We have spent over 40 hours on the seafloor with ROV Jason mapping, studying and exploring the newly-discovered Edmond hydrothermal vent field since Friday. It’s the longest stretch of time ROV Jason has spent on the seafloor during this expedition.

During the long hours scientists in the Control Van have observed many differences in vent communities living at the Edmond and the Kairei hydrothermal fields.

To explain the biological differences between the fields, scientists point to several possible factors. Several jogs in the path of the Central Indian Ridge between Edmond and Kairei could limit the migration of some vent animal larvae. Also, Edmond is 1,000 meters deeper than Kairei. The fluid chemistry and the ways the fluids flow out of the seafloor are different. At Edmond, there is much more diffuse flow but there are still many tall black smoker chimneys.

Consider the weird white fish biologist Shana Goffredi saw tonight on Jason’s video cameras. These ghostly creatures that resemble swimming sport socks were scarce at Kairei. Yet they lurk here by the dozens. Sea cucumbers, with their translucent bodies, also are found at Edmond, but not Kairei. The same is true for a brown tube-dwelling worm we found in the sediment.

But where are the hairy snails, those shelled beasts so abundant at the Kairei site? “We’ve only seen three here,” said Shana. “And we don’t have nearly as many mussels as we did at the other site.” Ditto for limpets, a type of little mollusk with a pyramid-shaped shell.

We will spend our five remaining days uncovering reasons for these differences between Kairei and Edmond. Some of these questions may be answered here; others will be addressed in our science labs once we take the samples home. And still others will remain for future expeditions in the months and years to come.

It’s a scenario Geologist Dan Fornari knows well. He has participated in dozens of oceanographic expeditions and knows that sometimes, the last few days of a research cruise can be the most important.

“Sometimes you have to deal with the disappointment of not finishing your work. Other times you find the key to unanswered questions just in the nick of time,” said Dan. “Everyone is tired and wanting to be home, but part of us also wants to stay.”

Despite a month at sea of round-the-clock work, Dan said “there is never enough time to do all the work out here, and always more data to collect that will help answer our questions.”

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