said despite it never having been observed, it was assumed mice had hunted the spiders to extinction on Pitt Island, the second largest of the Chatham Islands.