Macrocystis, more commonly known as giant kelp, resides in the Pacific Ocean off the coast of North America from Canada to Baja California. Giant kelp begins life as a microscopic spore but can grow up to 200 feet in length with its upper fronds forming a dense canopy at the ocean surface. Giant kelp gravitates towards depths of less than 120 feet with temperatures less than 72 degrees Farenheit. It is anchored to the rocky bottom of the ocean by a holdfast. Giant kelp is harvested and used in such products as toothpaste, ice cream, and cereals.
Laminaria, also known as Japanese kelp or Kombu, is native to the Pacific waters off the coasts of Japan. However, the invasive species can now be found throughout the coasts of China and North America. Japanese kelp grows to about 30 feet in height and provides a dense canopy, which is home to many invertebrates and hatchlings. It is commonly used as a flavoring agent in Japanese cuisine.
Nereocystis luetkeana, or bull kelp, resides in the same geographic locales as giant kelp. It can grow upwards of 70 feet in height, and typically resides in shallower water than giant kelp. The kelp is edible, but is not as extensively harvested as either giant or Japanese kelp. Unlike giant kelp, bull kelp is an annual plant, meaning it has a life cycle determined by a growing season.
Ecklonia, a genus of kelp, is composed of nine different species. The Ecklonia genus can be found in all the world's oceans in typically shallow waters of a depth 10 feet or less with an average maximum height of 12 feet. Species of kelp in the Ecklonia genus typically serve as herbal remedies in Asian cultures and as food supplements worldwide.
Egregia comprises a genus of kelp. There are several species within the genus. Egregia species generally reside in lower intertidal to subtidal zones of about 15 feet in depth with heavy wave action. The various species average about 20 feet for maximum height. The species in the genus are edible but not as prominent nor as commercially sought after as the aforementioned kelp genuses and species.