I was maliciously savaged by a flower urchin, Toxopneustes elegans, while diving off Okinawa. The beautiful colors and soft furry appearance of this urchin tempted me to take off my dive glove (what was I thinking....Not!) and extend my hand in a cross-species gesture of friendship. Fortunately, I remembered my flight-line training whereby touching a hot instrument probe with the palm would cause the hand to involuntarily close and sear flesh to a fare-thee-well, and I brushed the urchin slightly with the back of my hand. The pain was immediate and intense! It radiated up my arm and I felt like someone had my chest in a vise. My buddy and I terminated the dive post haste and by the time we returned to shore, I was also experiencing shortness of breath and nausea. We used meat tenderizer to try to neutralize any remaining stingers (found out these were called pedicellaria) and hot water from a nearby restaurant to take some of the pain. (Most marine venoms have a heat labile component that breaks down quickly when immersed in about 120 F water). There are no urchin anti-venoms and hospital treatment is mostly supportive. After a local painkiller, something to settle the stomach, and a 4-hour rest in the ER, I was good to go and had no lasting symptoms the next day.
There are a lot of fascinating critters out there and a number of them rely on chemical warfare for their defense. My hat is off to all of them but now my gloves stay on, thank you.
tj