ABSTRACT
Sea urchins (class: Echinoidea) and starfishes (Asteroidea) belong to the animal phylum Echinodermata which also include brittle stars (Ophiuroidea) and the sea cucumbers (Holothuroidea). Although most echinoderms are poisonous, containing a variety of toxic substances in their body such as steroid glycosides or terpenes, only a few are able to cause injuries or envenoming symptoms in humans; namely one starfish, the crown-of-thorns starfish Acanthaster planci and various sea urchin species. Sea urchins possess two types of venom apparatus: spines and pedicellariae. Pedicellariae of most sea urchins are not able to penetrate the human skin; however, those of some species are extraordinarily large and able to inject venom even through human skin. Most injuries caused by the crown-of-thorns starfish and by sea urchins occur by stepping on them. Leaving the water immediately and removal of the broken spines or of the pedicellariae still hanging on the skin by forceps are the main first aid treatment recommended.
