Identification please

[cnhgilbert]

I noticed these and was wondering if anyone would be so kind as to put a name to them.

[weez1959]

The first pic is hydroids

[FireEater]

Second pic looks to be a macro algae, possibly the beginnings of a Caulerpa variety.

[smpolyp]

1st pic I agree with weez1959. Second pic my guess would be gracilaria.

[Ninong]

Hi cnhgilbert,




Yes, the first pic does appear to by hydroids and the second pic does appear to be one of the many differenent species of Gracilaria, a beneficial macroalga that most tangs, rabbitfishes and other herbivores will gobble down on sight. I take it you don't have any of those in your tank at this time?

Biology of Gracilara

Erect thallus arise from a small discoid holdfast. The thalli are generally cylindrical, depressed or blade-shaped, with lateral, alternate or subdichotomous branches. Sometimes several different branches may be found in one plant. The external appearance of thalli may be used to identify species. The style of the apex and the base of branches are different with species.

I need you to look at the base, where it arises from the substrate (rock). Is it a small round shape or does it look like separate little "roots" (holdfasts)?

[cnhgilbert]

They were only growing on the glass. Additionally, they were not connected by and threads but, their bases are round. They have started clearing off the glass without reappearance elsewhere in the tank.

This is a very young tank and I have only 5 Clibanarius tricolor and 2 Lysmata wurdemanni. So I think they might be starving off.

[Ninong]

They were only growing on the glass. Additionally, they were not connected by any threads but, their bases are round.

The "round bases" are what are called "small discoid holdfasts." Algae are not true plants and they do not have roots. They have holdfasts. Sometimes the holdfasts look like roots and somethimes they don't.

So I think they might be starving off.

They are a photosynthetic alga. They use light for food, so they're not starving.



P.S. -- The hydroids are bad guys; the green Gracilaria is definitely a very good guy.