spider-like creature in live rock

[mryoung7]

i just noticed a small creature that has been hiding in a crevice of my live rock. i haven't added any live rock in months so it's obviously been in there a while. i'm 98% sure it's a spider of some sort. it's fuzzy and beige to light yellow in color. it either rarely comes out or only comes out when it's completely dark or i would have seen it long before now. it came out for just a few seconds to poke at the anemone when i spotted it.
as you can see from the picture below, you can barely see it's legs because it hides deep in the hole just next to the anemone.
can anyone tell me what this is and if it's a possible threat? i have had a couple of fish die on me in the past 6 months with no obvious reason but i am skeptical that this had anything to do with those.

 

[kreckner]

Have you been able to see the critter completely out of its hole? "spider-like in appearance" tells me that it could be a crab or a shrimp of some sort. Hopefully not a Mantis Shrimp. If it is, that could very well explain the loss of your fish. Any way you could get a closer picture? I know those small critters are rather difficult to get a good picture of.
Welcome to the boards.

 

[mryoung7]

thanks for the welcome.
now that you mentioned it, i guess that is what a crab would look like without a shell. i'm poking around him and he's curious but i haven't been able to get a better pic yet. i'll keep trying and post when i have one.

 

[mryoung7]

i feel pretty ignorant. it is definitely a crab - i saw it's tiny claws. it just will not come out of its live rock home tonight. now that you know it's a crab, can anyone identify what it is and if it's a threat? furry beige crab, about a half inch in diameter including legs.

 

[cain420]

there are way too many crabs to ID them even with a pic most of the time.. i never have got an ID for the one I found, but I gave the rock a sponge bath after seeing him pick at the coraline.. there are way too many species of crabs though..

 

[tscuda]

Well since theres a 1000 different kinds of crabs its hard to tell without a pic. I have 2 that sounds like yours but have black tips on the claws. I put them in my sump. They seem to be harmless algea eaters. Put a piece of meaty food near it and see if it eats it.

 

[mryoung7]

thanks for the help. now that i know it's a crab, i'm not worried. i'll just isolate it.

 

[coachklm]

sally lightfoot crabs are very spider in appearence

 

[777]

I had a mysterious spider looking crab appear out of no where. It turned out to be a decorator. Here is my pic.
https://www.saltwaterfish.com/vb/showthread.php?t=201477