Carunculatum Feather Duster, Acromegalomma carunculatum
Carunculatum Feather Duster, Acromegalomma carunculatum. Underwater photo-graphs taken in Zihuatanejo Bay, Guerrero, March 2018. Photographs courtesy of Ron Woheau, Zihuatanejo. Identifications courtesy of Greg Timms, youtube.com/@Coral-masterdives-Puerto-Vallarta/videos.
Phylogeny: The Carunculatum Feather Duster, Acromegalomma carunculatum (Tovar-Hernández & Salazar-Vallejo, 2008), is a specialized species of marine polychaete tube worms and a member of the Sabellidae Family of Feather Duster Worms. The Acromegalomma Genus is one of forty-one genera in the Sabellidae Family, and there are fourty-two species in the Acromegalomma Genus. The Sabellidae Family is currently undergoing much needed taxonomic revision. Additionally, many species in the Sabellidae Family have been introduced to multiple locations, making range a less valuable tool in determining species identification. Positive identification of species in this family is difficult. As a result many identifications are stopped at at the genus level. The genus name Acromegalomma is a combination of Greek elements that means something like “big eye at end tips”. This refers to the compound eyes located at the tips of the radioles (crown tentacles). The species name carunculatum comes from the Latin word meaning “small, fleshy, outgrowths”. In this case, the outgrowth is a sensory organ called a caruncle.
Morphology: The Carunculatum Feather Duster has a well-developed crown of long filaments called radioles. The radioles circumscribe, and hide, the mouth. The crown neatly splits into two symmetric, semicircular lobes that unfold gracefully into an open horseshoe shape. Each feather has a white structural stripe at its center. Like other species in this genus, the tips of the radioles have dark, shiny, sub-spherical, compound eyes. These giant terminal eyes act like light meters to instantly detect moving shadows from nearby predators. Contrasting yellow patches below the eye-beads make them stand out intensely against the dark, iridescent blue-grey coloration of the rest of the plume. This species is named after its caruncle, a unique, sensory organ located dorsally between the dorsal lips. The caruncle features four ciliated bands that aid in sensory reception and feeding. The body consists of an anterior thorax and a posterior abdomen. The body is encased in a resilient leathery tube that is made out of mucus, sand, and shell fragments. The body can reach up to 16 cm (6.3 inches) in length. The protective tube can measure up to 1.3 cm (0.5 inches) in diameter. The radioles can be up to 2.2 cm (0.87 inches) in length.
Habitat and Distribution: Carunculatum Feather Dusters are a poorly researched and documented species. They are found attached to coral and possibly other hard substrates and soft substrates. There is no documentation of depth range for this species. The Carunculatum Feather Duster is an Eastern Pacific species. Documentation of their geographic range is limited. They are reported to be found in the Sea of Cortez, in the states of Baja California and Baja California Sur. They are also found along the Mexican mainland in the states of Guerrero and Oaxaca.
Diet: Carunculatum Feather Duster are suspension feeders, filtering plankton and organic matter from the passing currents, or by creating currents by use of the radioles.
Predators: Carunculatum Feather Duster predation is not documented. Other species in this family are preyed upon by fish (angelfish, butterflyfish, triggerfish, and wrasses) and shrimp.
Reproduction: The Carunculatum Feather Duster reproduced either asexually (through fragmentation) or sexually. Based on other species in this family, they may be either gonochoric (male or female for life) or sequential hermaphrodites (changing sex with age). Reproduction is sexual, through broadcast spawning, with external fertilization. The fertilized eggs drift as plankton before settling to the bottom as trochophore larvae, which then develop into adult worms.
Ecosystem Interactions: The Carunculatum Feather Duster is thought to be beneficial to coral reef habitats in that they help keep organic matter from smothering the coral animals. Otherwise, little is know about their relationship with other species.
Human Interactions: Carunculatum Feather Duster are utilized by the aquarium trade. From a conservation perspective the Carunculatum Feather Duster has not been formally evaluated.
Synonyms: Megalomma carunculata