Introduction to Marine Biology 3rd Edition by George Karleskint, Richard Turner, James Small

Exercise 2

Although less diverse and abundant than in coastal waters, life in the open sea is remarkably diverse. Viruses, bacteria, and archaeons live there and play important roles in food webs and biogeochemical cycles. Eukaryotic phytoplankton primarily are microbes, but sargassum weeds are notable among the megaphytoplankton. Zooplankton include many kinds of microbes, but larvae of fish and several kinds of adult cnidarians, molluscs, and urochordates occur in the open sea. Nekton specialized for open-ocean life include billfish, sharks, yellow-bellied sea snake, leatherback sea turtle, penguins, and many species of whale.