Warning as toxic sea slugs wash up on Bay of Plenty beaches

A blue sea slug at Mangawhai Heads surf beach this week. Photo / Kathie Alcorn

There are reports of a strange-looking blue sea slug washing up on beaches along the Bay of Plenty coastline - and people are asked to avoid them.

Glaucus atlanticus isn't toxic but it stores stinging nematocysts (cells in the tentacles of jellyfish) within its own tissues as a defence mechanism.

Bay of Plenty Regional Council environmental scientist Dr Josie Crawshaw said the slugs eat nasties like bluebottles and store their stinging cells.

People should avoid the glaucus atlanticus sea slug. Photo / Supplied

"Treat them like you would a bluebottle washing up: don't touch them in case they sting you, it can be painful," she said.

"Keep pets away, it would irritate them or if they had a lot [of stings] I wouldn't say it would be toxic but would have some negative side effects on the animal."

The blue sea slug is commonly found throughout the world, usually in the mid-subtropical area, and often washes up along the Northland coast.

A glaucus atlanticus sea slug that washed up in Mount Maunganui in 2007. Photo / File

Crawshaw said it was unusual to have them wash up in the Bay of Plenty but it showed the influence the east Auckland current had on our coast.

"We've had quite a long period of these strong onshore winds and this species is a drifter, it floats around in the water column and is totally at the mercy of the elements," she said.

There have been reports of them washing up from Ōhope, Waiotahi,and Pāpāmoa Beach.

One of the sea slugs washed up on Mount Maunganui's main beach in March 2007.

At the time, a marine incursion investigator from the Ministry of Agriculture and Forestry said they wouldn't label them as dangerous. However, the investigator did advise against picking them up.

The regional council took to Facebook yesterday to alert Bay of Plenty residents that the slugs had been found along the coast.

They asked people who spotted them to comment on the post with the time and location they saw the slugs.