M. pyrifera is the largest of all algae. The stage of the life cycle that is usually seen is the sporophyte, which is perennial and individuals persist for many years. Individuals may grow to up to 50 m (160 ft) long or more. The kelp often grows even longer than the distance from the bottom to the surface as it will grow in a diagonal direction due to the ocean current pushing against the kelp. The stalks arise from a holdfast and branch three or four times from near the base. Blades develop at irregular intervals along the stipe, with a single pneumatocyst (gas bladder) at the base of each blade. A related and similar-looking, but smaller species, M. integrifolia, grows to only to 6 m (20 ft) long. It is found on intertidal rocks or shallow subtidal rocks along the Pacific coast of North America (British Columbia to California) and South America. In New Zealand M. pyrifera is found on the in subtidal zone of southern North Island, the South Island, Chatham, Stewart, Bounty, Antipodes, Auckland and Campbell Islands. The species can be found on rock and on sheltered open coasts. Learn more about Giant Kelp