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Freshwater Jellyfish


Man Yu

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  • 4 weeks later...
  • 8 months later...
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Well... I got my wish guys. I have a tank now overrun with freshwater jellyfish and I didn't even have to put them in! (well... not intentionally, that is)

Goodness, I can't believe they're so tiny! (about the same size as the space enclosed in an "o" in this font). It gives me headaches to focus my eyes on them, add to that the fact that they're semi-transparent... Very neat to observe though, they swim exactly like "Squishy", that tiny jellyfish Dory tried to adopt in Finding Nemo.

Also, sorry I couldn't post a pic guys. It'll take a very good-quality digital SLR to capture their image, and I'm not going to be able to afford that for a very long time... (I can't even own a standard digicam at present. argh...)

I'm guessing they came in with the plants I'm attempting to grow in my vacant tank. It's got no filters of any sort in it BTW, which is probably why they proliferated so fast (seeing how small and delicate they are, even an airstone would disturb them too much). Infusoria and lots of microorganisms also thrived in there, which provides them with food. I'm now in a quandary what to do with that tank now... I can't even perform a water change without potentially killing the interesting inhabitants! :wall

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^Now that I look at them again, they actually look smaller! :D It's their ring of extended tiny tentacles that's giving them a wider diameter!

I don't think they're full-grown already though... the pictures on Oliver Knott's gallery looks as if it might reach a diameter of slightly under a centimeter at least

well, I think the jellyfish have been there for a long time actually.... They only became apparent when all filtration and water movement had been turned off on that tank (as I said, even a very mild current would have thrashed them helplessly).

When I had first introduced java fern in that tank almost seven months ago, there suddenly appeared a curious mat of polyp-like things on the glass sides and the prefilter sponge of the powerhead. I couldn't determine what they are but let them be, as they didn't look like hydra, despite having minute tentacles (they resemble barnacles more) They reproduced rapidly, probably due to the high turnover and plentitude of detritus from fish poo. At one point, they even covered the inside of the prefilter casing!

I recalled seeing a drawn diagram of the life cycle of marine jellyfishes on a biology book and that they go through a stage of sedentary substrate-attachment during which they look like coral polyps before finally maturing as free-swimming medusae (larvae). I guess that's where the jellies started from and the lack of current when I turned the filtration off forced them to mature into free-swimming jellyfish (because they can't feed by filtering particles from the water anymore)

Edited by Man Yu
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