Image: DONAL T. MANAHAN

Ever since their discovery in the late 1970s, the creatures that dwell in the hot, sulfurous hydrothermal vents of the deep sea floor have captivated marine biologists. Yet despite nearly 25 years of study, one question in particular has eluded them¿namely, how do the larvae of these vent fauna disperse and colonize new vents, which can lie hundreds of kilometers away? Now new findings, published in the current issue of the journal Nature, are finally shedding light on the matter.

To assess how long the larvae live and how far they can travel, Donal T. Manahan of the University of Southern California and his colleagues studied larvae of the giant tube worm Riftia pachyptila (right). After collecting specimens from Pacific Ocean sites, the team reared tube worm embryos to the larval stage by replicating the temperature and pressure conditions of the worm's natural environment, and closely monitored their development. The typical tube worm larva, they determined, has a potential lifespan of about 38 days, which is apparently enough time to get to another vent and settle down before running out of food.

To reach the next vent, the larvae apparently hitch a ride in neutrally buoyant plumes that are created by the mixture of hot water from the vents and the deep ocean's cold water. From there, they let the current deliver them to a new home. Knowing the lifespan of the larval tube worm and the current conditions at other hydrothermal vent sites should thus enable researchers to predict tube worm dispersal, team member Lauren Mullineaux of the Woods Hole Oceanographic Institute says.

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