Plants and Algae
There are only a few true plants in the oceans; these include salt marsh grasses and mangrove
trees. But large algae, or seaweed, also use photosynthesis to make food, just as plants do
on land. These organisms have to live in the photic zone, because they require sunlight for
photosynthesis. For that reason, most plants, seaweeds and algae in the ocean are found
near the ocean surface or close to the shore. The large algaekelpgrows in the neritic zone
(Figure14.29). Kelp tends to grow in forests, and can reach over 50 meters long. Kelp
forests sustain an abundance of life, like the otter that lives in their swaying stems. It is
thought that land plants adapted from ocean organisms some 500 million years ago.
Figure 14.29: Kelp is common off the shores of California. Kelp is a crucial organism in
many food webs near the coast. ( 12 )