Floating in the open sea rather than living on the seafloor.(adjective)
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Use "planktonic" in a sentence
"Bacteria that grow in biofilm communities can be as much as 10,000 times more resistant to antibiotics than the so-called planktonic bacteria, which circulate around the body as individual cells."
"With funding from the Australian Government Department of Climate Change, Howard and his colleagues collected microscopic marine animals - called planktonic foraminifera, or forams - from the South Tasman Rise region of the Southern Ocean."
"Change, Howard and his colleagues collected microscopic marine animals - called planktonic foraminifera, or forams - from the"