Duncan and Emerald Crab Symbiosis?

[gizmodo]

Hello all,

Like many of you, I was having trouble with my imverts attacking corals. Specifically, my Duncan was getting constantly harassed by every invert in my DT.

I'm going to provide lots of detail because I want to give as much info as I can on a behavior I've never seen before. Skip to the last two paragraphs if you want to get to the important info.

I started feeding more heavily, with LRS nano Reef frenzy, nori for crabs and my pincushion, fauna Marin Coral pellets, hakari mysis, AB+, poly booster, Reef Roids, phytoplankton, Vitalis mixed reef powder and now live brine Shrimp on a dosing pump.

I was hoping by providing a diverse diet for everyone that aggression would decrease and corals would have all the food they needed to recover from injuries caused by inverts.

For the most part my emerald crabs stopped attacking corals and coral health and coloration seemed to be improving. Then, I notice my cleaner Shrimp was harassing my Duncan every day. Feeding the shrimp directly before everyone else did not help to quell the attacks. So I ended up removing the shrimp and I isolating it in a new system.

Then, a few days ago I noticed something very interesting, one of my Emerald Crabs is being hosted by my Duncan. The crab is no longer attacking, but is seeking refuge in the coral. It will venture out for a while but it always returns to the Duncan. Furthermore, I've observed it cleaning the coral and even what seems to be defending it from my hermit crabs. It's not taking the food I give to the Duncan either.

Has anyone else seen this kind of potential symbiotic behavior? I haven't managed to get any good videos yet but I'll post them here as soon as I get some usable footage and pictures. I'd love to hear what you guys think. The video attached does not show the crab latching onto the coral like it normally does. But often enough it acts like a porcelain crab inside of an sps. I just can't get good camera angles on it yet.

 

[AlyciaMarie]

Interesting! I haven't heard of it, but it's not surprising either. There are some pretty odd/interesting pairs in the reefing world. Is the Duncan tolerating all the activity from the Emerald Crab? Sadly, I can't see the picture. I'd love to see a video if you have one!

 

[formallydehyde]

For a while my emerald crab formed an ideal little hide underneath an overhang of a stylocoeniella frag. As it grew it actually formed around his body so he fit completely snug when returning to the stylo. When I got him, he also hung out almost exclusively underneath my pocillopora for a while, even though there were better canopies to hide under. I wouldn't be surprised if emerald crabs (or at least some of them) feel safer by corals.

 

[moretor1]

Not that surprising as if I am correct corals can't sting through most invert exoskeletons so the coral isn't any danger to it and it offers better protection against fish than a rock would

 

[PharmrJohn]

I'm not surprised either. Corals have been a safe haven for all sorts of marine life in the wild. Pretty cool!

 

[moretor1]

Funnily enough my new emerald crab has been hanging out on the base of my duncan for a while too

Duncan doesn't mind either

 

[NanoNana]

I don’t have an emerald crab but I have a Pom Pom crab that lives in a Duncan colony and a yellow clown goby that thinks it’s clown fish and hosts another Duncan colony. It doesn’t just sit on top of it like clown gobies do. As the tank nears dark it gets down in between the heads and wiggles like a clown fish. Stays inside the colony until the “sun” comes up then perches on my bernardpora all day. Doesn’t bother the Duncan a bit to have a roomie. The Pom Pom definitely defends his Duncan home.