<P> A wide range of sea life uses kelp forests for protection or food, including fish, particularly rockfish, and many invertebrates, such as amphipods, shrimp, marine snails, bristle worms, and brittle stars . Many marine mammals and birds are also found, including seals, sea lions, whales, sea otters, gulls, terns, snowy egrets, great blue herons, and cormorants, as well as some shore birds . </P> <P> Frequently considered an ecosystem engineer, kelp provides a physical substrate and habitat for kelp forest communities . In algae (kingdom Protista), the body of an individual organism is known as a thallus rather than as a plant (kingdom Plantae). The morphological structure of a kelp thallus is defined by three basic structural units: </P> <Dl> <Dd> <Ul> <Li> The holdfast is a root - like mass that anchors the thallus to the sea floor, though unlike true roots it is not responsible for absorbing and delivering nutrients to the rest of the thallus . </Li> <Li> The stipe is analogous to a plant stalk, extending vertically from the holdfast and providing a support framework for other morphological features . </Li> <Li> The fronds are leaf - or blade - like attachments extending from the stipe, sometimes along its full length, and are the sites of nutrient uptake and photosynthetic activity . </Li> </Ul> </Dd> </Dl> <Dd> <Ul> <Li> The holdfast is a root - like mass that anchors the thallus to the sea floor, though unlike true roots it is not responsible for absorbing and delivering nutrients to the rest of the thallus . </Li> <Li> The stipe is analogous to a plant stalk, extending vertically from the holdfast and providing a support framework for other morphological features . </Li> <Li> The fronds are leaf - or blade - like attachments extending from the stipe, sometimes along its full length, and are the sites of nutrient uptake and photosynthetic activity . </Li> </Ul> </Dd>

What kind of algae form the giant kelp forests off the coast of california