Life in the Open Ocean
G5 U6 OVR GRADE 5 UNIT 6 OVERVIEW Life in the Open Ocean Introduction Open ocean ecosystems are complex, self-sustaining, and interdependent communities of marine plants, bacteria, and animals. Commercial and recreational fi shing and tourism are prime benefi ciaries of open ocean ecosystems. Because this unit addresses complex interrelationships in open ocean ecosystems, students are initially made aware of the global importance of open oceans. Unlike the continents, which are surrounded by submerged continental shelves, the Hawaiian Islands were formed by volcanic lava fl ows that rose directly from the bottom of the ocean. Due to this, the nearshore shallow water areas surrounding the islands are very narrow and the deeper open ocean waters are much closer to land than their continental counterparts. Students study these nearshore and open ocean areas by exploring marine maps of the Hawaiian Islands. Students gain a better understanding of ecosystems by identifying plankton and its role in these ecosystems. They discover that phytoplankton are at the base of food chains and food webs in marine ecosystems. Students understand that phytoplankton are eaten by zooplankton (herbivores and fi rst-level consumers), which are eaten by small organisms, which, are in turn, eaten by larger organisms, such as sharks further up the food chain. Using Internet resources, students identify and list the islands’ most common types of sharks, recording relevant statistics prior to developing nearshore and open ocean energy pyramids. Students also note which animals are producers, consumers, or decomposers. Not much goes to waste in open ocean ecosystems. Students fi nd that marine snow (excess organic materials, including dead animals, plants, sediments, and fecal matter) aggregate and sink toward the dark ocean bottom where food is scarce.
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