National Geographic has a new feature online about evolution in hydrothermal vents. A team of researchers explored an isolated group of vents on the Mid-Atlantic Ridge and found many unique species there.
The organisms have many interesting adaptations like shrimp that do not have eyes, but have a sort of eyespot on their thoraxes that can sense infrared light. All of the species have to be adapted to the extreme temperatures and high pressure since the vent is nearly 9850 feet (3 kilometers) below the surface of the ocean. Since it is so deep, there is no light, hence the need to be able to see infrared wavelengths. The hydrothermal vent is very much like a volcano, making the environment even more intense for the individuals that live there.
The extreme hot temperatures lead to a relatively fast rate of evolution. Much like the report about global climate change speeding up evolution, the change in the hydrothermal species is thought to be even faster. Much more research needs to be done before any reports are finalized.