Stretched Mesh Sea Fan, Pacifigorgia stenobrochis
Stretched Mesh Sea Fan, Pacifigorgia stenobrochis. Underwater photograph taken in Bahía de Banderas, Puerta Vallarta, Jalisco, October 2026. Photograph and identification courtesy of Greg Timms, youtube.com/@CoralmasterdivesPuerto-Vallarta/videos.
Phylogeny: The Stretched Mesh Sea Fan, Pacifigorgia stenobrochis (Valenciennes, 1846), is an octocoral within the Gorgoniidae Family of Soft Corals. The Pacifigorgia Genus is one of thirteen genera in the Gorgoniidae Family, and there are thirty-seven species in the Pacifigorgia Genus. Monographic revisions by Breedy & Guzman (2002) further established this species as valid and stable. The species name stenobrochis comes from two Greek components: steno-meaning tight or narrow, and brochis – meaning mesh, net, or loop. This name refers to the narrow, elongated, mesh of these corals.
Morphology: Stretched Mesh Sea Fans are colonial organisms, with polyps that have 8-fold radial symmetry. Their eight tentacles are pinnate (having a feather-like appearance). The polyps have a flower-like appearance, a hollow digestive cavity, and specialized stinging structures in tentacles surrounding the mouth. As octocorals, they have tiny spine-like hard parts in their bodies called sclerites (or spicules) that give them some degree of support. The branches have a central core, which is made of a horn-like substance called gorgonin. Gorgonin is a protein which is exclusive to the gorgonians and which contains significant amounts of iodine and bromine. The sclerites are located in the solid core. The polyps are embedded in a gelatinous material (called the coenenchyme) which surrounds the core. The material surrounding the openings in the coenenchymes (from which the polyps emerge) are called calyces (singular calyx). The branches are arranged in a fan-shaped plane. Stretched Mesh Sea Fans form large colonies, reaching 20 cm (7.9 inches) in height and 58 cm (23 inches) in width.
Colony Architecture: Stretched Mesh Sea Fan colonies may exist as a single fan or be subdivided into 2 to lateral fans. The stem is very short or absent, and the holdfast is wide and strong.
Mesh Metrics: Stretched Mesh Sea Fans have long oblong, or rectangular, meshes that reach 1.0 cm to 5.0 cm by 1 mm to 4 mm in size (2 meshes/cm²). The individual branches are round in cross-section and average 2.0 mm to 5.0 mm in diameter. This species lacks the midribs of many other sea fans.
Polyps and Calyces: The Stretched Mesh Sea Fans has polyps that are distributed in longitudinal rows along both sides of the branches. The polyps are widely distributed, giving the branch a smooth texture. The coenenchymal rings are oval. The polyps reach 1.5 mm in diameter.
Coloration Profiles: Stretched Mesh Sea Fans vary in color from deep pink, reddish-purple, dark yellow, to brown, sometimes intermingled with orange. The polyps are orange.
Field Identification Key: The elongated oval, or rectangular, mesh of Stretched Mesh Sea Fans distinguish them from the symmetrical, circular, or multi-sided honeycomb patterns that characterize the vast majority of Eastern Pacific Pacifigorgia colonies. The loosely flowing grid of this species forms distinctly large vertical slots and the branches are fairly flexible.
Habitat and Distribution: Stretched Mesh Sea Fans are found firmly attached to on rocky reefs, deep walls, vertical walls and volcanic shelvess. They typically reside at depths between 3 m (10 feet) to 30 m (100 feet). They are a tropical Eastern Pacific species with a discontinuous distribution in the Mexican waters of the Pacific being found in the southern Sea of Cortez south od Loreto, Baja California Sur and San Carlos Bay, Sonora. They are especially abundant in the Cabo Pulmo region. They are also found along the mainland coast in the coastal waters of Guerrero and Oaxaca.
Diet: Stretched Mesh Sea Fans are azooxanthellate suspension feeders. The tiny octocoral polyps rely entirely on moving water currents to deliver micro-zooplankton (such as copepods and microscopic invertebrate larvae), phytoplankton, and organic particulate matter (marine snow). They lacks the polyp size and stinging capability to consume macro-organisms like amphipods or fish larvae.
Predators: Predation studies specific to Stretched Mesh Sea Fans are poorly documented. Their tissue is subject to opportunistic, localized grazing by browsing omnivorous reef fish and specialized Panamic corallivores, including ovulid gastropods, and specialized nudibranchs.
Reproduction: Stretched Mesh Sea Fans are gonochoric (male or female for life) and reproduce sexually through synchronized broadcast spawning events. External fertilization produces a free-swimming, planktonic planula larval stage before settlement. They also reproduce asexually through continuous tissue budding to expand the fan network, and fragmentation recovery.
Ecosystem Interactions: Stretched Mesh Sea Fans create a benthic microhabitat sanctuary. It acts as a effective current baffle, hosting an expansive community of associated micro-crustaceans, caprellid amphipods, specialized microbial biofilms, brittle stars, symbiotic copepods, and commensal shrimp.
Human Interactions: The Stretched Mesh Sea Fans has a limited direct human interaction. From a conservation perspective, they have not been formally evaluated.
Synonyms: Gorgonia (Eugorgia) stenobrochis, Gorgonia stenobrochis, Gorgonia stenobrochis typica, Leptogorgia stenobrochis, Litigorgia stenobrochis, and Rhipidigorgia stenobrachis.