Is this a weird kind of hydra?

[Stella]

Some new critters have turned up in my critter tank. :happy2:

I thought they were like a furry algae with an umbrella shape, was trying to take some photos of on when the fish swam past and it FLINCHED!

They are up to 4mm across and hang from a very very thin thread, very hard to see with the naked eye, but just visible in the first photo. The 'tentacles' are very very soft and floaty.

This photo shows one just hanging there, and the second one showed it 'flinching'. They do this extremely fast - blink of an eye. They move like if you stretch your hand out and then suddenly make a fist - the 'tentacles' seem to suck into the centre.

Knocking the tank doesn't make them contract, but they do it at other times. I haven't seen anything obvious trigger them, just randomly contract and immediately release, but mostly stay open.

For reference: a hydra (eating a daphnia). Quite a different critter.

I have absolutely no idea what these things are, anyone got any ideas? :dunno:

[Caryl]

None whatsoevr but they look cool! :bounce:

[alanmin4304]

They look like a tube worm or a UFO.

[Stella]

actually I saw a thing on the 'news' last night about a UFO sighting, and was thinking that aliens are just as likely to look like these critters as anything else.

A better photo of the hydra: daphnia successfully ingested!

[Sophia]

if that green thing is hydra, what are the white ones I've got then?

Mine has a tiny dot in the middle of the star but yours doesn't appear to have that. Mine look like a tiny multi tentacled star fish on a stalk.

Do your hydra appear green to the naked eye just looking at the tank normally?

edit.....

both of ours seem to be hydra - green or white. Mine look exactly like the one second from the left on the top line

http://tinyurl.com/292s8br

on another site I found suggestion that the green ones have eaten algae

I will keep looking for your other thing

[Insect Direct]

thats a cool pic.

hydra are normally white. or atleast to my eyes