Download File - Science with Mrs. Persico

HYDROTHERMAL VENTS AND CHEMOSYNTHESIS:
A HABITAT IN THE DARK
Hydrothermal vents are deep, dark locations on the sea floor which release high
temperature fluids and chemicals into the ocean water above. They are usually found in
areas of volcanic activity. Even though we might consider this to be a harsh environment,
hydrothermal vents are abundant with life. In fact, more than 300 species live around the vents and are unique
to this type of environment. These creatures include tubeworms, fish, crabs, shrimp, clams, and
chemosynthetic bacteria. These organisms have learned to survive in the complete darkness, the extremely
hot vent water and the tremendous water pressure.
Hydrothermal vents are so deep that light is unable to penetrate. Without light, plants are unable to
perform the process of photosynthesis. Therefore, plants are unable to form the basis of the food chain as they
do where light is available. Organisms in hydrothermal vents must acquire energy in another way. Animals at
these depths depend on bacteria that are able to convert chemicals such as sulfur found in the vent's fluids into
energy through the process of chemosynthesis. Larger animals then eat the chemosynthetic bacteria, or eat the
animals that eat the bacteria. In other vent creatures, the chemosynthetic bacteria live inside their bodies. Some
organisms, such as the tubeworms, that live around the vents do not have a mouth or even a digestive tract as
we do. The bacteria actually live inside their bodies and provide nutrients directly to the organisms' tissues.
ANALYSIS
1. What are the characteristics of a hydrothermal vent environment?
2. What type of organisms live in hydrothermal vents?
3. What type of organism normally forms the basis of all food chains?
4. Why are these organisms unable to survive in hydrothermal vents?
5. What do organisms in hydrothermal vents depend upon for energy?
6. What is chemosynthesis?
DIVING DEEPER: Photosynthesis vs. Chemosynthesis
All living things need energy. People and other animals get energy from the food they eat. However,
neither plants on land nor microbes that live around hot vents eat food. Instead, they make their own
food, and are called producers.
Plants harness energy from the sun to make sugars. This process is called photosynthesis. Organisms
that are photosynthetic use the sun’s energy to produce sugars from carbon dioxide and water, releasing
oxygen in the process.
Hot vent communities like the one found at the Endeavour Ridge Node, and methane seep communities
like the ones found at the Barkley Canyon Node are undersea ecosystems that thrive without sunlight.
Instead, these ecosystems get their energy from chemicals through a process called chemosynthesis.
Organisms that are chemosynthetic use chemicals as the energy source to produce sugars from carbon
dioxide, oxygen, and water.
TASK: Complete the following table to compare the process of photosynthesis to chemosynthesis.
Use the animation found on the Dive and Discover Website:
http://www.divediscover.whoi.edu/vents/light.html to help you learn the steps (1-4).
PHOTOSYNTHESIS
CHEMOSYNTHESIS
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PHOTOSYNTHESIS vs. CHEMOSYNTHESIS REVIEW
The prefix photo means light.
The prefix chemo means chemicals.
The word synthesis means to make.
1. Using the information above write a one sentence definition of
photosynthesis.
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2. Using the information above write a one sentence definition of chemosynthesis.
__________________________________________________________________________________________
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PHOTOSYNTHESIS vs. CHEMOSYNTHESIS REVIEW
The prefix photo means light.
The prefix chemo means chemicals.
The word synthesis means to make.
3. Using the information above write a one sentence definition of
photosynthesis.
______________________________________________________________
______________________________________________________________
4. Using the information above write a one sentence definition of chemosynthesis.
__________________________________________________________________________________________
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Examine the chemical equations for photosynthesis and chemosynthesis and follow the directions below.
Write the word equation for each on the line provided. (Hint: H2S = hydrogen sulfide and S = sulfur)
Photosynthesis:
CO2 + H2O + Light 
C6H12O6 + O2
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Chemosynthesis:
CO2 + O2 + H2S

C6H12O6 + H2O + S
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1. If the reactants and/or products are the same in each equations, cross them out. (This will help you identify
how the equations differ!)
2. Record the differing products and reactants in the table below.
Differing Reactants
Differing Product
PHOTOSYNTHESIS
CHEMOSYNTHESIS
Examine the chemical equations for photosynthesis and chemosynthesis and follow the directions below.
Write the word equation for each on the line provided. (Hint: H2S = hydrogen sulfide and S = sulfur)
Photosynthesis:
CO2 + H2O + Light 
C6H12O6 + O2
______________________________________________________________________________
Chemosynthesis:
CO2 + O2 + H2S

C6H12O6 + H2O + S
______________________________________________________________________________
1. If the reactants and/or products are the same in each equations, cross them out. (This will help you
identify how the equations differ!)
2. Record the differing products and reactants in the table below.
Differing Reactants
PHOTOSYNTHESIS
CHEMOSYNTHESIS
Differing Product