Unidentified living creatures in the gravel

[MacBeth]

My saltwater tank has been established for about 6 months, and a couple of months ago I started noticing these tiny little creatures in the gravel. They were less than a centimeter each and we could see them crawling between the layers of gravel. There didn't seem to be too many, so I didn't worry too much. But as I was cleaning it this afternoon, I found that they had doubled in size and got much darker, and in syphening only 5 gallons of water from the tank floor, I managed to kill A LOT of them. They look like tiny centipedes. Does anyone have any idea what these are? If they are problematic or dangerous? Or if they are a good thing. Currently they are freaking me out. There have to be thousands of them. Thanks in advance for your help.

MacBeth

 

[nightrydaz04]

Do you have any live rock or coral?
If so I imagine they're probably an invertibrate of somesort.
Could you post a pic?

 

[wayne]

They sound like small bristleworms. Not dangerous, good scavengers

 

[S.Reef]

Bristleworms or fire worms.

 

[1979camaro]

i concur...though there is minimal danger if they become too abundant...i have seen them boring into the skeletons of LPS corals and I would assume they do the same on SPS...watch your hands too, they are called "fire worms" for a reason

 

[S.Reef]

Oh yeah...they will also burrow into clams and kill them from the inside out. If or when they get out of control, dottybacks, some wrasses, and arrow crabs will consume these.

 

[dbacksrat]

has anyone here ever actually been stung by a fireworm? how much pain are we talking about? just want to know because i have a tendency to get bitten, pinched, or stung by nasty animals in strange places

 

[1979camaro]

lol....thick rubber gloves bud

i personally have not brushed up against one but I have seen pictures of some pretty nasty hands....lots of swelling etc...medical attention is sometimes necessary...really though, if you are careful you should be fine (knock on wood)

 

[nightrydaz04]

AHH... THE DANGERS OF SALTWATER FISH

 

[wayne]

The real nasties nowadays come out of the Caribbean so I'd be a bit more careful if i had something like Tampa Bay rock. But for most others, they don't live up to their reputation

 

[MacBeth]

...Amphipods...

I started doing some research about bristleworms and looked at several pictures, and though they sound an awful lot like them, they more closely resemble amphipod's (a crustacean), which makes me feel a bit better. Also, I spoke with the guy who owns the marine store I've been going to for years and when I described them to him, he agreed with what I was looking at. The bristlewomrs looked more like actually worms, these are almost as wide as they are long and their (legs) appear very hairy. Like fat little centipedes, or even itty bitty shrimp. They are just strange. He recommended that I use a wrasse or a goby to keep them in check, but he said they are not problematic. Any additional thoughts?

 

[1979camaro]

sounds reasonable to me

 

[S.Reef]

They can be if left unmaintained.

 

[S.Reef]

Become a problem that is.

 

[phantomfe3]

too many pods? youve got to be kidding me. alot of people with saltwater would BEG for an abundance of pods! with alot of pods you can get some pretty awesome fish like a Mandarin or a Scooter Blenny, awesome fish

 

[Hwarang]

Yes, it sounds like you are describing copepods or amphiods, of which there are many many species. They are quite harmless, in fact they are considered a part of your natural filtration, or perhaps the cleanup crew. An overabundance of them in your system could indicate excess detritus or suspended particulate matter in the water column. Mature tanks almost always thrive with these creatures. In my largest SW reef, I had counted 10 different species. Some crawled like miniature silverfish with huge jaws. Some looked like little flying lobsters (google: mysid shrimp), some were the "tunnel runners" you describe, and I even had a swarm of "fleas" hehe. I really dug these little guys.

Is this what you see in your aquarium?

http://www.reefs.org/hhfaq/pages/picture_pages/faq_amphipod.html

Good luck!
-me

 

[MacBeth]

That is them. Thanks for finding such an awesome picture. It is good to know that these little guys are a benefit. Do tomato clowns eat them?

 

[Hwarang]

Not that I'm aware of. Clowns like meaty food chunks. Amphipods and copepods are typically consumed by fish that flit and hover over the reef, have small downturned pointy mouthes and are not large. Mandarin dragonets, for example. Some gobies and some wrasses I think too.