A toxic paradise: Poisonous sea creatures

Marine life is very prolific. Incredibly diverse creatures live, feed and compete for space in the water, on rocks, among reefs and on the sea bed. Many defend themselves, protect their territories and sometimes even hunt their prey by deploying an amazing array of bioactive and toxic products. The marine environment is a vast reservoir of biochemical diversity. Although many of these substances are potently toxic, some offer opportunities to identify new drugs. There are probably several thousand poisonous or venomous marine organisms. In his 1965 review of toxic sea life, Findlay Russell claimed to have identified around 1000 species; in 1984, he revised this to 12001. This has been comfortably exceeded and now represents a substantial underestimate. These animals are drawn widely from the spectrum of marine fauna, ranging from unicellular protists through to vertebrates. More than 1000 species of fish possess venomous spines either in their fins or on their operculum (gill covers) and tail. This article will take a gentle swim around just a few of the poisonous creatures that inhabit our seas and offer a taste of the physiology, pharmacology and biochemistry associated with the toxins that they possess.