Jellyfish!?!?!?!?!

[Zoaelite]

Originally Posted by justinl

well... technically any crustacean larvae are called nauplii tony

hydroids and cnidarians can have what is known as a medusa stage. the medusa looks like what most people know as a jelly; hydroid medusae are called hydromedusae and look very similar but have a few mostly anatomical differences. All of them have a polyp stage. medusae are supposed to settle and make a new polyp but I highly doubt that they can accomplish this in captivity unless special precautions are taken.

in the end though the result is the same; it will get eaten or chopped in a pump, either way it will die without causing any harm.

If I'm correct the phylum cnidaria also contains Anthozoa (The corals in our tanks) which do not have a medusa stage. As for the not causing harm thing, im sure 95% of the cnidarian species in our tanks are harmless but I have seen Jellyfish completley wipe out a sea horse tank.
Levi

[Myka]

About 10 or 12 years ago when I had my first reef tank I had a large amount of little "jellyfish". I seemed to think they came from little creatures that looked like mini feather dusters, but that was so long ago that my memory only serves me the way that I recognised it then. If I knew what I know now, I think I would have been able to identify the mini feather duster things, and probably come to the conclusion that the "jellyfish weren't coming from them. Who knows! But the "jellyfish" I had only came out after lights off, and they filled the tank probably 1 "jellyfish" per 2-3 cubic inches of water. I remember very clearly that there were a lot of them. I didn't have much for pumps to kill them though, as back in those days all I had was an undergravel filter, and an AquaClear HOB filter.