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Sydney Harbour Box Jellyfish ?


gambit

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Not sure whether the mobile phone pictures are going to work out for this or not. [YEP - now finally OK!]

If they do, they are of a small jellyfish that I can only describe as a Box Jellyfish. Box shaped head, with 4 very distinct long streaming tentacles. They actively feed on small fish, worms etc attracted by wharf lights where my boat is kept at Rose Bay. Once their tentacles hit the fish, they seem to be poisoned and the tentacle then retracts it up into the box/head section, where it is quickly comsumed.

I have seen them many times over the years, probably at this time of year rather than summer.

Does anyone know what they actually are?

I had the impression that true box jellyfish (ie: sea wasps & irukandji) were only evident in Northern Australian waters, but in googling the subject and looking at pictures, the appearance is eerily similar to the irukandji variety.

Cheers,

Bob.

Edited by GAMBIT
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Hey looks alot like a irukandji !

Interesting......thought the cold water normally kills them.

Where was the pic taken?

The picture was taken last night about 6.30pm, at Rose Bay in Sydney Harbour. There were several groups of the jellyfish under different lights.

Cheers,

Bob.

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The photos are of 2 separate ones by the way. The second one already has one small shiny fish inside it's "boxhead", and another one in the grasp of a tentacle on its way up.

As I said earlier, I have seen the same type of jellyfish many times over the years, so it is not necessarily the product of a recent current. They must be a temperate species of some sort. I have done a bit more searching and found mention of some of the "CARYBDEID" variety, which look somewhat similar to these. Must be some more information around if I keep digging!

Bob.

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I've seen some swimmers in the harbour during summer that would be quite concerned to know that these are about!

Not a good sign if they are box Jellyfish!

That would make our beaches as dangerous as the far north.. aren't they deadly?

Edited by throw me a fish
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Hope those box jellies dont start coming down this part of the world, I agree it sure looks like one, and can be deadly to humans...

Bob...

as Ray has just pionted out but we do get to hear so often of unusual species of tropical fish that regularly get caught in and around sydney...

every year........so its not to far out of the realms of possibility that Jellyfish can hitch a ride down to this part of the world

on the EAC... and with all these whirlpools that have been happening of late throw this into the equation

and goodness knows....

for excample to name two instances of unusual occurance of note would be the large run of dolphin fish

that was experianced in the bass strait VIC last year that would be pushing unusually well south i would feel..

and the reverse instance being of an atlantic salmon that was caught at the entrance NSW which most likely

hailed from a damaged pen in Tasmania....

so hopefully they are just your everyday run of the mill jellyfish with a verocious appetite to fish....

and nothing more sinister...

Cheers Warnie...

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Guys I have been scuba diving and seen very similar jellies off wrecks on the Northern Beaches, around Bare Island Botany way etc...

In fact on one of my last dives at Bare Island we jumped right into a 'school' of jellies that look exactly the same as the ones in the pics. They shimmer when you touch them but no sting - at least not on the ones that we were swimming with.

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Some more Google based research, as many photos of the "jimble" look similar –

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….The research team also studied the venom of the ‘jimble’ (Carybdea rastonii), a closely-related species of jellyfish that is suspected of causing an Irukandji-like illness. In preliminary studies, the venom of Carybdea rastonii was found to exert a similar toxicity to C. barnesi, but its mechanism of action appeared to be more complex.

*******************************************************************

BUT, of course, on yet another site, they seem to discount the potency?

The Jimble, however, is not dangerous. It does sting but the venom potency is nowhere near as potent as its tropical relatives. It is the only cubozoan that occurs in the colder southern Australian waters. Occasionally it can be present in high densities in Sydney Harbour.

Distribution: Western Australia to Southern Queensland.

Habitat: Coastal waters, estuaries and oceans.

Status: Common

Size: Bell up to 3.5 cm.

*************************************************

I don't think I will scoop any up into a bucket, just the same!

Cheers,

Bob.

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I have seen these many times in the harbour as far up as Gladesville bridge and heaps of them in Pittwater. As Bob saw, they really do seem to hunt there prey, pretty amazing with an animal that dosen't have eyes or a brain!

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There are bound to be experts out there and I'm definitely not one but I have family on Magnetic Island so I'm reasonably familiar with what to look out for.

These guys definitely aren't the real Box jelly... the Box has distinct groups of tentacles at each corner.

It's also not an irukandji... these guys are really tiny (only about an inch/2.5cm across) and since the photo was with a mobile phone I'm guessing it was substantially bigger than that.

Any marine biologists out there?

Cheers, Slinky

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Here are the box jellyfish :1yikes:

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Might be these little fellas.

Home Animals Cnidaria Jimble

Jimble Fact File

Carybdea rastoni

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Jimble, Carybdea rastoni

Photo: Dr Isobel Bennett

The Jimble belongs to the cubozoan order of jellyfish. All cubozoans have a box-shaped bell with tentacles at each corner. They are generally strong swimmers and have painful stings. Some tropical cubozoans are among the deadliest of all venomous marine animals, including the Box Jellyfish (Chironex fleckeri).

The Jimble, however, is not dangerous. It does sting but the venom potency is nowhere near as potent as its tropical relatives. It is the only cubozoan that occurs in the colder southern Australian waters. Occasionally it can be present in high densities in Sydney Harbour.

Distribution:

Western Australia to Southern Queensland.

Habitat:

Coastal waters, estuaries and oceans.

Status:

Common

Size:

Bell up to 3.5 cm.

Sting:

These jellyfish can deliver a painful sting. If stung, wash the area with vinegar and apply a cold pack to relieve the pain. Seek medical attention if necessary.

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