Lion's mane jellyfish washes up on Whangārei Heads beach

Kennedie Mccormick, 10, provides a good scale for the size of the lion's mane jellyfish found at Urquharts Bay. Photo/Vanessa Mccormick

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Kennedie Mccormick, 10, provides a good scale for the size of the lion's mane jellyfish found at Urquharts Bay. Photo/Vanessa Mccormick

A simple walk along a Whangārei Heads beach for a Whangārei family was transformed by the discovery of a large brightly-coloured jellyfish washed up on the beach.

Vanessa Mccormick was at Urquharts Bay with her family on Saturday evening when they found a lion's mane jellyfish below the high tide mark.

"It was all purple, it had these amazing chambers inside it."

She said it was around 80cm in diameter.

"It was pretty amazing, we were blown away."

Mccormick said they had never seen one before, and it was the only one along the beach at the time.

NIWA marine biology technician Diana Macpherson said lion's mane is the largest jellyfish species found in New Zealand. Their bells are usually less than 50cm in diameter but can get up to 2m.

The lion's mane has a bright pinkish-purplish-brown, saucer-shaped bell with a mop of long tentacles and thick frilly curtains or oral arms underneath.

They are found around the entire coast of New Zealand, as far south as Campbell Island, and also along eastern Australia.

Kennedie Mccormick, 10, provides a good scale for the size of the lion's mane jellyfish found at Urquharts Bay. Photo/Vanessa Mccormick

"Jellyfish are at the mercy of strong wind and currents so it is normal for them to wash up," Macpherson said.

She said the wind or current can direct them to a harbour, bay or beach where they become stranded.

Macpherson said the lion's mane can deliver painful stings through their tentacles, even after being stranded onshore. For some people, stings may result in an allergic reaction.

She said the recommended treatment for minor stings is to vigorously flush the stung area with lots of seawater, not fresh water, to rinse away the tentacles and stinging cells. Vinegar may also help, but there is some debate about this.

"Pluck off any clinging tentacles with tweezers. Scraping them off or rubbing with sand triggers any active stinging cells to release more venom, so take care when removing tentacles."

The final step is to apply heat, as it permanently inactivates the venom.