Is this a spider??

[caltman]

Can someone please tell me what this critter is? My best guess is that it is a sort of marine spider that came in inside one of my new polyp type corals. It sure looks evil and needing to be removed from the display, but I am super curious what it is and how it got here. It was noticed several days ago and it seems to be growing attached to the side glass for now. It is about 1/4 inch long at the moment and for now, content to just hang out.

 

[dvgyfresh]

Aptasia pest anemone

 

[MaxTremors]

Yep, it’s an Aiptasia, just carefully scrape it off the glass with a razor blade. Be careful that you don’t cut any part of the body, you want to remove every single part of it, anything left behind will grow into a new anemone, which will then be able to spread. They’re not the end of the world, as far as pests go, it’s virtually impossible to avoid them if you’re in the hobby long term, just read up on them and do your best to get rid of/manage them.

 

[NeonRabbit221B]

Don't try to remove it with a razor... just a bad idea.

Inject it with kalk with a hypo needle. If you see one you likely have more.

Also a better picture would help but fairly sure it is an aiptasia.

 

[NashobaTek]

Agreed with above

 

[MaxTremors]

Don't try to remove it with a razor... just a bad idea.

Inject it with kalk with a hypo needle. If you see one you likely have more.

Also a better picture would help but fairly sure it is an aiptasia.

If it’s on the glass, removing it with a razor is the best and most effective way of removing it. I agree that if it’s on a rock or some other non-flat surface, removing it with a razor blade would be a bad idea, but on glass you can easily get every single part of it without worrying about it releasing spores or leaving behind any tissue. They have a foot just like any other anemone, on glass they can be carefully detached with a razor blade.

 

[caltman]

Thank you everyone! I carefully scraped it from the glass with a razor blade with one finger holding it to the blade on its way up and out of the tank. Hopefully I got every last cell of this thing and that is the end of the issue for a while. I have recently added some corals that sort of resemble an aiptasia so I can see how it was missed at the LFS. With their large displays of corals, I would bet this is an ongoing issue for them now that I know how common this pest is.
Now I see the value of having a quarantine tank. Add one more thing to my experience tool kit as a new reefer. Someday, I might even get good at this.