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I’ve got two questions to ask you, thank you for spending the time to answer them.

I’ve been wondering. Do these organisms that you are finding reproduce using egg and sperm or do they perhaps reproduce in a different way? Also the pressure down where the hydrothermal vents are must be enormous. When you bring organisms up to study them wouldn’t the pressure change or deform them, and also affect your research on them?

Thank you.
Hyun Yui
7th grade
Mrs. Shields Class
Clarke Middle School, Lexington, Ma

Hi Hyun,
That’s a very good question. Most of the animals we find at the vents reproduce using egg and sperm, and most of them are different sexes, male and female. Surprisingly enough, vent animals reproduce very much like their shallow water relatives.

The interesting differences are found when we compare how they fertilize their eggs and how and where the embryos develop. For example, some animals fertilize their eggs internally (some worms and shrimp) and some have external fertilization (like the vent mussels). Also, some animals (like clams and tubeworms) have larvae that develop from eggs with lots of yolk that they can use for food, and others (like the mussels and shrimp) have larvae that develop quickly and must feed from other microorganisms in the water column.

As for pressure, it is mostly a problem when you bring animals to the surface that have gas spaces, like swim bladders of fish. Believe it or not, most of the animals that we collect have a harder time dealing with the increase in temperature (from 2 to 20¡C) than the change in pressure. That’s why we use insulated containers to collect animals so they arrive on the surface as healthy as possible. Some animals, however, like the crabs have some neurological problems at atmospheric pressure so they lose their coordination.

Thanks for taking such an interest in marine biology, it can be a lot of fun!

Shana Goffredi

Dear Crew,
Why do the shrimp crowd around or live right near a chimney?

Michelle and Heather C.A. Dunning

Hi Michelle and Heather:
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!

Thanks for writing!
Susan Humphris

Hello again, and this site gets better all the time.

I feel as if I’m on the ship with you all. I was interested in the DNA questions and answers and I was wondering is there any “bonding” differences in the DNA base pairs of organisms taken from great depths and pressures, and does the DNA maintain its integrity when taken to the surface; i.e., brought back to atmospheric pressure.

Also what is the pressure where these vents are ?

Regards from Bradford UK
Kieran Burns B.Sc......

Great question, Kieran!
Deep sea animals certainly must be able to tolerate great pressures (100 atmospheres increase for every 1000m depth). Thus, at the Indian Ocean vent sites, the pressures are ~300 atmospheres (or 300x what we experience at sea level on land).

The DNA molecule itself probably does not undergo any pressure adaptations in vent creatures, but the proteins that surround the DNA strands to maintain the helical structure most likely do. Proteins in general can be very adaptable to high pressures and many deep-sea animals have shown this. Pressure adaptations in deep sea animals are very fascinating and I encourage you to look into it further.

Thanks for exploring along with us via the website.

Shana Goffredi