Like the movie “Jaws”… Daaaa Dum…. Daaaaa Dum… Da Da Da Dum… Da Da Da Dum…
Just when you thought it was safe to swim without getting covered in red itchy blotches, swarms of blue blubber jellyfish have returned.
These animals that have been reported in unusually large numbers this summer often swim along the ocean floor, but when it’s dawn or evening or cloudy conditions; when there’s no wind or waves, they rise to the surface.
They appear out of nowhere, first one, then two then thousands. Borne on currents they will descend on areas in huge aggregations and then disappear just as quickly.
Researchers believe the brainless animals that can feel no pain nor are able to communicate, do not aggregate deliberately rather they are brought together on the currents.
Unlike sharks with their big gnashing slashing gashing mouth, blue blubber jelly fish have hundreds of mouths that capture prey by the millions.
Hundreds of hungry mouths on the inside of the 10 or so feeding arms that hang below the bell.
These slow swimming blubbers are ravenous eaters consuming millions of plankton, fish larvae and eggs and crustaceans daily.
Instead of teeth the hundreds of mouths are armed with stinging cells that shoot barbed harpoons, which remain attached to the jellyfish mouths by tiny filaments that convey poison to the prey and draw their dinner in.
There aren’t any stinging cells around the outer rim of the bell, Griffith University jellyfish researcher Kylie Pitt says.
The researcher also says the jelly fish are constantly releasing mucous and its likely that the mucous would have stinging cells mixed in with it.
For surfers or bathers this means that you don’t have to brush against a jellyfish to be stung as there are stinging cells floating free in the water in blobs of mucous. Ms Pitt says this would only be when jellyfish are around, not when they are absent.
In Queensland the jellyfish live for the six months of spring and summer (they can live for a year down south says Ms Pitt says).The bell stage is the sexually reproductive stage during which female jellyfish can shed 20-30 million eggs each in batches.
After shedding the eggs the mouths and stomachs of the females disintegrate and Ms Pitt says its likely that the bodies sink to the bottom to be eaten by scavengers. They may leave some stinging cells behind but this is not proven.
The eggs are fertilised externally and develop quickly into free swimming planula which then attach to the sea floor.
Like tiny aliens these polyps or scyphistoma, which are also equipped with stings, feed and reproduce more polyps asexually by budding, for up to two years. When the water temperature rises they change their asexual reproduction to produce free swimming jellyfish larvae (ephyrae) which grow rapidly for three months into the adult jellyfish.
Ms Pitt says jellyfish do not carry sealice as many surfers believe. In fact she says “sea lice” is just a general term for any tiny thing (often unknown) that stings or bites in the surf. She doubts very much that the “sea lice” events on the legal anabolic steroids Gold Coast of late had anything to do with water borne stings carried in mucous of the blue blubber jellyfish, unless there are jellyfish in the area.
Anyone who has been stung this summer will be happy to hear blue blubber jellyfish are edible and have a potential export value of $18 million to the biggest market which is Japan.
Catostylus Mosaicus (the scientific name of blue blubber jellyfish) are part of a customary diet also in China, Thailand, Malaysia, Indonesia, Philippines, Hong Kong, Singapore and Korea.
Harvesting them might help reduce the blue blubbers which compete with fish for food and threaten fish populations by eating fish larvae.
So when the water is warm and the sun is low, be scared, be very scared of “Mouths” if not “Jaws”.
The stings of Catostylus Mosaicus do not cause serious injury, only redness, a minor sting and itchy feeling.