BIO 2137 Lecture 5: 5 - Protists (Algae and heterotrophic)
18 Oct 2016
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Single cells eukaryotes evolved 1. 8 billion years ago. Inward folding of the plasma to make nucleus. Protists evolved from prokaryotes around 1. 8 billion years ago. Lack leaves, roots, flower, seeds but may have specialized tissue. Different groups has different pigments or chloroplasts structure, indicating several endosymbiotic origins. Phytoplankton = microscopic algae and cyanobacteria suspended in the water column. Phytoplankton is the ultimate energy source for most marine/aquatic species. Also important in chemical cycling - co2 to sugars. And fixing co2 into calcium carbonate in scales covering their bodies. Aside from feeding on plankton, coral animals obtain nutrients from zooxanthellae, unicellular algae that live within their tissues. Stress (+1 degree celsius ) can induce ejection of the algae = bleaching. Symbiotic algae-farming is practiced by many water animals, like hydras and flatworms. May be cause by natural or human factors. Low salinity makes it easier to fight osmosis, less energy.
