worms and crabs and snails on my corals: problem or not?

[Sk8r]

Generally not, but they may occasionally point up a problem which they are in process of solving.

I've seen a lot of new owners quite upset because, say, a scarlet hermit walked across a coral. Or is sitting on it. No problem. These inverts aren't heavy, and their tiny feet really don't even disturb the surface. A crab isn't going to bother a leather coral, eg, or even a montipora.

Same with some of the smallest snails: dove snails, colonistas, strombus grazers, etc: they actually help a coral that is getting an algae overgrowth. Pyramid snails, which are smaller than that, ARE to fear, with clams: they're bad news. But your average snail won't bother a coral, and the very small snails look to be doing something scary, but they're actually removing a troublesome algae and maybe some coral slime. It lets light get to the coral skin, which is a good thing.

Worms on a coral are not a problem---but they indicate a serious problem. Bristleworms can only slurp slime: they have a soda straw for a mouth, no jaws at all. But if they're massing around a coral and removing something, they're trimming off dead tissue. They didn't cause it---they're actually the coral's only hope of shedding it, the way a doctor will clean a wound. But it points up a problem that may need you to 'frag' the coral or take some measure to save it.

Ironically, since crabs, snails and worms show up to clean up a dead critter or dying area---novice reefers often assume they CAUSED the death or damage. Think of them as the doctors and undertakers, not as the culprit or cause.

Some researchers even think that bristleworms help feed certain corals, because bristleworms suck up refuse and produce a poo that is of a size corresponding to coral 'mouths'. For what it's worth.

Shrimp. Ah, shrimp. Everybody's pain in the---whatever. Pep shrimp WILL experimentally snatch a single coral flower off your montipora or birdsnest...and generally they find out it's nasty and will not go on bothering it. What does bother the coral is when the owner goes in to try to catch the offending shrimp. Give it a bit: if the shrimp does it more than twice, THEN you may have a problem. If you need to catch a pep shrimp, try holding a slice of raw shrimp in your hand or in a net: he may come right to you.

Fighting conch---death on plate and other sand-sitting corals. It has a sharp foot it uses to push itself with, and this can slice the skin of one of these corals and kill it. Having a fighting conch and sand-based corals it can accidentally run over is just a matter of time...

Generally, tell yourself that identical critters have been living together for many, many thousands of years, and that the critters that make their living off poo, that we specifically select to put in tanks full of coral, tend not to kill off their environment. That's why you call them cleaners. Give them the benefit of the doubt until you see damage or until the coral reacts negatively: intervening in a tank is how corals get bumped by human hands and damaged. Observe---ask, if you're really suspicious---but don't generally assume the worst.

[Jscwerve]

Your Tuxedo Urchins, however, will attempt to help you redecorate your tank:

[Sk8r]

That's for very sure. The only thing I can say is---they are one of nature's little redistributors, and a safe way for a coral to travel.

[SeaCucumberFan]

+1. I've even had my banded coral shrimp walk on my...





Fish

[anthonys51]

i cant keep my cleaner shrimps away from my hand when i put it in the tank.

[Sk8r]

Most shrimp are easy to catch...but if all else fails, tilt a wine carafe up against the rockwork: the glass is slick and the narrow neck means it's even harder to get out. Works for crabs, particularly.