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Enjoyed your lecture and am enjoying following the dive.

Dorothy Lee
Setauket, N.Y.

Dear Dorothy Lee,
Indeed we have found shrimp! And they are so much like the shrimp on the Mid-Atlantic Ridge that I found myself forgetting that we are in the Indian Ocean. The IO shrimp look identical to the Atlantic species, but we have to do detailed morphological and molecular characterizations to confirm that they are or are not the same species. Behaviorally, too, the shrimp are extremely similar. Like the Atlantic shrimp, the IO shrimp are found in swarms of more than 1500 individuals per square meter on the sides of sulfide chimneys.

While the Kairei Field here on the Central Indian Ridge has a strong Atlantic vent character, we (and the Japanese scientists before us) also see species familiar from Pacific vents, including hairy gastropods and stalked barnacles. There is even more to be gleaned about biogeographic relationships among Atlantic, Indian, and Pacific vent faunas from the smaller, less charismatic animals -- especially the small worms. It is all fascinating.

Do invertebrates brought up from 2000+ meters expand? In general, no. In fact, the shrimp and other animals come up alive, if we take care to keep them cold during the ascent. Where expanding gas is an issue is in those species that have gas-filled volumes. Do you know what a swim bladder is in a fish? It’s what fish use to control their buoyancy. Vent fish and other deep-sea fish have swim bladders. These do expand during ascent and the fish arrive on the surface dead.

Do vent crabs like smelly fish? You bet! We often bait crab traps with old fish so that the odors attract the crabs. The crabs here seem to especially like the smell of a freshly killed mussel. We sometimes crush mussels while sampling them with Jason’s manipulator. It isn’t too long before we see the crabs come in to feast on the free meal.

Have you also wondered who eats the swarming shrimp? Those beautiful, innocent-looking anemone beds that surround the shrimp swarms here are made up of voracious carnivores. The anemones capture unwary shrimp by stunning them with nematocysts and then drawing the shrimp inside their mouths. When Jason stirs up a cloud of shrimp at the base of the swarm, near the anemone bed, some of the shrimp inevitably get tangled up in tentacles and consumed. It’s not quite the same “nature-in-action” shot as a lion capturing a zebra, but I am always impressed by the voracity of the sea anemones.

Dorothy, thanks for your interest. I’m glad we “met” at Stony Brook.

Cindy Van Dover

Hi -
My family and I have enjoyed the website and all the interesting questions and answers about the cruise. We were wondering about the crew of the ship and who actually runs the ship. Do the scientists steer the ship?

Thank you,

Lucy Foster,
Woods Hole, MA

Hi Lucy,
I am so glad you asked that question. The ship is steered by many different people. When the ship is docking, I steer. When we are coming in or out of a harbor, our Able Bodied Seaman steers because they have practiced steering many times and are very good at it. When we are out at sea. the Ordinary Seamen steer, that is where they get their practice. When we are recovering scientific instruments from the sea, the Mate on watch steers.

Maybe you would like to steer? Come to sea with us someday and give it a try.

For now I think you could start practicing in your home waters in Woods Hole, MA

Best Regards,
Capt. AD

In the journal entry for April 8th you mention that the Thermophiles are being used in genetic research. What types of genetic research are these?

Thanks,
Christy Barber.

Hi Christy:
Most genetic research now relies on making many copies of pieces of DNA called genes. Enzymes from thermophiles that were obtained from deep-sea hydrothermal vents and hot springs like in Yellowstone, have made this possible. These enzymes are called polymerases, and one of the deep-sea vent polymerases is called “deep-vent polymerase”. We use the enzymes in our own lab, to try and identify the microbes we obtain from the vent here on this cruise. Like detectives using genetic methods to try and identify criminals, we look for a specific gene that identifies our organisms. This way we are finding hundreds of new species of microbes that have never been seen before!

Anna-Louise Reysenbach

Hi:
This is Christian from Wenatchee High School again asking if the weather patterns you showed in the daily update will this affect your work in the ocean?

Hi Christian:
Weather is always a factor we consider when we are working out on the ocean. In fact, as I write this, we have strong winds and the ocean swells are probably up to 20 feet! The ship is both pitching and rolling, and we have everything tied down to stop it sliding or falling.

For Jason operations, the most critical time is when we want to launch or recover the vehicle or the elevator. Lifting equipment in and out of the ocean over the side of the ship is extremely difficult because the ship’s movement can cause the equipment to swing and bump into the ship, even when it has lines tied around to control it.

The Captain and the ship’s crew keep a sharp eye on the weather at all times and get frequent updates in a number of ways. For this cruise, we are receiving weather maps and information from four places: South Africa via e-mail, from NOAA (National Oceanic and Atmospheric Administration) satellites, from Reunion Island, and from the US Navy in Yokosuka, Japan. In addition, we are receiving phone calls from Yokosuka any time that they think we should be aware of any developing bad weather.

If you are interested, there is a web site that you can visit: www.yoko.npmic.navy.mil/

Being a very remote part of the ocean, we also try to do our part to help with weather forecasting by sending weather information to the Typhoon Center in Reunion. This provides them with one more set of observations that they can use in their predictions.

Hope you will continue to follow our expedition - thanks for the question!
Susan Humphris

Town: Rutland
State: MA
Question: What is it like underwater, when there are high waves?

Hi there:
Waves generated by the wind affect water near the surface only. There is something we refer to as the “wave base” below which the surface waves cannot be felt. The depth of the wave base varies depending on how big the waves are.

That means that a submersible, such as Alvin, does not feel the action of the waves at the bottom of the ocean. As you know, the Medea -Jason system that we are using is attached to the ship with a long fiber optic cable. The ship is going up and down in response to the waves. Medea’s role is to decouple Jason from the ship’s motion. That means that Medea goes up and down with the ship, and takes care of the tether that Jason is on. Jason can then move about on its tether without feeling the effects of the waves.

To learn more about the Jason-Medea system, go to About the Cruise and OceanographicTools on the website!

Thanks for the good question!
Susan Humphris

Hi my name is Stacy Misiak and I was wondering why shrimp surround hydrothermal vents? Is there a specific reason or is it something that is trying to be figured out.

Thank you very much

Hello again, Stacy:

That’s a really good question! Tim Shank, our shrimp expert on board, helped me with this one.

Shrimp live around vents because that is where there is lots of food and they can maintain large populations. The shrimp have appendages that allow them to scrape material and then “brush” it into their mouths.

They scrape material from two places. The first place is the chimney walls - you can see in the videos on the web site that they crowd around the surfaces of the chimneys. The chimney walls are made of sulfides, but they must also have bacteria living in the walls. The shrimp scrape the wall material into their mouths and digest the bacteria. The second place is their own bodies! The shrimp “farm” bacteria on their “exoskeletons” (or what you think of as the soft shell that you peel off before you eat shrimp). They help the bacteria grow by staying around the vents in the environment that the bacteria like. And then the shrimp scrape them off and eat them!

Hope you will continue to follow the expedition!
Susan Humphris

Hello,
When you answered a question a few days ago, you mentioned that you work in water that is 1.4 degrees C. Is the water colder just because it is deeper down? Or is it Antarctic water?

Thank you and good luck,
Jack Lindsay,
Massachusetts

Hello Jack:

The circulation of water in the deep ocean is driven by density differences. The density of seawater depends mostly on temperature and salinity, so the densest waters flow at the bottom of the ocean.

To make water denser, you have to either decrease its temperature or increase its salinity. Although both happen in different parts of the world, the water flowing below about 1000 m is mostly derived either from the Antarctic or at high latitudes in the North Atlantic. In these areas, the surface water is cooled and sinks into the deep ocean and then begins to circulate. Hence, it is the origin of the water, rather than its depth, that is the reason it is so cold.

Thanks for a good question - hope you will continue to follow along!
Susan Humphris