strange stinging worms in my marine aquarium

Question
Hi Marcus,
I had a quick look and if the answer to this question is posted, i missed it. I need to know as its affecting my maintenance of the aquarium.
Lately, when i change water and clean sponge filters in the tank, I come up with an extremely itchy blistery rash on my hands. This started shortly after introducing a small sea cucumber. coincidence? Well, i started looking closely and I've noticed little caterpillary things in and around the filter, corals and even in the substrate. They look a bit like little centipedes. They are not slow moving. They are around a centimeter long. I cant find anything like them on the net up to now.  This morning while getting the filter sponge off, I touched one and it stung. only a little irritation, not a big sting. I know by tonight or in the morning my hands will be madly itching and I'll have blisters. What are they?  How can i get rid of them?  
The tank is a 90 liter aquarium with one snowflake moray and a small sea cucumber(I'm now regretting getting that as i think it may have introduced this thing)
I love my eel and I don't want to accidently kill him.
Please help .

Answer
donna,

i am very sorry for the delayed reply i must have missed the email, you have bristle worms, these worms are usually harmless but some people are allergic so they can have some pretty nasty stings if you are. they are harmless to your fish unless you have the larger variety, but those are very rare and i doubt they are in your tank. they are a very beneficial part of your clean up crew. i would just suggest trying not to touch them.

as for the snowflake in a 90 liter tank, i am unsure of the correct ratio of liters to gallons, but i know that tank is a bit small for a snowflake eel. once he gets larger i would suggest moving him into a 75 gallon tank or larger. but for now, he will be fine most likely, especially being the only thin in the tank.

dont worry the sea cucumber had nothing to do with the introduction of these things, they were most likely present on your live rock and your population may have just started to increase.

best of luck,

Marcus