Anthopleura elegantissima, Aggregating Anemone | ©Marlin Harms (North Point, Morro Strand State Beach, Morro Bay, California, US)

This colonial anemone with tentacles greenish to pinkish, can be found on rocky, tide swept shores along the Pacific coast of North America.

An interesting fact of these anemones, recently studied, is that High-intertidal individuals are exposed aerially up to 18 h each day, unlike low-intertidal individuals which may be continuously immersed over many days [read more].

Animalia - Cnidaria - Anthozoa - Hexacorallia - Actiniaria - Actiniidae - Anthopleura - A. elegantissima

"Giant Green Anemone" (Anthopleura xanthogrammica)

Also known as the Green Surf Anemone, Green Anemone, Solitary Anemone, Rough Anemone, and the Giant Tidepool Anemone, Anthopleura xanthogrammica is a species of Actiniid sea anemone that inhabits low to mid intertidal zones in the Pacific Ocean, ranging from Alaska to Southern California and rarely down to Panama. Like other sea anemones A. xanthogrammica sports several nemoatocyst lined tentacles which are used to paralyze and capture prey that wanders too close. Phoyosynthetic algae of the genus Zoochlorella and dinoflagellates of the genus Symbiodinium live in the tissue and gut of A. xanthogrammica, in this symbiotic relationship they will provide nutrients to the anemone via photosynthesis (partly giving the anemone its green coloration) and in turn they get a safe place to reside. 


Animalia-Cnidaria-Anthozoa-Hexacorallia-Actinaria-Nyantheae-Thenaria-Actiniidae-Anthopleura-A. xanthogrammica

Image: Stan Shebs

Beadlet anemone / ウメボシイソギンチャク

Actinia equina

The colony of Beadlet anemones. ウメボシイソギンチャクの群れ。

Animalia Cnidaria Anthozoa Actiniaria Actiniidae
動物界 刺胞動物門 花虫綱 イソギンチャク目 ウメボシイソギンチャク科

Photo taken at Tokyo Sea Life Park, Japan

A #RNA-seq approach to identify putative toxins from acrorhagi in aggressive and non-aggressive Anthopleura elegantissima polyps

Background: The use of venom in intraspecific aggression is uncommon and venom-transmitting structures specifically used for intraspecific competition are found in few lineages of venomous taxa. Next-generation transcriptome sequencing allows robust characterization of venom diversity and exploration of functionally unique tissues. Using a tissue-specific #RNA-seq approach, we investigate the venom composition and gene ontology diversity of acrorhagi, specialized structures used in intraspecific competition, in aggressive and non-aggressive polyps of the aggregating sea anemone Anthopleura elegantissima (Cnidaria: Anthozoa: Hexacorallia: Actiniaria: Actiniidae). Results: Collectively, we generated approximately 450,000 transcripts from acrorhagi of aggressive and non-aggressive polyps. For both transcriptomes we identified 65 candidate sea anemone toxin genes, representing phospholipase A2s, cytolysins, neurotoxins, and acrorhagins. When compared to previously characterized sea anemone toxin assemblages, each transcriptome revealed greater within-species sequence divergence across all toxin types. The transcriptome of the aggressive polyp had a higher abundance of type II voltage gated potassium channel toxins/Kunitz-type protease inhibitors and type II acrorhagins. Using toxin-like proteins from other venomous taxa, we also identified 612 candidate toxin-like transcripts with signaling regions, potentially unidentified secretory toxin-like proteins. Among these, metallopeptidases and cysteine rich (CRISP) candidate transcripts were in high abundance. Furthermore, our gene ontology analyses identified a high prevalence of genes associated with “blood coagulation” and “positive regulation of apoptosis”, as well as “nucleoside: sodium symporter activity” and “ion channel binding”. The resulting assemblage of expressed genes may represent synergistic proteins associated with toxins or proteins related to the morphology and behavior exhibited by the aggressive polyp. Conclusion: We implement a multifaceted approach to investigate the assemblage of expressed genes specifically within acrorhagi, specialized structures used only for intraspecific competition. By combining differential expression, phylogenetic, and gene ontology analyses, we identify several candidate toxins and other potentially important proteins in acrorhagi of A. elegantissima. Although not all of the toxins identified are used in intraspecific competition, our analysis highlights some candidates that may play a vital role in intraspecific competition. Our findings provide a framework for further investigation into components of venom used exclusively for intraspecific competition in acrorhagi-bearing sea anemones and potentially other venomous animals. #BMC

Starburst Anemone - Anthopleura sola

Anthopleura sola (Actiniaria - Actiniidae) is a solitary anemone up to 25 cm wide, with pale, variously colored tentacles with pink, lavender, or blue tips, arranged in five rings around the oral disk. 

The Starburst Anemone commonly lives on exposed rocky surfaces and in tidepools and crevices, in the middle intertidal zone of semiprotected rocky coastlines, and can be found in the Pacific Ocean, along the west coast of North America from Alaska to Baja California.

References: [1] - [2]

Photo credit: ©Douglass Moody | Locality: Royal Palms State Beach, San Pedro, California, US (2011)


Beadlet Anemone (Actinia equina)

…a species of sea anemone that can be found on the rocky coasts of the United Kingdom, Western Europe and the Mediterranean. This anemone is highly adapted to its environment and can thrive in high temperatures and dryness, some have even been found in areas with low salt. They also possess a ring of blue tentacles called acrorhagi which are used to fight off other anemones that attempt to invade their space.



Image Source(s)

Epiactis thompsoni

This striking anemone known by the scientific name of Epiactis thompsoni (Actiniaria - Actiniidae), lives in shallow waters of southern Australia and New Zealand.

Although the color pattern varies, they usually are red and pink. The column is smooth with vertical stripes of cream and red, and have about 40-60 short tentacles.

References: [1] - [2]

Photo credit: ©Saspotato | Locality: Portsea Pier, Melbourne, Victoria, Australia

Aggregating Anemone - Anthopleura elegantissima

Anthopleura elegantissima is a sea anemone which commonly lives on exposed rocky surfaces and in tidepools and crevices. It is found in the middle intertidal zone of semiprotected rocky coastlines of both the outer coast and bays, along the west coast of North America from Alaska to Baja California.

As its common name suggests, this species is found in clonal groups of aggregating individuals. Individuals range from 2-5 cm across the oral disc, but are usually less then 3.5 cm across. The disc can be twice that size when extended. Solitary animals are larger, averaging 6.5 cm across the oral disc; once considered a solitary form of the same species, these larger, non-cloning individulas have recently been described as a sibling species, Anthopleura sola

References: [1] - [2]

Photo credit: ©Richard Droker (CC BY-NC-ND 2.0) | Locality: Washington coast, US (2011)

Moonglow Anemone - Anthopleura artemisia

Also referred to as Buried Green Anemone, and Burrowing Anemone, Anthopleura artemisia (Actiniaria - Actiniidae) is a species often found buried in a mixed sandy, shelled, and cobbled ocean floor, with only its tentacles and oral disc exposed.

This anemone has long, slim tentacles. It varies in color from grayish green to brown or black, though sometimes it has pink or orange tentacles like the pictured specimen. These anemones are solitary, and can reach 10 cm in diameter with a buried column to 25 cm long. They can be found on shorelines along the west coast of North America, from Alaska to Baja California.

References: [1] - [2]

Photo credit: ©Marlin Harms | Locality: Montana de Oro State Park, San Luis Obispo Co., California, US (2010)


Spinnaker Anemone (Korsaranthus natalensis)

Also known as the candy-striped anemone, the spinnaker anemone is a species of Actiniid anemone which is endemic to the South African coast, where it occurs from False Bay to Durban. Spinnaker anemones are noted for being partly motile, as they use their parachute like disc to “sail” to different locations to prey on octocorals. 


Animalia-Cnidara-Anthozoa-Hexacorallia-Actiniaria-Actiniidae-Korasaranthus-K. natalensis

Image(s): Seascapeza


Brooding Sea Anemone (Epiactis prolifera)

Also known as the proliferating or small green anemone, the brooding sea anemone is a species of sea anemone endemic to the north-eastern Pacific. This species is unique as it is protogynic hermaphrodite, meaning it starts its life as a female and when it reaches a certain size it develops testes and lives as a proper hermaphrodite for the rest of its life. This species gets the name “brooding” as its young will remain within its mother’s gastrovacular cavity during early development. Like most cnidarians this anemone is a suspension feeder, disabling any prey that happens to stumble upon its tentacles.



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Beadlet anemone  (Tomate de mar)

Actinia equina (Actiniaria - Actiniidae), the Beadlet anemone, is a considerably versatile intertidal sea anemone, with a wide array of color variation, from green to red. The most common hue is rust-red.

In the beadlet anemone, the tentacles (up to 192) are arranged radially in six circles around the mouth (the opening to the gastrovascular cavity). Bright blue spots (shown in the photo), called acrorhagi, are below the tentacles on the outer margin of the column and look like warts.

This sea anemone is found primarily in the North Atlantic Ocean and the Mediterannean Sea, but populations also exist stretching down along Africa’s Atlantic coast.

Reference: [1]

Photo credit: ©Jeroen Zetz

Locality: Scherpenisse, Zeeland, Netherlands

Condylactis gigantea

A stunning close up of the so called Giant Caribbean anemone, Condy anemone, and Pink-tipped anemone, with a shrimp on it.

This beautiful anemones are scientifically named Condylactis gigantea (Actiniidae), and are commonly found in the Caribbean, most specifically the West Indies, and the western Atlantic, ranging from southern Florida through the Florida keys. They can be seen growing in lagoons or on inner reefs as either individuals or loose groups, but never as colonies.

The Condy anemone is approximately 15 cm high and 30 cm wide, making the disk diameter approximately 40 cm. They can exibit a variety of colors: white, light blue, pink, orange, pale red, or light brown. The mouth is surrounded by 100 or more tentacles, each long and tapered with pink-, scarlet-, blue- or green-ringed tips.

Reference: [1]

Photo credit: ©Courtney Platt

Locality: Grand Cayman

Crimson Anemone  (Snakelock anemone, Chevron-tentacle anemone, Fernald brooding anemone)

Macrophotography of Cribrinopsis fernaldi (Actiniaria - Actiniidae), a sea anemone from the North Pacific Ocean. commonly referred to as Crimson Anemone, although the overall color may be white, yellow, or pink.

These sea anemones up to 20 cm tall, have narrow zigzag lines, often red, across the tentacles. Tentacles are long and may droop down. It also has red lines radiating outward on the oral disk.

This anemone broods its young internally.

References: [1] - [2]

Photo credit: ©Conor McCracken

Locality: British Columbia, Canada

Dahlia Anemone | ©Ewan Anderson 

Urticina felina (Actiniaria - Actiniidae) photographed in the surging waters off of St. Abb’s Head at a site appropriately named, ‘Anemone Alley’, Scotland.

Urticina felina is commonly known as Northern red anemone or Dahlia anemone. It is a large anemone (base up to 15 cm diameter) with up to 160 short (up to 2 cm), stout tentacles arranged in multiples of ten. The coloration is very variable, ranging through white, yellow, orange, red, blue, grey, purple and brown being either plain or more commonly in some combination. Perhaps most commonly with a red column blotched with green/grey and a prominent pattern of red lines amongst the tentacle bases.