Plantaginea Gorgonian, Muricea plantaginea

Plantaginea Gorgonian, Muricea plantaginea. Underwater photograph taken in the coastal waters off Isle Coronado, Baja California Sur, May 2023. Photograph courtesy of Dr. Tom Bartol, Carlsbad, California. Identification courtesy of Greg Timms, youtube.com/@CoralmasterdivesPuerto-Vallarta/videos.

Phylogeny:  The Plantaginea Gorgonian, Muricea plantaginea (Valenciennes, 1846), is a member of the Plexauridae Family of Gorgonians. The Muricea Genus is one of five genera in the Plexauridae Family and there are thirty-three species in the Muricea Genus. The species name plantaginea is a New Latin adjective meaning “resembling a plantain”. This refers to the flattened, fan-shaped, colony resembling the form of a plantain tree.

Morphology: Plantaginea Gorgonians grow as a flattened, fan-shaped, colony, which is attached to the substrate by a small holdfast. A main branch rises from the hold fast and then branches irregularly. The branches and branchlets grow laterally and branch repeatedly at 30° to 45° angles. The branches reach around 1.5 cm (0.6 inches) in diameter and the branchlets are closer to 5 mm. The longer, unbranched, terminal ends grow up to 15 cm (5.9 inches) in length. Large colonies reach 1.30 m (4 feet 3 inches) in height and 1.50 cm (4 feet 11 inches) in width, though most specimens are much smaller. The calyces (cups that surround the polyps) are ovate and up to 1.2 mm in length. There are from 8 to 22 calyces per square cm. Where the calyces are more crowded together, they become imbricate (overlapping like roof shingles). The polyps are connected by a thin coenenchyme. Colonies vary in color from brown to yellowish or whitish. The polyps are yellowish or white.

Habitat and Distribution: Plantaginea Gorgonians are found attached to rocks, coral, and other hard substrates. In some cases, the hard substrate is covered with sand or other sediment, often making for turbid water. They live at depths ranging from 3 m (10 feet) to 65 m (213 feet). Plantaginea Gorgonians are a subtropical to tropical Eastern Pacific species that are found in Mexican waters from San Carlos Bay, Sonora to Guatemala, including the Revillagigedo Islands. They have not been documented from the west coast of the Baja Peninsula.

Diet: The Plantaginea Gorgonian is a sessile suspension feeder that captures drifting food in the water column by individual polyps with small tentacles. These nutrients will reach all members of the colony through channels in the gastrovascular cavity. The Plantaginea Gorgonian’s diet consists of water-borne prey like micro plankton and suspended organic matter. They are an azooxanthellate coral.

Predation: Documentation of Plantaginea Gorgonian predators is very limited. Other similar species in the Muricea Genus are preyed upon by corallivorous fishes, gastropods and sea stars.

Reproduction: Plantaginea Gorgonian colonies are gonochoric (male or female for life). They can reproduce asexually through budding, and sexually through broadcast spawning. During spawning, mass amounts of eggs and sperm are released into the water and fuse into gametes. The gametes become planktonic planula larvae. These larvae will eventually settle on a substrate and begin to form a polyp. From here, a colony grows through budding. They can also reproduce asexually through fragmentation.

Ecosystem Interactions: Plantaginea Gorgonians is a poorly studied and documented species. Their commensal, mutualistic and parasitic relationships have not been formally documented. Other species in the Muricea Genus have microbial corallicolids living in their cells. It is thought that these corallicolids are parasitic, but they may be commensal. Many invertebrates species, such as amphipods, brittle stars, copepods, and polychaetes find shelter in the branches of Plantaginea Gorgonians.

Human Interactions: Plantaginea Gorgonians have a very limited impact on human activities. From a conservation perspective they have not been formally evaluated. Regional threats to the species include coastal development, water pollution, and increased sedimentation from coastal activities from human development.

Synonyms:  Eunicea tabogensis, Gorgonia plantaginea, Muricea appressa, Muricea appressa typica, Muricea appressa var. flavescens, and Muricea tenella.