May 15–June 3, 2005
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Today was the last dive, Jason II dive number 153 and the 14th of this expedition. On the left, you can see Jason coming back aboard at the end of the dive. Under the expert control of Will, the Jason pilot, Jason’s robotic arm carefully scooped a net full of Alviniconcha snails that were located next to the hot discharge. Some of the snails rolled out of the net and escaped the immediate threat of collection and tumbled down the talus slope. White crabs in a feeding frenzy scurried down after these helpless snails. When the snails are “at home” around the vent, they are less susceptible to the ravaging crabs. Once disturbed, that snail’s destiny is final. Shana is anxious to examine the snails for symbiotic bacteria.
Shana Goffredi studies the symbiotic relationships between invertebrate hosts and symbiotic bacteria. In this case Alviniconcha and Ifemeria snails are host to the bacteria that reside in their gills. The snails provide the bacteria with a place to live, and the bacteria produce food and other nutrients for the snails. Shana is studying juvenile snails, attempting to determine at what age they acquire their critical bacteria. The snails will not allow just any type of bacteria to settle within their tissues. They are very specific. How host and symbiont recognize each other is another of the many mysteries that interest Shana.
Deep-sea vent symbiotic relationships are difficult to study for obvious reasons of location and access. Our understanding of these unique associations is sketchy at best. The great thing about symbiotic relationships is that it allows organisms to exploit niches that they other wise could not. Shana found a limpet with frilly external foot flaps. These soft tissue areas appear to be colonized by epibionts (epi means to live on or above, and biont is a term for living “thing.”). This relationship may or may not be symbiotic. Shana will question and hopefully find the answer using the scientific method.
As soon as Jason II is safely onboard the science team will take the samples into the lab for processing them one last time. (It almost seems like a human feeding frenzy over the samples that Jason has collected). There seems to be a faint sadness that the hard work and excitement is drawing to a close. On the other hand, most are anxious to return to home and loved ones.
This expedition has been made possible by National Science Foundation grants to Dr. Robert Vrijenhoek (NSF OCE-0241613) and Dr. Cindy Van Dover (NSF OCE-0350554)