ID help, white things on glass

[Talonstorm]

I need some help identifying the white things on my glass. I have a bunch of pods, but I also have:

This thing, which is the size of a sugar crystal (tiny). It moves its little "legs", but the center body doesn't move to the best of my knowledge. There are hundreds of them on my glass.

Another picture of it:

Then there is one of these, it looks like a blob of jelly with stuff in it and 2 long "tenticles" with little whisps coming off them. It stretches out the tenticles and sucks them back in. There is a pod in one of the pictures for size comparison. Pictures:

and in this picture I drew arrows pointing at the whisps.

Any ideas & good or bad? I looked around at the popular hitchhiker ID websites, but the closest thing I found was something similar looking to the first thing, it was a jellyfish of some kind? Is that right? It is kind of fun finally finding life in my tank, hope these are good guys!

Thanks,
Tina

PS - My brown algae is turning green now, this is just since I started doing water changes using RO/DI water (with salt of course). Why??

 

[Anonymous]

1st one is a hydroid Jellyfish.

2nd kinda looks like a ctenophore aka Comb Jellyfish. Interesting to find one on the glass.

 

[Talonstorm]

Thanks for the reply! Should I leave them alone, or are they bad guys?

Tina

 

[Anonymous]

If it were me I'd destroy the Hydroid. They can multiply to plague proportions.

The Ctenophore is a pretty cool so I'd tend to keep it just to study it. I don't know if they can reproduce in a captive environment. I wouldn't think so but I'm not sure.

 

[Talonstorm]

Is there anything to eat the hydroids? There are hundreds already on the glass alone. There is only 1 ctenophore that I see.

Thanks,
Tina

 

[Anonymous]

I've seen Keyhole Limpets wipe out Hydroid colonies but I'm told by the experts that Limpets don't eat hydroids. I suppose the jury is out on that one. I don't know of anything else. I believe they stop reproducing when they are scraped off the glass. The buds that have already left the stem will settle again though.

You could try using some type of micron filter to remove their food until the population decreases. Other than that I don't know. Hopefully someone else will have viable suggestions.

 

[Anonymous]

What Guy said.

 

[Talonstorm]

I scraped off as many of the hydroid jellies as I could (some I just can't get to on the tank back and by the rock). I also scraped the comb jellies off. The one tripled in size in a few days time and I found 4-5 more of them in various locations on the glass, also growing at a rapid rate.

Tina

 

[mejiggery]

I always had a few hydroid jellyfish popping up in one of my tanks, they never got to o many of them though but i found they just disappeared as quickly as they came.
never experienced the combs in my tank though.

 

[Talonstorm]

I scraped these guys a few times and they kept coming back in force within a couple of hours. Finally, I left them alone and they went away on their own. I thought for a while I would never get rid of them!

Tina