Jelly fish hitch-hiker

[ScottyS]

I turned on the lights this morning and found the tiniest thing "swimming" in my tank. It looks and "swims" like a jelly fish. I pulled it out with a turkey baster and have it in a jar for now (no way it'd survive the powerheads and overflow trip to the sump and back thru the pump if I left it in the tank).

Any ideas on how I can try to keep it alive?

 

[ScottyS]

Baby jellyfish

Baby jellyfish

I've since learned (actually saw it at an aquarium years ago) that jellyfish as free-swimming planula larvae attach to something and develop into polyps. These grow and eventually become segmented (strobilation) and then each segment breaks off as a new baby.

I must have had that happening in my tank, because I found many more and managed to collect 8. I have them in a small plastic container in the tank with a mesh from a filter bag over the top. I put a tube from a small powerhead outlet into it for circulation, and have hatched baby brine shrimp fo food. It would be amazing if any can be reared to larger sizes.

 

["Umm fish?"]

In our tanks, those are almost always the free-living life stage of hydroids. Some people say that their polyp stage will kill corals, but I've never really had them turn into a problem in my reef tanks. They survive really well if they can get enough to eat, but the polyp form is really small and not much to look at.

They are horrible if you ever try to raise fish larvae, though. They will often increase to plague proportions in larvae-raising tanks and eat all of the fish larvae.

Good luck!

 

[ScottyS]

Hydroids uh? Never thought of that. Their bells are about 3mm and pulse. There are no tenticles hanging from the bell but a flare shape thing hanging down from the center. I'm feeding them baby brine shrimp so I'll see if any survive and grow.

 

[oceanparadise1]

can u get a pic by any chance?

 

["Umm fish?"]

This would be the place to take a look:

http://www.wetwebmedia.com/jellyidfaqs.htm

 

[ScottyS]

This is the 1st time I've tried to post a picture, so I hope it works...

This is one up against the glass looking down at the top side of the bell. You can see the body/mouth thru the bell's tissue.

I've now found some still attached to the rock, pulsing like it's trying to break off. Interestingly they appear to be mostly (but not all) growing off rocks that were not "live" 5 months ago. When I set up the tank I needed some flat rocks to fill some background space and I had live rock from a past tank that were in buckets with a pump for months. I had had a lot of bristle worms so I sterilized the rock by baking in oven at 500 degrees for an hour. So these pieces have now "cycled" in the tank, so growing hydoids makes sense.

 

[VacavilleFC3S]

yup hydroid

 

[ScottyS]

So that means they will not grow much bigger? No point keeping them in a little breeder tank hanging in my tank, feeding them trying to get them to grow.

 

["Umm fish?"]

Well, it's not so much that you can't keep them. Their polyp stage is really small. Here's some from my old tank. If it gives you any idea, that huge black thing that they're on is a zip-tie.

 

["Umm fish?"]

Oh, you meant the medusa stage, too? I've never seen one that got terribly big. Sorry....

 

[ScottyS]

If they were jellies, I'd like to see if I could keep them alive. But hydriods would just be food for the filter feeders. We have people coming over for the 4th (barbebue in the rain) who have seen the work in progress over the past two years (removing a small tank, replacing it with a reef-ready wider one, plumbed through the wall behind it to a sump and skimmer in the basement. That plus moving an air vent took 2 years). Some of our guests have not seen this (or any reef tank) set up, and the small breeder tank within is an eye-sore.

 

[physalia]

It may be an upside down jellfish (Cassiopea sp.). It is common for their polyps to be found on live rock. If so, they will need light in addition to food. Can you get a pic of the polyps that are generating the medusae?

 

[ScottyS]

<a href=showthread.php?s=&postid=12941573#post12941573 target=_blank>Originally posted</a> by physalia
It may be an upside down jellfish (Cassiopea sp.). It is common for their polyps to be found on live rock. If so, they will need light in addition to food. Can you get a pic of the polyps that are generating the medusae?

No, because there are none close enough to the glass for me to get a close-up. I think they first look like little long stalks with a ring of long tenticles. the ring grows into a bell and the tenticles shrink. The bell starts pulsating and in a few days breaks off.

I've given up and let lose the ones I had in the breeder tank, but still see some free swimming ones from time to time. If it may be Cassiopea I'd love to catch them again and try to rear them; I had the breeder tank near the MH light and feed them live phytoplankton.