One of many jellyfish beached this summer. PHOTO/KAREN COLTMAN
KAREN COLTMAN
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Hundreds of bluebottle jellyfish lined Castlepoint Beach on New Year’s Day and are still arriving.
Not considered ‘deadly’, a bluebottle sting can be dangerous to children, elderly people, asthmatics and people with allergies.
A sting can cause fever and respiratory distress.
Jellyfish sightings are expected to be common this summer with rising ocean temperatures the leading cause of substantial population growth.
National Institute of Water and Atmospheric Research forecasters issued a warning in December that a marine heatwave in the waters to the north of the North Island kept sea surface temperatures around the country above average since October.
Niwa marine biologist Diana Macpherson said jellyfish blooms happen when water temperatures rise, which causes an increase in the amount of food available for jellyfish to eat.
“Jellyfish numbers increase as a result, then prevailing winds and currents can gather them up into dense groups and strand them on beaches,” Macpherson said.
The research industry’s media release said scientists were discovering that overfishing, pollution and warming oceans exacerbate problematic jellyfish blooms.
But although called jellyfish, bluebottles are a colony of organisms.
They resemble jellyfish with their long dangly “stingers” but are Siphonophores. They are a colony of specialised minute individuals called zooids.
While there are about 223 species of Scyphozoa jellyfish worldwide, just 22 are found in New Zealand waters.
Jellyfish is the common name for a diverse range of jelly-like creatures including true jellyfish, hydromedusae, siphonophores, box and stalked jellyfish, comb jellies [Ctenophora] and salps [Chordata].
“They have no brain, no bones, and no heart but they reproduce, eat, and defend themselves or catch prey with astounding stinging cells called nematocysts, which work a bit like a harpoon that contains venom,” Macpherson said.
“They are all a natural part of the ecology of all oceans. They are resilient and good at what they do.”
Macpherson’s advice if stung by a jellyfish is to flush the area with seawater to remove the stinging cells, carefully pluck off any tentacles that might be stuck on, then apply heat to relieve the pain and deactivate the venom. Using urine to relieve a sting is a popular misconception and, could make the pain worse.
