Weird Looking Creature

[rondaw3]

I just purchased some new live rock for a new tank set up and I discovered a strange looking thing in the tank. It looks like a spider, is about 1/4 inch from top to bottom, round, sort of a light tan color with about 8 tenacles all the way around. It sometimes will "swim" around moving like a jelly fish and also will just float in the current of the water until it lands on something. Any help would be much appreciated.

Ron

 

[ophiuroid]

HMMM...need a bit more info, and a pic would be a big help. Is it squishy like, a la a jellyfish or anemone, or hard and jointed like an arthropod (crab, shrimp). I ask because there are such things as sea spiders, so I am trying to narrow things down to a phylum

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Brittlestars!! http://home.att.net/~ophiuroid
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[some'n'smellsfishy]

at first thought, figured it was an arrow crab...does it have pincher or and triangular head...is it hardshelled??

 

[rondaw3]

Looks morelike an anemone. Difintely not any type of crab. Will an anemone "swim" like a jellyfish if it is unattached to anything and floating around in the water?

 

[MedicineMan1]

Anenomes, IME, don't swim; they either crawl over the rock using their "foot" or they roll around in the current.

Any possibility it's an octopus? I'm grasping at straws here but that's about the only sea critter I can think of that would have 8 limbs and a central body like a spider that would float freely in the water column.

 

[wla20]

Any chance its a basket star or crinoid type thing or any kind of brittle starry thing? or perhaps one of those upside jelly fish (casseopia I think they're called). Probably wrong but thought it might be worth throwing in some possibilities.

Wayne

 

[MedicineMan1]

Wayne;
You're possibilities are much more likely than mine!

 

[Anonymous]

I'm thinking the medusa stage of a hydroid.

 

[Big_fish]

Could be an aiptasia. Aiptasia will swim if they detach and are swept into the water column. This is based on first-hand personal observation so it may not be reliable information

And it does take a jellyfish approach to aquatic locomotion.
HTH,
Scott

 

[Anonymous]

Medicine Man,
Anemones do in fact "swim" via septal retractor muscle contractions.

 

[some'n'smellsfishy]

this is stupid but it could be a jellyfish....just a suggestion