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Unformatted text preview: • right photos) is free living and forms colonies about 1­3 mm in size. Richelia (lower right) is a cyanobacterium which lives inside of diatoms, another type of unicellular phytoplankton The pairing of the diatom and Richelia is called a symbiosis Symbiosis Symbiosis • The term symbiosis, simply means two different • • • organisms living together. There are different types of symbioses Mutualism, a relationship in which 'members of two different species benefit and neither suffers. (+ +) Commensalism, a relationship in which 'one party gains some benefit, while the other suffers no serious disadvantage(+ 0) Richelia­diatom symbiosis is a Richelia­diatom symbiosis is a mutualism relationship…both benefit • The cyanobacterium • Richelia is able to fix N2, and provides the fixed N for the diatom. The diatom provides buoyancy for the Richelia and keeps it up in the euphotic zone where it has enough light energy for photosynthesis and N2 fixation. This is a bloom of Trichodesmium in Capricorn Channel of This is a bloom of the Great Barrier Reef. Photo taken from the Space Shuttle and is about 70 km across. This organism is very important in tropical waters through the process of N2 fixation. Why do marine biologists refer to a Why do marine biologists refer to a high accumulation of phytoplankton as a “Bloom” ? • This is because German...
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This note was uploaded on 11/07/2011 for the course BIO 160 taught by Professor Dr.jonstern during the Fall '08 term at S.F. State.

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