Phytoplankton are simple plants that live in the surface zone of the ocean, acting as the first link in the ocean's food chain.
(Phytoplankton; are; simple plants that live in the surface zone of the ocean,) (simple plants; live; L:in the surface zone of the ocean)
Phytoplankton simple plants
are live
simple plants that live in the surface zone of the ocean,
L:in the surface zone of the ocean