Giant Kelp

Description:

Giant Kelp (or Macrocystis) has the distinction of being the largest marine plant (and seaweed) in the world; with the largest attached plant recorded being 65m long. The kelp plant has a root-like holdfast that fixes to rocky surfaces; a long slender stalk or stipe; and long, leaf-like blades or fronds, that are the major site of photosynthetic activity. The kelp plant is supported in the water by gas-filled bladders on each frond called pneumatocysts. The holdfast is cone-shaped and can grow up to 60 cm in diameter in large plants.

Habitat:

Located at the edge of the Catalina Casino building, the Casino Point Marine Park is Southern California's first city-designated underwater park. Established in 1965 by the City of Avalon as a reserve, Casino Point Marine Park has an abundance of marine life, giant kelp forests, and several shipwrecks to explore. Several artificial reefs have been established to provide additional habitats.

Notes:

Kelp forests harbor a greater variety and higher diversity of plants and animals than almost any other ocean community. Many organisms use the thick blades as a safe shelter for their young from predators or even rough storms. These dense canopies of algae generally occur in cold, nutrient-rich waters. Because of their dependency upon light for photosynthesis, kelp forests form in shallow open waters and are rarely found deeper than 15-40 meters (49-131 feet). Pieces of decomposing kelp (called detritus) can either sink to the depths of the ocean or get washed ashore, providing food for deep sea animals or intertidal marine life, respectively. Giant kelp has a multitude of inhabitants. Invertebrates graze on the blades, fish seek shelter in the dense forest and thousands of invertebrates live in the holdfast, such as brittle stars, sea stars, anemones, sponges and tunicates. Sea otters like to hunt in the kelp forest, where they find their favorite food and can wrap up in the kelp to keep from drifting away. Giant kelp is harvested as a source of algin, a binding agent used in the production of many foods and cosmetics, like ice cream, toothpaste and many cereals.