Nereocystis

genus of brown algae

Also known as: sea otter’s cabbage

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Last updated

July 1, 2026

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Nereocystis is a genus of brown algae, commonly known as bull kelps. These are annual seaweeds found primarily in deep waters and rapid tideways, capable of reaching lengths up to 40 meters (130 feet).1

The bull kelp has a tough, whiplike stalk that terminates in a large bladder. This bladder can contain up to 10% carbon monoxide and helps the plant stay afloat. The long, leafy outgrowths from the stalk are responsible for photosynthesis and reproduction. Historically, Nereocystis and other kelps were a source of potash and iodine.12

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kelp
Members of the genus Nereocystis, commonly called bull kelps, are annual kelps that grow primarily in deep waters and rapid tideways and can attain lengths up to 40 metres (130 feet). The stalk is tough and whiplike, terminating in a single large bladder containing up to 10 percent carbon…
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Members of the genus Nereocystis, commonly called bull kelps, are annual kelps that grow primarily in deep waters and rapid tideways and can attain lengths up to 40 metres (130 feet). The stalk is tough and whiplike, terminating in a single large bladder containing up to 10 percent carbon…
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seaweed
species of Macrocystis and Nereocystis of the Pacific and Antarctic regions exceed 33 metres (100 feet) in length. Laminaria, another kelp, is abundant along both the Pacific and Atlantic coasts. Gulfweed (Sargassum) is common as free-floating masses in the Gulf Stream and Sargasso Sea.
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species of Macrocystis and Nereocystis of the Pacific and Antarctic regions exceed 33 metres (100 feet) in length. Laminaria, another kelp, is abundant along both the Pacific and Atlantic coasts. Gulfweed (Sargassum) is common as free-floating masses in the Gulf Stream and Sargasso Sea.
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