Anthopleura xanthogrammica

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Anthopleura xanthogrammica
Scientific classification
Kingdom: Animalia
Phylum: Cnidaria
Class: Anthozoa
Subclass: Hexacorallia
Order: Actiniaria
Suborder: Nyantheae
Infraorder: Thenaria
Family: Actiniidae
Genus: Anthopleura
Duchassaing de Fonbressin & Michelotti, 1860
Species: Anthopleura xanthogrammica

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Anthopleura xanthogrammica, or the Giant Green Anemone, is a species of intertidal anemones, of the family Actiniidae.

Other common names: Green Surf Anemone, Giant Green Sea anemone, Green Anemone, Giant Tidepool Anemone, Solitary Anemone, and Rough Anemone [1]


Physical Description

The column width and height can reach a maximum of 17.5 [2] and 30 cm, respectively.[3] The crown of tentacles can be as wide as 25 cm in diameter,[3]while the column, itself, tends to be widest at the base in order to offer a more stable connection to the rocks.[4]

It has a broad, flat oral disk surface [5] and no striping, banding, or other markings [4]


If A. xanthogrammica is exposed to proper amounts of sunlight, it can appear bright green[4] when submerged under water.

When not submerged, it appears dark green or brown. This is because the anemone tends to close up and "droop" and its now exposed column is actually dark green and slightly brown, but hidden tentacles and oral disk are bright green.[2]


The tentacles, which are short and conical,[2] are arranged in six or more rows surrounding the oral disk[3] [6] and can be pointed or blunt at the tips.[4]


Generally, A. xanthogrammica is found along the low to mid intertidal zones of the Pacific Ocean, from Alaska to Southern California and sometimes downwards to Panama, where cold water swells can occur.[3] [4] [6] [7]


Sandy or rocky shorelines, where water remains for most of the day, are the most suitable habitat for A. xanthogrammica.[3] They can generally be found in tide pools that are no deeper than 30 m. [2] Occassionally A. xanthogrammica can be found in deep channels of more exposed rocky shores and concrete pilings in bays and harbors. [4]

Biology and Natural History

Photosynthetic algae, zoochlorellae, and the dinoflagellates, zooxanthellae, live in epidermis and tissue of the gut of A. xanthogrammica forming a symbiotic relationship. This relationship ca provide nutrients to the anemone via photosynthesis and contribute to the bright green color of the oral disk and tentacles. [3] [6] The bright green color is also due to pigmentation.[4]

Anthopleura xanthogrammica anemones living in caves and shady zones have reduced or no natural symbionts and tend to be less colorful. [3] [6] [4] [2]


These anemones tend to live a solitary life, with no more than 14 individuals per square meter. [3][6][4] They can move slowly using their basal disks, but usually stay sessile.[3][6] Like other anemones, A. xanthogrammica can use stinging cells located in the tentacles as protection from predators and a mechanism to capture prey. [3][6]


Anthopleura xanthogrammica reproduce sexually via external fertilization of sperm and eggs in the late fall. Newly formed pelagic, planktotrophic larvae float in the water until dispersing and settling in mussel beds.[3][6][2]


Nematocysts (stinging cells)found in the tentacles assist A. xanthogrammica to catch and paralyze prey. [3][6][2] After feeding and digestion is complete,the anemone excretes its waste back through the mouth opening. [3][6]

Predators and Prey

Main predators of A. xanthogrammica include: the seastar Dermasterias imbricata[4], the nudibranch Aeolidia papillosa and the snail Epitonium tinctum (both feed on the tentacles), and the snails Opalia chacei and Opalia funiculata and the sea spider Pycnogonum stearnsi (that feed on the column)[3] [6]

The anemone feeds on sea urchins, small fish, and crabs, but detached mussels seem to be the main food source.[4][6]

Similar Species

Occasionally, A. xanthogrammica can be confused with a large A. elegantissima or an A. sola but both have pink-tipped tentacles and a striped oral disk, unlike A.xanthogrammica.[4]

Other Anthopleura Species

A. artemisia[1] [5]

A. elegantissima[1] [5]

A. sola[8]

A. aureoradiata [8]


  1. 1.0 1.1 1.2 Lamb, A and B Handy. 2005. Marine Life of the Pacific Northwest. Harbour Publishing, British Columbia: 85.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Laroche, C. 2005. Anthopleura xanthogrammica (on-line), Race Accessed May 10, 2010 at
  3. 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 3.13 Skiles, M. 2001. Anthopleura xanthogrammica (On-line), Animal Diversity Web. Accessed May 11, 2010 at
  4. 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 White, B. 2004. Anthopleura xanthogrammica (on-line), Walla Walla University. Accessed May 10, 2010 at
  5. 5.0 5.1 5.2 Kozloff, E. 1973. Seashore Life of the Northern Pacific Coast. University of Washington Press, Seattle, 166-167.
  6. 6.00 6.01 6.02 6.03 6.04 6.05 6.06 6.07 6.08 6.09 6.10 6.11 Encyclopedia of Life. 2010. “Anthopleura xanthogrammica” (on-line), Accessed May 10, 2010 at
  7. Gotshall, D. 2005. Guide to Marine Invertebrates. Shoreline Press, Santa Barbara:30.
  8. 8.0 8.1 Wikipedia. 2010. Anthopleura (on-line), Accessed May 11, 2010 at