In the ep where Skipper felt the mini-statue of Kona was out to get him there is a scene where Gilligan is taking trinkets out of Skipper's sea chest. ne trinket is an old bottlecap Gilligan then puts something on his own hand and asks Skipper what it reminds him of. Skipper says "Nothing. It must have just crawled in there." Is it a spider the First Mate is holding?

Yes,it's a spider...I really like that scene when Gilligan try to get the ring off the Skipper's finger:
The professor:Skipper!Who's your head?
The Skipper:I don't know about my head but,my finger is killing me!!!