was testing why my leds were not turning on and spotted it floating...at first thought it was a baby brittle, but it pulled it's legs in like a person doing a cannonball into a pool and then extended it's legs again. I watched it for quite a while and decided to suck it out. Looks pretty cool with the orangy legs.
There are crustaceans called sea spiders. I've caught them locally. Its hard to tell from your pic though. You can bring it over to get a better pic as Jon has suggested. Just shoot me a PM.
sorry...it's dead. Maybe from heat or starvation. Can deliver the remains for classification.
It's most likely a sea spider (long-legged) not the mite-looking zoa-eating spiders after doing some research.