Hitchhikers on live rock identification

[mepar]

Hi everyone,


New here. Can you help me ID some hitchhikers on my live rock?


Thanks everyone!

 

[KING KONG]

Hi everyone,


New here. Can you help me ID some hitchhikers on my live rock?


Thanks everyone!

Very difficult to tell but looks like sponge from 1st pic. Do you have any flower like structure in 2nd photo? Like here it looks like you have hydroids as well still not very clear about this. Still if u have flower like structure Google search colonial hydroids

 

[ISpeakForTheSeas]

The second pic is full of sponges, the first pic is pretty blurry but it may be a sponge as well. Harmless filter feeders.

 

[KING KONG]

The second pic is full of sponges, the first pic is pretty blurry but it may be a sponge as well. Harmless filter feeders.

Is it hydroid? Unable to watch this clearly in my phone but it seems like hydroids

 

[ISpeakForTheSeas]

Is it hydroid? Unable to watch this clearly in my phone but it seems like hydroids

It is somewhat difficult to see, but I'd guess that's just the new growth of the sponge.

 

[vetteguy53081]

Hi everyone,


New here. Can you help me ID some hitchhikers on my live rock?


Thanks everyone!

poriferan type sponge known as Syconoid sponge and are harmless

 

[mepar]

Thanks everyone! I found a few more that need ID.

 

[ISpeakForTheSeas]

Thanks everyone! I found a few more that need ID.

The first one is an Aquilonastra starfish (known in the hobby as Asterina - see the super long response below). The second one seems to be a feather duster worm - harmless filter feeder.

Also, since I neglected to the first time, welcome to Reef2Reef!

Now the long response:
I've heard some species of Aquilonastra eat corals and others don't - I've seen convincing evidence for one species (a very darkly colored one), and one piece of somewhat convincing evidence for one different species, but the vast majority of these guys seem to be at least mostly safe.

With regards to whether or not the average "Asterina" (technically Aquilonastra - Asterina is a separate genus within the Asterinidae family) eat corals, it might be a species specific thing, it might be a you have way too many starfish so they're out of other food options thing, it might be they're eating the slime coat/mucus on the coral rather than the coral itself (see below), or they might just opportunistically eat unhealthy corals. Based on how starfish eat, it seems plausible to me that it may also be coincidental (i.e. the star goes to eat something off the coral and the coral just happens to be one that is able to be negatively effected by the star's everted stomach). Regardless, Zoas are just about the only coral I've heard about regular "Asterina" stars potentially going after (so them potentially going after a birdsnest coral is news to me).

A quote I like to refer to for this:

Timfish said:
It's an Aquilonastra spp. starfish and is a great scavenger. I see them with anywhere from 4 to 12 legs. The whole discusion around them seems to me excellent examples of misidentification, mistaken behaviour and assumed causality based just on heresay without looking at the research. Asterina spp starfish are preditary but only reproduce sexually and are shortlived so while it's possible some might get into a tank even if it did happen it's not going to be around long. Aquilonastra are one of the uncommon species that reproduce fissiparous or by splitting so are easy to identify by the different sized legs regrown after splitting. They perform an important function not only feeding off algae films but also feeding off microbial films including those on corals (at least ones that don't sting). FYI the mucus coating on corals ages and corals have to periodicely shed it to renew it and maintian healthy microbial processes (Ref 1, Ref 2). If Aquilonastra are feeding on zoas or softies I'll argue they are either benign or even beneficial as they may be reducing the unhealthy older mucus which can be full of unhealthy microbes which the animal is trying to get rid of and are far more likely to be the actual problem.

Here's an example, this Toadstool is doing one of it's periodic sheddings. The Aquilonastra have been in this system for years but only climb onto the Toadstool when it's shedding. In the first picture you can see the old mucus film, Aquilonastra starfish and areas they have cleaned off. The second picture shows the Toadstool a week later.