im not sure if all zoanthids have the same toxin, but id bet they do...? the toxin contained within the zoanthid is called PALYTOXIN and is one of the most potent, and deadly toxins know to man at this time. way back in the day, tribal islanders used the toxin from zoanthids on thier spear tips to help kill prey while hunting.
a really sad story i heard of once, was about a guy getting ready for a frag swap. he had a bunch of different corals in buckets getting ready for transport. in one of the buckes were a bunch of zoanthids heading for the swap. sometime during the seperation of corals, the guys dog drank out of the zzoanthid bucket, and died shortly afterwards. the guy telling the story (who it happend to) said when he first noticed his dog was looking ill, it was only like an hour after the dog drank the water. he took the dog to the vet, they couldnt do anything, so he took the dog home, and the dog died like 7 hours later. i think from the time the dog drank the water, untill the time the dog died was only around 14 hours or something. alot of thoesdetails are probably way off, but i remember the dog had died almost within the same day as drinking the zoanthid water.
so yes, it is a very good idea to use protection when dealing with any coral! ive had experiences with swolen and itchy hands myself after placing and fragging corals bare handed. one time my lips actually started to itch. dont know exactly what brought that on?