Egregia menziesii

Endocladia muricata

Hesperophycus californicus

Pelvetiopsis limitata

Phyllospadix torreyi/P. scouleri

Postelsia palmaeformis

Silvetia compressa/S. deliquescens

Species Home



Egregia menziesii (Turner) Areschoug

(Includes entities previously assigned to Egregia laevigata Setchell)

Feather boa kelp

General Description (from Abbott and Hollenberg 1976 and Kendall et al. 2002):

Thick, flattened strap-like axes (each referred to as a rachis), with numerous small, lateral blades (can be flat, broad, narrow, filiform to cylindrical) and floats along the margin; thallus arises from dense hapterous holdfast, which can become fleshy and cone-like in large plants; thallus morphology approximately correlated with geographic distribution: northern populations (Alaska to Cape Mendicino) have tuberculate rachi, smooth sporophylls, and narrow, thick spatulate laterals (Blanchette et al. 2002); populations from Los Angeles to Baja California have smooth rachi, wrinkled sporophylls, and both broad, spatualte and narrow, filiform laterals; populations located in between have mixed and variable morphologies; southern California thalli initially produce spatulate laterals but then begin producing filiform laterals as they grow (Henkel 2003)

Smooth rachis; Tuberculated form

Habitat and Range (from Abbott and Hollenberg 1976):

Common on lower intertidal rocks in protected to moderately wave-exposed areas; midtidal to subtidal (20m); often mixed with Macrocystis at the inner edges of kelp beds; often found growing in mixed stands with Phyllospadix spp.; Alaska to Punta Eugenio, Baja California

Egregia with filiform laterals

Egregia with largely spatulate laterals

Egregia with the limpet Notoacmea insessa


Egregia is one of the most conspicuous algae in the intertidal zone. It provides shelter for many species of understory algae and invertebrates (Humphrey 1965). Notoacmea insessa is a limpet only found on Egregia, where it grazes on the rachis, producing oval scars or pits. This grazing activity can result in axis breakage and cause mortality in the kelp (Black 1974). Egregia is sensitive to desiccation and heat stress on the lowest midday tides (Engle and Davis 1996). Even when recruitment was continual, the 1982-83 El Niño Southern Oscillation caused high mortality (Gunhill 1985). Poor water quality might also affect Egregia. At a sewage outfall, Egregia was noticeably absent (Littler and Murray 1975). If recruitment is successful, recovery of Egregia populations can occur in as little as five months to 2 years due to fast growth rates (Murray and Littler 1979; Vesco and Gillard 1980).

Juvenile Egregia

Can be confused with: Juvenile Eisenia arborea, except juvenile Eisenia is corrugated on the blade surface, whereas Egregia is smooth (southern) or uncorrugated and tuberculate (northern)

Juvenile Eisenia arborea

Tuberculated, juvenile Egregia (northern)


Abbott IA and Hollenberg GJ (1976) Marine algae of California. Stanford Univ Press, Stanford, CA

Black R (1974) The biological interactions affecting intertidal populations of the kelp Egregia laevigata. Mar Biol 28: 189-98

Blanchette CA, Miner BG, Gaines SD (2002) Geographic variability in form, size, and survival of Egregia menziesii around Point Conception, California. Mar Ecol Prog Ser 239: 69-82

Gunnill FC (1980) Recruitment and standing stocks in populations of one green alga and five brown algae in the intertidal zone near La Jolla, California during 1973-1977. Mar Ecol Prog Ser 3: 231-43

Gunnill FC (1985) Population fluctuations of seven macroalgae in southern California during 1981-1983 including effects of severe storms and an El Niño. J Exp Mar Biol Ecol 85: 149-64

Engle JM, Davis GE (1996) Ecological condition and public use of the Cabrillo National Monument intertidal zone 1990-1995. Technical report. Cabrillo Historical Assoc, Cabrillo National Monument, Point Loma, CA

Henkel SK (2003) Reproduction and morphological variation in southern California populations of the lower intertidal kelp Egregia menziesii (O. Laminariales). M.S. Thesis, Cal State Univ, Fullerton

Humphrey AE (1965) The fauna of the seaweed Egregia laevigata at Santa Barbara, California. MA Thesis, Univ of California, Santa Barbara

Kendall A, Kusic K, Maloney E, Williams M (2002) List of species to be discussed at the 2002 MMS Taxonomic Workshop

Littler MM and Murray SN (1975) Impact of sewage on the distribution, abundance, and community structure of rocky intertidal macro-organisms. Mar Biol 30: 277-91

Vesco LL and Gillard R (1980) Recovery of benthic marine populations along the Pacific Coast of the United States following man-made and natural disturbances including pertinent life history information. U.S. Department of the Interior, Bureau of Land Management Service, POCS Reference Paper No. 53-4