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Nereocystis luetkeana at Caspar Point, California
Nereocystis luetkeana at Caspar Point, California
Scientific classification edit
Kingdom: Chromista
Phylum: Gyrista
Subphylum: Ochrophytina
Class: Phaeophyceae
Order: Laminariales
Family: Laminariaceae
Genus: Nereocystis
Postels & Ruprecht
N. luetkeana
Binomial name
Nereocystis luetkeana
(K.Mertens) Postels & Ruprecht

Nereocystis (Greek, 'mermaid's bladder') is a monotypic genus of subtidal kelp containing the species Nereocystis luetkeana.[1] Some English names include edible kelp, bull kelp, bullwhip kelp, ribbon kelp, bladder wrack, and variations of these names.[2] Due to the English name, bull kelp can be confused with southern bull kelps, which are found in the Southern Hemisphere.[3][4] Nereocystis luetkeana forms thick beds on subtidal rocks, and is an important part of kelp forests.


The species Nereocystis luetkeana was named (as Fucus luetkeanus) after the German-Russian explorer Fyodor Petrovich Litke (also spelled Lütke) by Mertens. The species was renamed in a description by Postels and Ruprecht.[5]


Bull kelp near Cambria, California. Top of stipe, pneumatocyst and blades shown on this freshly washed-ashore specimen. Also note nearby fragments of Macrocystis on this gray sand beach. October 2017 photo.

Individuals can grow to a maximum of 36 m (118 ft).[6] Nereocystis has a holdfast of about 40 cm (16 in), and a single stipe, topped with a pneumatocyst containing carbon monoxide, from which sprout the numerous (about 30-64) blades. The blades may be up to 4 m (13 ft) long, and up to 15 cm (5.9 in) wide. It is usually annual, sometimes persisting up to 18 months. Nereocystis is the only kelp which will drop spore patches, so that the right concentration of spores lands near the parent's holdfast.

The thallus of this common canopy-forming kelp has a richly branched holdfast (haptera) and a cylindrical stipe 10–36 m (33–118 ft) long, terminating in a single, gas-filled pneumatocyst from which the many blades, up to 10 m (33 ft) long, develop. Blade growth can reach 15 cm (5.9 in) per day. Reproductive patches (sori) develop on the blades and drop to the seafloor at maturity.


The species is common along the Pacific Coast of North America, from Southern California to the Aleutian Islands, Alaska. However, drift individuals disperse with ocean currents further south into northwest Baja California, Mexico.

This annual kelp grows on rock from the low intertidal to subtidal zones; it prefers semi-exposed habitats or high-current areas. Offshore beds can persist for one to many years, usually in deeper water than Eualaria or Macrocystis, where they co-occur.


  1. ^ Fisher, K; Martone, P.T. (April 2014). "Field Study of Growth and Calcification Rates of Three Species of Articulated Coralline Algae in British Columbia, Canada". Biological Bulletin. 226 (2): 121–130. doi:10.1086/bblv226n2p121. PMID 24797094. S2CID 20391876.
  2. ^ Angier, Bradford (1978). Field Guide to Medicinal Wild Plants. Harrisburg, Pa.: Stackpole Books. p. 156. ISBN 978-0-8117-2076-2.
  3. ^ Cheshire, A.C.; Hallam, N. (2009). "Morphological Differences in the Southern Bull-Kelp (Durvillaea potatorum) throughout South-Eastern Australia". Botanica Marina. 32 (3): 191–198. doi:10.1515/botm.1989.32.3.191. S2CID 83670142.
  4. ^ Fraser, C.I.; Winter, D.J.; Spencer, H.G.; Waters, J.M. (2010). "Multigene phylogeny of the southern bull-kelp genus Durvillaea (Phaeophyceae: Fucales)". Molecular Phylogenetics and Evolution. 57 (3): 1301–11. doi:10.1016/j.ympev.2010.10.011. PMID 20971197.
  5. ^ Abbott, Isabella A.; Isabella, Abbott; Hollenberg, George J. (1 August 1992). Marine Algae of California. Science. Vol. 101. pp. 188–92. Bibcode:1945Sci...101..188S. doi:10.1126/science.101.2617.188. ISBN 9780804721523. PMID 17750419. Retrieved 22 February 2018 – via Google Books.
  6. ^ "Nereocystis". Archived from the original on 2010-05-31. Retrieved 2013-08-05.

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