Additional jellyfish expected as the sea warms this summer

Jellyfish are likely to be a common thing this summer, and one of the main causes is warmer-than-usual sea temperatures, Niwa says.

Of 223 species of Scyphozoa jellyfish known worldwide, 22 were found in New Zealand waters, said Niwa marine biologist Diana Macpherson.

And while most jellyfish stings in the seas of this country are not serious, invertebrates should be avoided whenever possible.

In the case of a jellyfish sting, the area should be rinsed with seawater to remove the stinging cells, and any tentacles that may be attached should be carefully pulled out, Macpherson said. “Then apply heat to relieve pain and deactivate the poison.”

READ MORE:
* Massive purple jellyfish shocks 30-year-old walker on Auckland beach
* Huge lion’s mane jellyfish washes up on Auckland beach
* Giant jellyfish and swarms of salps wash up in Wellington’s waters during the summer
* Lion’s mane jellyfish seen in Marlborough Sounds
* Dangerous jellyfish appear in Wellington Harbor
* Lion’s mane jellyfish return to Nelson’s waters

It is a common misconception that urine should be used to relieve a sting. It could even make the pain worse, since there was no way to know its pH and chemical composition.

An increase in the species, known as jellyfish bloom, occurs when the water temperature rises, making more food available.

“The number of jellyfish increases as a result, then prevailing winds and currents can gather them into dense groups and leave them stranded on beaches,” Macpherson said.

Scientists have found that human impacts like overfishing, pollution, and warming oceans are compounding the problem of jellyfish blooms.

Jellyfish have no hearts, brains, or bones, but they capture their prey, using stinging cells called nematocysts that function a bit like harpoons containing venom, and eat them.

Species that can be seen on New Zealand beaches include:

Lion’s mane (Cyanea rosea) – The largest species of jellyfish seen in our waters with a bell that can reach two meters in diameter and tentacles that can grow up to 36m long. It is pinkish-brown on top of its bell and creamy to off-white on its margin, and has four ruffled oral arms, eight groups of tentacles, and each group has more than 100 individual tentacles. They occasionally swarm in large numbers and produce a painful sting.

Moon jellyfish (Aurelia) – This one has a disc-shaped transparent whitish ghostly bell with a scalloped margin bearing hundreds of short, thin tentacles. They are capable of limited movement, mainly drifting with the current. They are typically up to 25 cm in diameter, potentially up to 40 cm or more. It can be recognized by its four purple-pink crescent-shaped gonads that are easily seen through the top of the bell. They have little or no stingers. This species can occasionally flourish in large swarms, posing a potential problem for salmon farms, as they can cause massive fish kills from asphyxia from jellyfish mucus and irritation from their stinging cells.

Spotted jellyfish (Desmonema gaudichaudi) – Known for dark moles on their bodies and 30 cm long tentacles. Like the lion’s mane, it has four long curtains of oral arms, and its long tentacles are arranged in eight groups that hang straight from the inside of the bell (rather than the margin) and produce a painful sting.

You can find more information about jellyfish on Niwa’s website.