More info on the sting
Most people do not have an adverse reaction to such a sting, although some people may experience pain or swelling after contact. The main purpose of these nematocysts seems to be feeding; the frilly tentacles where the stinging nematocysts are located are on the underside near the mouth. Nematocysts are highly specialized cells which fire a tiny dart when disturbed. This is what gives the tentacles a "sticky" feeling. These darts will attach to the prey (or other intruder) and pump toxins into them. Nematocysts also occur in anemones and many corals and are an effective method of capturing prey and discouraging predators.
Good info. link
http://www.centralpets.com/animals/f...s/swi1782.html