Hitchhikers, good or bad? Need help to ID.

[dochou]

Hi fellow club members. I just came home from the Silicon Valley CFM. I bought some acropora mini colonies. I found some interesting critters Each colony had 1or 2 crabs living in the colonies.
There was a green translucent shrimp or crab and some kind of feather duster like barnacle.
Lastey there was some sort of algea on the frag plug.

 

[dochou]

Barnacle thing. This one looks dead but there are others with feather-like fans coming out of them. See the video.

 

[dochou]

The red algae.

 

[dochou]

One of the 6 crabs.

 

[dochou]

Most of the crabs are black and white but 3 are darker, like this one.

 

[dochou]

Here is the videos of the green thing that looks like a shrimp. Initially I thought it was a piece of green ulva algae floating in the water. it was moving/ swimming very fast in the water.
In the video, initially you'll see the crab but later you'll see the green thing. What is the name of this thing? Looks a little bit like a tiny praying mantis bug. It's about 5mm.

 

[grizfyrfyter]

The crabs might be acro crabs. They don't have a ton of benefit to the corals but they also don't hurt anything. They get very stressed away from a colony though. Best to leave them alone.

 

[CaseyP]

The white with black eye band ones are good acro crabs. Not sure about the darker ones. Generally the dark hairy ones are gorilla crabs and are bad.

 

[Darkxerox]

Agree with Casey that all the little bandit looking acro crabs are good or at worse commensal. Zero idea what the little green crustacean is since it's hard to see in the video. The barnacles are fine too. The algae I've had before and it's not fun, so you could break the bases off the colonies and re-glue to where you want them to minimize carryover.

 

[dochou]

Okay. I just read an article on Acro Crabs and it looks like I have Tetralia spp. crabs. Common name is Bandit crab. They are beneficial to acro colonies. I don't have to do anything to them. Even the purple/orange guys are safe.

Acropora Crabs Commensal Guard Crabs

Keeping Acropora corals and other SPS alive in captivity can be a challenge, But you can enlist the help of tiny Commensal Acropora crab...

aquariumadventures.blogspot.com

I'm still doing research on the green shrimp.

 

[rdriggett]

Acro crabs are so cool and hard to get. Nice find!