How do tube worms move between different hydrothermal vents?

Helen - That's a great question. These wonderful two metre long creatures are giant tube worms that live in the middle of the ocean, very deep down in the deep dark ocean where there's no connection to the light and they only survive because they have this symbiotic bacteria that harness chemicals that live inside them. How do they move from one vent to another? They do live in very clustered environments a long way apart from each other. There've been a couple of different studies that look at the genetics and first of all they found out how long their larvae can live for. One theory is that they have eggs and sperm. We can see them fertilising externally, outside of the worm. They form larvae and in the laboratory those have lived for 38 days. The idea is that that's enough time for them to hitch a ride on a plume of water. We know there are these nutrient buoyant plumes of a mixture of hot and cold water very deep down, we're talking km down in the middle of the Pacific Ocean. That's enough time for them to drift and find another vent for them to live on. These are also very short-lived things. These hydrothermal vents come and go as changes in the sea floor take place. Really they're quite ephemeral and that's one thing that they've done. Genetics are likely to be what happens. You've got very distinct populations that are fed by just a few larvae arriving and starting a new population as new vents open up black smokers and things like that. We're talking 400 degrees centigrade. Crazy ecosystems.