These worms play an integral part of the community. They do not have any digestive capacities, as they lack mouths and digestive systems. Rather, they absorb the nutrient-rich waste products of the bacteria through their epidermal layers. They use hemoglobin produced inside their bodies to combine hydrogen sulfide, which is a necessity of many of the bacteria living in and around the vents. The worms transfer this hydrogen sulfide to the bacteria upon contact, and in return, the absorb the nutrients being produced by the bacteria. Additionally, one study examining vents off the coast of South Africa also found the presence of a new species of nematode, known as Halicephalobus mephisto (Borgonie et al., 2011). There are also a number of annelids as well as typical crustaceans, like snails, crabs, and shrimp are often common (Edmonds et al., 2003). There are also species of fish and octopi that form some of the top predators on the unique deep water food chain. It is the presence of life in such extreme conditions that has often given rise to theories positing the early beginnings of life on earth. The presence of archaea in these extreme conditions shows that single-celled organisms that were our ancestors could have originated in similar conditions millions of years ago (Lemonick & Dorfman, 2002). Scientists now assert that life as we know it today began in a similar situation. Hot, mineral-rich water came spewing out of the inner core of the earth and created the environment for live to thrive and then later evolve into the myriad of species that are present today. This theory also opens up the questions about potential life on other planets. Contemporary astronomy has shown that other planets in our solar system also tend...

Europa, one of Jupiter's moons, has shown to have clear evidence that it features a number of hydrothermal vents, opening up the question whether there are similar biological communities also thriving in these distant worlds (Lemonick & Dorfman, 2002). Similar vents have also been found on Titan, one of Saturn's larger moons. As such, studying life around hydrothermal vents could paint a picture of alien life forms as well.
References

Borgonie, G., Garcia-Moyano, a., Litthauer, D., Bester, a., van Heerden, E., Moller, C., Erasmus, M., & Onstott, T.C. (2011).Nematoda from the terrestrial deep subsurface of South Africa. Nature, 474(June). 79-88. Doi: 10.1038/nature09974

Ericsson, Magnus. (2008). Seabed deposits generate a new wave of interest in offshore mineral recovery. Offshore Mining (September).

Edmonds, H.N., Michael, P.J., Baker, E.T., Connelly, D.P., Snow, J.E., Langmuir, C.H., Dick, H.J.B., Muhe, R., German, C.R., & Graham, D.W. (2003). Discovery of abundant hydrothermal venting on the ultraslow-spreading Gakkel ridge in the Arctice Ocean. Nature, 421(16).

Lemonick, Michael D. & Dorfman, Andrea. (2002). Microbes at the extremes may tell us how life began. Time Europe, 160(6), 34-38. http://search.ebscohost.com/login.aspx?direct=true&db=f5h&an=7091367&site=ehost-live

Spotts, Pete. (2010). At deepest hydrothermal vent yet found, an 'awe-inspiring' view. Christian Science Monitor. http://search.ebscohost.com/login.aspx?direct=true&db=f5h&an=49106085&site=ehost-live

USA Today Magazine. (2012). Life discovered on dead hydrothermal vents. USA Today. June 2012.