July 10 – In Hot Water

Today’s factismal: Sharks have been seen swimming around in a volcano!

There is a joke in science that astrobiology is the only topic without a subject. (Hey, that one gets big laughs at the meetings!). Like all good jokes, it is both true and untrue. It is true because we have never found incontrovertible proof of life anywhere but on Earth. And it is untrue because of all of the places that we’ve found life on Earth, places where we never thought to find it. We’ve found earthworms living two miles deep in solid rock. We’ve found fish living seven miles under water. We’ve found bacteria floating 30 miles high in the atmosphere. We’ve found critters that live in absolute darkness in sub-zero salt water. And perhaps most amazing of all, we’ve found sharks that like to swim in active volcanoes.

A shark swimming in hot, acidi water inside a volcano (Image courtesy National Geographic)

A shark swimming in hot, acidi water inside a volcano
(Image courtesy National Geographic)

While on a routine expedition to an underwater volcano known as a seamount, a National Geographic team sent a remote controlled camera down to record the conditions inside the caldera of the volcano. This was more dangerous for the camera than it sounds because the caldera is the part of the volcano where the lava erupts; water inside a caldera can easily reach 450 F and be more acid than vinegar. What they expected to find was plumes of super-heated water filled with minerals like sulfur and iron. And they found them. They thought that they might find some small critters, like the tube worms that surprised the Alvin crew on their first dive to a ridge in 1977. And they saw those, too. But what they didn’t expect to see was sharks, rays, and other fish, swimming around and having a good old time. But that’s exactly what they saw!

Titan with the moon Enceladus peeking out from behind. (Wait. That's no moon!) (Image courtesy NASA)

Titan with the moon Enceladus peeking out from behind.
(Image courtesy NASA)

This is important to astrobiologists because up until now, people have thought that large life could only exist within a fairly narrow set of conditions. But this pure research has shown that life is a lot more adaptable than we thought. Instead of just finding bacterial mats and slime living in places such as the subsurface oceans of Europa or the hydrocarbon pools of Titan or the hidden oceans of Pluto, we might actually find critters big enough to see without a microscope. And astrobiologists might finally have a subject to go with their topic.

The egg case of a catshark (Image courtesy Adolphe Millot)

The egg case of a catshark
(Image courtesy Adolphe Millot)

The egg case of a bullnose shark (Image courtesy Adolphe Millot)

The egg case of a bullnose shark
(Image courtesy Adolphe Millot)

Of course, if you want to start hunting for exotic life of your own, why wait for the next trip to Pluto or Europa? Why not head for the sea shore and hunt mermaid’s purses? These egg cases can tell us a lot about the number and types of sharks living in an area. To learn more about mermaid’s purses and report your finds, head over to the Great Egg Case Hunt:
http://www.sharktrust.org/en/great_eggcase_hunt/

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