[Closed] Jellyfish suicide.

I once saw a small fat German boy (think of Augustus Gloop from Willy Wonka) eating a washed up dead jellyfish on a beach in Greece. No wonder he was so fat 🙂

Rhizostoma pulmo, otherwise known as the 'barrel' or 'dustbinlid' jellyfish.
They can get a good bit bigger, too!
It is always sad to see them caught out on the sand, poor buggers. They don't really have any way of avoiding it. If they are too big to move, dig a pit around and under them so that it fills with water and they don't dry out. They will get washed back out at high tide.

It really shouldn't come as a surprise to me by now that STW has a jellyfish expert.

They were a great band

cdoc - Member

Rhizostoma pulmo, otherwise known as the 'barrel' or 'dustbinlid' jellyfish.
They can get a good bit bigger, too!
It is always sad to see them caught out on the sand, poor buggers. They don't really have any way of avoiding it. If they are too big to move, dig a pit around and under them so that it fills with water and they don't dry out. They will get washed back out at high tide.

A bit more info would be great. Don't really know anything about jellyfish....

How do they breathe, for example? I take it they have some kind of gills?
They don't have a brain, do they?
Are they around the whole UK coast or only warmer areas?

TTTT!

(Tell The Turtle Trackers)
http://www.mcsuk.org/what_we_do/Wildlife protection/Report wildlife sightings/MCS Jellyfish Survey

Last 3 years there has been a huge increase in numbers off our coasts.

Blame fertilisers washing down into the sea & GW (of course)

My sister trod on one well over a metre in diameter 30 odd years ago in Cardigan Bay, Wales. Had to stick her in a hot bath, apparently the poison denatures if the temperature rises too high above that found in the sea.

Cool story bro etc...!

That's really cool, seen a lot of your standard moon jellyfishes... jellfi? But never seen one of those.

samunkim - Member

Blame fertilisers washing down into the sea & GW (of course)

It's not nice to talk smack about people when they're banned and can't respond.

Used to sail around Anglesey, there would be hundreds/thousands/millions (more?) in the water around the Menai Straits, mostly they were the usual <5" or so (moon jellyfish?), occasional there'd be a shoal (school, flock?) of bigger ~12" ones, then every so often there'd be a huge one like that, in the water they're massive, as big as a person.

Used to be told it was due to overfishing so the young weren't getting eaten and once they're a certain size they have no natural predators,

[img] [/img]

[i] If they are too big to move, dig a pit around and under them so that it fills with water and they don't dry out. They will get washed back out at high tide[/i]

So they're not dead? Excellent 🙂

A good way to think of them is as free-living corals or anemones as they are all slight variations on the same bodyplan.
They don't breathe as such, having no respiration system as they do not require it. They work by cellular respitory diffusion, in that they have very thin cell walls which allow O2 to cross the cellular membrane.
No brain or central nervous system is required either as they react to external stimuli much in the same way as plants do. They sense their surroundings, touch and temperature via a system of nerves which then deliver info to a segmented ring of nerves around the rim of the jelly, with each segment controlling a section of the mantle and its associated feeding apparatus. By stimulating some areas of the mantle they have some control over their direction and depth, but again, this is due to environmental feedback, not actual choice.
Weirdly though, they must individually put in so much effort to maintain the congregations that they form.

Also, all over the UK. Barrels feed on planktonic organisms with a slight preference for those in warmer waters, so they are rare in the far north. But then, currents drag them all over.
This is a good one, Eil Malk in Palau.
[img] [/img]
It used to be connected to the sea via underwater passageways which have since closed up.
[img] [/img]
The little guys that were trapped diverged into something closer to a photosynthetic organism due to a lack of plankton (most cnidarians utilise symbiotic photosynthetic bacteria to supplement their feeding).
Over the course of the day they follow the sun across the surface of the lake, gathering in the lit spots in huge concentrations!
For an animal that only reacts to environmental inputs, they are capable of surprising behaviour.

Also, don't follow the above advise about digging around them if they are little and blue...
Portuguese Men'o'war hurt quite a bit and their feeding tendrils can be really hard to see against the sand!

I am. In awe.

Nice one [b]cdoc[/b]!

Am I correct in thinking that they can still 'sting' even when washed up and 'dead'?

Wow! Nice explanation, cheers.

I seem to remember seeing a program about them years ago, but can't remember much. I seem to remember something about them having some control over movement, but not much (as you explain above).

I take it they don't have 'mouths' then, to feed?
I've seen footage where they 'catch' quite large fish which then get pulled up into the 'body'.....how is the fish then eaten?!

I've seen different footage of turtles eating jellyfish (which sadly relates to the whole thing about turtles ingesting plastic bags...). Does this mean that turtles are immune to jellyfish venom, or does their tough skin mean that the venomous barbs can't penetrate.....?

The natural world is pretty amazing.....

do like we did as kids, cover them in sand and slice em up with your beach spade. Filthy things, make swimming in the sea highly frustrating.

jellyfishes... jellfi?

It's not nice to talk smack

The food is drawn up into the mouth/anus opening and into the 'gastrdermis' where its presence causes the release of enzymes to break it down as its nutrients are drawn across the cell walls to feed the jelly.
Nice.

As for the envenomation of turtles, it just can't happen. Jellies sting with little coils of cells that culminate in a barbed point called nematocysts. These fire when stimulated and push small amounts of very potent toxins into the target, however turtles are far too tough to be penetrated by the sting and the tiny amounts of toxin are not poisonous when consumed.
Turtles tent to go for larger species that do sting, but often eat only the body. It has been proposed that they simply do not like the taste of the feeding apparatus.

As for size, here, have a Deepstaria enigmatica. We know bugger all about this one.

jekkyl - Member

do like we did as kids, cover them in sand and slice em up with your beach spade. Filthy things, make swimming in the sea highly frustrating.

Edit, yes, ones that do sting can still be potent days after death.
Moons, compass and barrel jellies are the most common over here and they are pretty harmless.
But then, some people don't check first....
I remember a story of a Lions Mane jelly drifting close to the beach where it was surrounded by beachgoers having a look! I think nearly 100 people were stung by a single animal that day.
Found it. http://newsfeed.time.com/2010/07/22/nature-attacks-giant-dead-jellyfish-stings-150-beachgoers/

johndoh - Member

Was this deliberate? The collective noun for jellyfish is a 'Smack'

God DAMN I'm witty.

No it wasn't deliberate

Don't see any in the Solent, but then it's probably far too toxic.
You do occasionally see them on the South side of the IoW, Freshwater Bay seems to be popular.

Am I correct in thinking that they can still 'sting' even when washed up and 'dead'?

Google tells me that these barrel jellyfish are harmless as their sting cannot penetrate human skin. Same with moon jellyfish, though look out for the Portuguese fellas as cdoc says 😉

Still don't think I'd be picking one up...

I am correct that they're technically sort of immortal - they can be killed of course, but left to their own devices rather than die of old age they revert to an infant form and mature again over and over?

It's just like the New Zealand Pilot Wale Massacre* all over again. 🙁

*Fake News

Once, when kyaking off Cornwall I saw something like that in the water. It looked a foot or so across and a few cm down...so I tried to prod it a little with the oar.

When the paddle was all in the water I was able to guess the true size. It was a meter or more across, and a lot deeper down than I thought! I tried not to fall in after that.

Yes P-Jay, that seems to be the case, however it is very difficult to note if senescent decline still occurs after (x) amount of reversions.

If you are after a truly immortal animal, look no further than the Arctic Quahog clam, Arctica islandica.
You can find their shells on most UK beaches, but if left to their own devices (without predation, disease or severe environmental change) will keep on going forever with no loss in reproductive ability.
[img] [/img]
This one was dredged up in the prime of its life at a a mere 507 years old.

Have seen plenty of those big ugly ones around the beaches of The Solent. Will dig out a photo later

big ugly ones

They probably think the same of us.

Jellyfish suicide.

Only jelly shots at the bar though :/

Probably 10 or more that we found. We were unsure of whether they were alive or dead. A couple were definitely dead as they'd be drilled against the rocks. Great bit of info. Thanks cdoc.

I was kayaking in the sea in Devon as a kid, stuck me paddle in one side and somehow scooped up a jellyfish which then flew over my head and landed in the water on the other side.

True story 8)