Earth Science: Geology, the Environment, and the Universe

Chapter 22: The Precambrian Earth

Problem of the Week

Hydrothermal Vent Communities

The basic building blocks of life, amino acids, have been found at deep-sea hydrothermal vents. Because of this, some scientists hypothesize that primitive forms of life may have originated in similar environments during the Precambrian. Other scientists disagree, saying that life could not have formed in the harsh environmental conditions that exist at these vents.

What is so harsh about the deep-sea hydrothermal vent environment? The main obstacles to common life forms, would be:

1. the hot water seeping down into Earth’s crust is laden with dissolved toxic chemicals, such as hydrogen sulfide, a colorless gas that is very toxic


2. the heated water emerging from the vents can be as hot as 350ºC


3. at the depths that hydrothermal vents are found, the pressure is extremely high


4. finally, due to depth, hydrothermal vents exist in total darkness

Getting past these hurdles might be easy for a simple life form, as would have existed in the early oceans of Earth, but these conditions are much greater challenges for more complex forms of life. Interestingly though, life does exist at hydrothermal vents. In 1977, research submersibles discovered an amazing variety of creatures. The deep-sea hydrothermal vents are home to entire unique communities, and these have since been found at several hundred locations in the deep oceans around the world.

Think About This:

Think about the most common forms of life. The majority of familiar life forms have fairly similar environmental requirements. Think about these requirements and answer the following questions.

-What provides the energy for life (the basis of the food web) as we commonly know it?

-What gases are necessary, either in the air or in the water?

-What is the range above and below sea level in which most life exists?

Therefore, what atmospheric pressures are most life forms subjected to?

-What is the temperature range in which most life exists?

Problem:

The conditions at present-day hydrothermal vents are not the same as the conditions that are believed to have existed in Earth’s early oceans and atmosphere. However, imagine the challenges to the development and existence of life in both environments. You will compare the environment and life forms thought to be present in Earth’s early oceans to life as it exists in today’s deep-sea hydrothermal vent communities.

Work in small groups to answer the following questions.

1. Four basic questions were asked in the Think About This section. Answer the same questions for the organisms you would imagine might exist in a deep-sea hydrothermal vent environment.


2. From your answers, create (describing, drawing, sculpting, ete.) an organism, food chain, or community that has adaptations, biological features, and any other characteristics that would allow them to exist in the deep-sea hydrothermal vent environment.


3. Share your creations with the other groups in your class. Discuss the different ideas of the other groups. Make a class list of adaptations that you and your classmates believe would benefit organisms that live in a deep-sea hydrothermal vent community.


4. Find out how close your creations come to the real life organisms of deep-sea hydrothermal vent communities. Then discuss your findings. Use the following Web sites.
   1. Hydrothermal Vent Communities -At this site you will find a lesson that has many links to resource sites about vents, conditions at vents, vent food webs, and vent life forms.
   
   
   2. What Are Deep-Sea Hydrothermal Vents? -At this site there is an explanation of what vents are, where vents are found, why research of vents and vent communities is important, and there is a discussion of the challenges faced by the organisms that live there.