Since the giant kelp is not a plant, it does not have roots. Instead, it obtains all of the necessary nutrients directly from the water and is attached to the rocky bottom by a structure known as a holdfast. Like plants, however, the giant kelp harvests the sun’s energy through photosynthesis and does not feed on other organisms.
This species is one of the fastest growing species in the world, and under perfect conditions, it has been known to grow up to two feet (60 cm) in a single day.
Once and individual giant kelp reaches the sea surface, it continues to grow horizontally, floating in large mats that shade the water column and sea floor below. In order to remain upright, each giant kelp blade (leaf) includes a gas-filled pod that floats.
Several individuals growing together can create dense forests that are an important ecosystem in temperate, coastal areas where they live. Several species eat giant kelp, and fluctuating populations of purple sea urchins are known to play a role in kelp forest formation and destruction. Several species of sharks, bony fishes, lobsters, squids, and other invertebrates are known to live in or near kelp forests.