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Chemosysthesis in the Classroom

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Chemosysthesis in the Classroom Gulf of Mexico Exploration Chemosysthesis in the Classroom FOCUS Polychaete worm Chemosynthetic bacteria Phylum Chemosynthetic bacteria GRADE LEVEL Hemoglobin 9-12 (Chemistry/Biology) Gills Vinogradsky column FOCUS QUESTION What changes affect succession in the development The key words are integral to the unit but will be of chemosynthetic bacterial communities? very difficult to introduce prior to the activity. They are really the material of the lesson. There are no LEARNING OBJECTIVES formal signs in American Sign Language for any Students will observe the development of chemo- of these words and many are difficult to lipread. synthetic bacterial communities. Having the vocabulary list on the board as a refer- ence during the lesson will be extremely helpful. It Students will recognize that organisms modify their will also be very helpful to copy the vocabulary list environment in ways that create opportunities for and hand it out to the students to read after the les- other organisms to thrive. son to reinforce what was covered as the six week project continues. Students will be able to explain the process of che- mosynthesis. MATERIALS Directions for setting up Winogradsky columns Students will be able to explain the relevance of from http://topex-www.jpl.nasa.gov/education/activities chemosynthesis to biological communities in the Black mud from a local river, lake, or estuary, vicinity of cold seeps. approximately 500 ml for each student group Water from the same source used to obtain black ADDITIONAL INFORMATION FOR TEACHERS OF DEAF STUDENTS mud, approximately 3 liters for each student group In addition to the words listed as key words, the fol- 500 ml graduated cylinder, two for each student lowing words should be part of the vocabulary list. group Oxidizing Calcium sulfate (Plaster of Paris), 80 g for each Hydrogen sulfide student group Hydrocarbon gases Seep 500 ml jar or beaker Sediment Stirring rod Continental margins Straw or small pieces of filter paper, 50 g for Methane each student group 1 Gulf of Mexico Exploration—Grades 9-12 (Chemistry/Biology) Gulf of Mexico Exploration—Grades 9-12 (Chemistry/Biology) Chemosynthesis for the Classroom oceanexplorer.noaa.gov oceanexplorer.noaa.gov Chemosynthesis for the Classroom Sodium bicarbonate (baking soda), 4 g for each a process called chemosynthesis (in contrast to student group photosynthesis in which sunlight is the basic energy source). Some chemosynthetic communities have Crushed multivitamin pill, one for each student been found near underwater volcanic hot springs group called hydrothermal vents, which usually occur Plastic wrap along ridges separating the Earth’s tectonic plates. Rubber bands Hydrogen sulfide is abundant in the water erupting Source of artificial light from hydrothermal vents, and is used by chemosyn- Tape and markers for labelling graduated cylin- thetic bacteria that are the base of the vent com- ders munity food chain. These bacteria obtain energy by Flashlight with red cellophane over lens oxidizing hydrogen sulfide to sulfur: Optional: microscopes and materials for making CO2 + 4H2S + O2 > CH2O + 4S +3H2O wet mounts (carbon dioxide plus sulfur dioxide plus oxygen yields organic matter, sulfur, and water). Visit http: AUDIO/VISUAL MATERIALS //www.pmel.noaa.gov/vents/home.html for more information None and activities on hydrothermal vent communities. TEACHING TIME Other deep-sea chemosynthetic communities are One 45-minute class period to set up columns, found in areas where hydrocarbon gases (often approximately 15 minutes at weekly intervals for methane and hydrogen sulfide) and oil seep out of six weeks to make observations, and one 45-min- sediments. These areas, known as cold seeps, are ute class period for presentation and discussion of commonly found along continental margins, and results (like hydrothermal vents) are home to many species of organisms that have not been found anywhere SEATING ARRANGEMENT else on Earth. Typical features of communities that Groups of four students have been studied so far include mounds of fro- zen crystals of methane and water called methane MAXIMUM NUMBER OF STUDENTS hydrate ice, that are home to polychete worms. 20 Brine pools, containing water four times saltier than normal seawater, have also been found. KEY WORDS Researchers often find dead fish floating in the Cold seeps brine pool, apparently killed by the high salinity. Methane hydrate ice Chemosynthesis Where hydrogen sulfide is present, large tube- Brine pool worms known as vestimentiferans (formerly clas- Vestimentifera sified within the phylum Pogonophora; recently Trophosome Pogonophora and Vestimentifera have been includ- Succession ed in the phylum Annelida) are often found, some- times growing in clusters of millions of individuals. BACKGROUND INFORMATION These unusual animals do not have a mouth, stom- One of the major scientific discoveries of the last ach, or gut. Instead, they have a large organ called 100 years is the presence of extensive deep sea a trophosome, that contains chemosynthetic bac- communities that do not depend upon sunlight as teria. Vesti-mentiferans have tentacles that extend their primary source of energy. Instead, these com- into the water. The tentacles are bright red due munities derive their energy from chemicals through to the presence of hemoglobin which can absorb 2 3 Gulf of Mexico Exploration—Grades 9-12 (Chemistry/Biology) Gulf of Mexico Exploration—Grades 9-12 (Chemistry/Biology) Chemosynthesis for the Classroom oceanexplorer.noaa.gov oceanexplorer.noaa.gov Chemosynthesis for the Classroom hydrogen sulfide and oxygen which are transport- cess requires energy; photosynthesizers obtain ed to the bacteria in the trophosome. The bacteria this energy from the sun, while chemosynthesiz- produce organic molecules that provide nutrition to ers obtain energy from chemical reactions. Point the tube worm. A similar symbiotic relationship is out that there are a variety of chemical reactions found in clams and mussels that have chemosyn- that can provide this kind of energy. Contrast thetic bacteria living in their gills. Bacteria are also hydrothermal vent communities with cold-seep found living independently from other organisms communities. Visit http://www.bio.psu.edu/cold_seeps for in large bacterial mats. A variety of other organ- a virtual tour of a cold seep community. isms are also found in cold seep communities, and probably use tubeworms, mussels, and bacterial 2. Have each student group follow procedures mats as sources of food. These include snails, eels, given at http://topex-www.jpl.nasa.gov/education/activities sea stars, crabs, lobsters, isopods, sea cucumbers, for setting up two Winogradsky columns using and fishes. Specific relationships between these locally-collected black mud. Cover each column organisms have not been well-studied. tightly with plastic wrap and secure with rub- The Gulf of Mexico contains the largest reservoir of ber bands. One column should be placed in fossil fuel in the continental U.S., and the geology a darkened area and the other column near a of the area has been intensively studied for more light source (but not in direct sunlight). Students than 50 years. While should observe their columns weekly, and record cold seep communities were discovered in the Gulf their observations. You may have them make wet more than 20 years ago, the biology of these com- mounts for microscopic examination at the end munities has been studied at only three sites less of three and six weeks. Use appropriate safety than 20 km apart. Exploring for new cold seep precautions when making wet mounts, includ- sites and studying the biology and ecology of the ing gloves, antibacterial solution for disposing of organisms that live there is the focus of the Ocean slides, and hand washing following completion Exploration 2002 Gulf of Mexico Expedition. of the activity. This activity focuses on chemosynthetic bacteria 3. Have each group present and discuss their similar to those that are the base of food webs in results. Students should have observed a series cold seep communities. Black mud from a local of changes in the appearance of the mud in the water body is incubated in a glass cylinder (called columns caused by a succession of bacterial a Winogradsky column) with a source of chemi- species. They should infer that changes caused cal energy (calcium sulfate) and organic mate- by one species (for example, the production of rial (straw or filter paper) to grow a succession waste products) create opportunities for other of chemosynthetic bacteria over a period of six species. Similarly, changes in the chemical com- weeks. This activity was originally developed by the position of the mud, such as formation of hydro- Orange County Marine Institute/San Juan Institute gen sulfide, alter the environment in ways that Activity Series, and is available on NASA’s Jet may favor the growth of other bacterial species. Propulsion Laboratory Ocean Planet website at The processes observed in the Winogradsky col- http://topex-www.jpl.nasa.gov/education/activities. umns roughly models the development of deep- sea chemosynthetic communities. Ask the students LEARNING PROCEDURE to speculate about what other organisms might 1. Lead a discussion of deep-sea chemosynthetic appear in the community if these processes were communities. Contrast chemosynthesis with pho- taking place in the area from which the mud was tosynthesis. In both processes, organisms build collected. sugars from carbon dioxide and water. This pro- 2 3 Gulf of Mexico Exploration—Grades 9-12 (Chemistry/Biology) Chemosynthesis for the Classroom oceanexplorer.noaa.gov THE BRIDGE CONNECTION http://www-ocean.tamu.edu/education/oceanworld/resources/ www.vims.edu/BRIDGE/vents.html – Links to other ocean-related web sites THE “ME” CONNECTION Paull, C.K., B. Hecker, C. Commeau, R.P. Feeman- Have students write a short essay on why cold Lynde, C. Nuemann, W.P. Corso, G. seeps might be directly important to their own lives. Golubic, J. Hook, E. Sikes, and J. Curray. You may want to offer a hint that perhaps the ener- 1984.
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