Which term describes organisms that drift or float in the water column and form the base of many aquatic food webs?

• A. Plankton
• B. Neritic zone
• C. Benthos
• D. Pelagic

Answer: (A)

Plankton are organisms that drift or float in the water column and form the base of many aquatic food webs. Because they are carried by currents and cannot reliably swim against them, they stay suspended in the open water, where they capture energy from sunlight (in the case of phytoplankton) or feed on other tiny organisms (in the case of zooplankton). Phytoplankton are the primary producers, turning sunlight into organic matter, and zooplankton transfer that energy up the food chain as they consume phytoplankton and are then eaten by larger aquatic organisms. The label pelagic refers to the open-water habitat these organisms occupy, but the defining trait here is their drifting, floating lifestyle. Benthos describes organisms living on the seabed, not in the water column, and the neritic zone is a coastal geographic region, not a biological category of drifting organisms.