Physical aspects: Light, depth, and chemistry of the open ocean

Microbes and plants : essential organisms in the open ocean

Sponges, cnidarians, and worms : animals of the ocean surface and seafloor

Mollusks, crustaceans, and echinoderms : advanced invertebrates of the open ocean

Fish : vertebrates in every region of the open ocean

Reptiles, birds, and mammals : rulers of the oceanic realm

The mysterious ocean.