Friday, January 25, 2008
Fish that release poison to see off attackers
Stonefish, which are found on the sea bottom in warm, shallow waters, are among the most venomous of venomous fish. Like most others, such as weevers and toad fishes, they only inject their poisons in self-defence. It takes pressure from a predator - pressing down on one of the hollow spines along the stonefish's back - to release the poison, rather like a hypodermic syringe. The poisons are painful but rarely lethal.
The stonefish also defends itself by being perfectly camouflaged - as a rock. Partly buried under sand or mud, its disguise is enhanced by a covering of warty lumps that secrete a sticky substance to which small organisms become attached.