Purple Gorgonian, Eugorgia rubens
Purple Gorgonian, Eugorgia rubens. Underwater photographs taken in Bahía de Banderas, Puerta Vallarta, Jalisco, September 2026 at dephts between 6 m (20 feet) and 9 m (30 feet). Photographs and identifications courtesy of Greg Timms, youtube.com/@CoralmasterdivesPuerto-Vallarta/videos.An excellent short video put together by Greg is avialable: https://www.youtube.com/watch?v=mL_v92mroxA&t=3s.
Phylogeny: The Purple Gorgonian, Eugorgia rubens (Verrill, 1868) is an octocoral and a member of the Gorgoniidae Family of Soft Corals. The Eugorgia Genus is one of thirteen genera in the Gorgoniidae Family, and there are seventeen species in the Eugorgia Genus. Breedy, Guzmán and Vargas (2009) conducted a comprehensive revision of Eugorgia using original type material together with recently collected and museum specimens. They recognized three principal species groups at that time, including the rubens-group, which consisted exclusively of Eugorgia rubens. The genus Eugorgia is restricted to the eastern Pacific and is characterized by the dominance of double-disc sclerites in the coenenchyme. Species are distinguished through a combination of colony growth form, branching pattern, polyp arrangement, coloration, and sclerite morphology rather than any single external character. The genus name Eugorgia comes from the Greek words meaning “good gorgons”. The gorgons were creatures with snake-like hair in Greek mythology. This refers to the snake-like appearance of these organisms. The species name rubens comes from the Latin word for “reddish”, “pink”, or “blushing”. In Mexico they are known as Gorgonia Morada.
Morphology: The Purple Gorgonian is characterized by its sparse colony architecture and distinctive single-row arrangement of polyp-mounds, and being a branching, tree-like, coral. The colonies are open and relatively sparse compared with the more bushy species of the genus. The main branches are slightly flattened, reaching approximately 4.7 mm (0.2 inches) in diameter, while the smaller branchlets are more rounded and 1.0 mm to 1.5 mm diameter. The branching is irregularly pinnate. Secondary branchlets arise laterally from the larger branches and are widely spaced, typically separated by 0.5 cm (0.2 inches) to 2.0 cm (0.8 inches). Branchlets may themselves rebranch, producing secondary branchlets. Unbranched terminal twigs are blunt and may reach 5.0 cm (2.0 inches) in length. There is a single longitudinal row of prominent polyp-mounds along each edge of the smaller branchlets. On the thicker branches the arrangement becomes more irregular. The polyps are fully retractile, and when retracted, they form pronounced mounds. The colony may be pink, purple, or bluish-purple color, with clear polyps. The colonies are attached to the substrate with a small holdfast. Purple Gorgonians reach a maximum of 60 cm (2 feet 0 inches) in height.
Habitat and Distribution: Purple Gorgonians are found attached to rocks and other hard substrates, often in shaded areas and areas subject to strong currents. They live from depths between 6 m (20 feet) to at least 70 m (230 feet). They are a subtropical to tropical Eastern Pacific species and have a large geographic range, reaching from Central California to Peru. The distribution data for this species in Mexican waters has been poorly documented. There are reports that they are found at various points along the west coast of the Baja Peninsula, and along the Mexican mainland coast. The above photos document the geographic distribution of Eugorgia rubens into Bahía de Banderas. The presence of the Purple Gorgonian in the Sea of Cortez has not been reported.
Diet: The Purple Gorgonian is an azooxanthellate nocturnal filter feeder with each retractile polyp being equipped with eight tentacles that are used to catch plankton and other types of organic matter found in the currents. Their open colony architecture provides extensive exposure of the feeding polyps to surrounding water while allowing water to move through the branching structure.
Predators: Purple Gorgonians are preyed upon by the Convoluted Arminia, Histiomena convolvula. Other possible predators include crustaceans, other mollusks, and fish.
Reproduction: Purple Gorgonians are gonochoric (male or female for life). They can reproduce asexually through budding and sexually through spawning. During spawning, mass amounts of eggs and sperm are released into the water and fuse into gametes. The larvae will eventually settle on a substrate and begin to form a polyp. Expansion of the colony occurs through cloning (asexual reproduction).
Ecosystem Interactions: Purple Gorgonian colonies provide three-dimensional habitat for numerous small marine organisms including brittle stars, crustaceans, the Green Ribbon Worm, mollusks, and polychaetes. As a suspension filter-feeder they contribute to the structural complexity of the rocky reef community.
Human Interactions: Purple Gorgonians have a very limited impact on human activities. The shallow-water habitat of Eugorgia rubens may increase its exposure to anthropogenic stressors associated with declining coastal water quality. Pollution, sedimentation, and nutrient enrichment from terrestrial runoff can promote the proliferation of algae and cyanobacteria, including filamentous forms that may become entrained within the branching structure of colonies. Accumulation of such growth may reduce water circulation around the colony and interfere with feeding, while persistent overgrowth has the potential to cause physical abrasion, smother living tissue, and contribute to tissue loss or colony decline. Similar effects associated with algal and cyanobacterial overgrowth have been documented in other gorgonian corals, suggesting that these interactions may represent a potential ecological stressor for the Purple Gorgonian. However, the prevalence, severity, and conservation implications of algal and cyanobacterial overgrowth in Eugorgia rubens has not been formally assessed.
Synonyms: None