The Pompeii worm (Alvinella pompejana) is an extremophile species of worm which lives in the hot water around hydrothermal vents in the Pacific Ocean. This worm species can be found in thin tubes grouped together on the sides of th vents, close to the openings, where water from deep inside Earth pours out at temperatures of up to 350°C.
Because the Pompeii worm is one of the most heat-tolerant species on Earth, it has some adaptations to surviving these harsh conditions. What is interesting is that their tail ends are found resting in temperatures as high as 80°C, while their heads stick out of the tubes into water that is a lot cooler at just 22°C. It is thought that the chemosynthetic bacteria that form a hairlike covering on their backs which is up to 1cm thick, may provide them with protection from the extreme heat. Living in a symbiotic relationship, the worms secrete sugary mucus from tiny glands on their backs to feed the sulphur-eating bacteria, and in return, they are protected by some insulation. These bacteria are chemolithotrophic, contributing to the ecology of the vent community. The bacteria are thought to produce special enzymes which provide them and in effect the Pompeii worm, protection from a wide range of temperatures.
A Pompeii worm may survive exposure to hot water by dissipating heat through its head to keep its internal temperature within a suitable range for survival. The Pompeii worm pokes its head out of its tube home to feed and breathe in the cooler water. Its posterior end is exposed to extreme temperatures; the anterior end stays at a much more comfortable 22°C.