Roostertail Conch Shell, Aliger gallus

Roostertail Conch, Aliger gallus. Shell collected offshore Bimini, Bahamas, April 2006. Size: 14.1 cm (5.5 inches) x 7.0 cm (2.75 inches). Collection, photograph and identification courtesy of Bob Hillis, Ivins, Utah.

Phylogeny:  The Roostertail Conch Shell, Aliger gallus (Linnaeus, 1758) is a gastropod mollusk in the Strombidae Family of True Conch Shells. The genus Aliger is one of thirty-one genera in this family, and there are only two species in this genus. They are also known as the Rooster-tail Conch.

Description: The Roostertail Conch Shell is a medium sized shell, consisting of seven to nine whorls. The shoulder of the whorls are marked by small knobs, except the body whorl shoulder is marked by large triangular knobs. The body whorl is marked by multiple low spiral ridges. The spire is of medium height and pointed. The aperture is long and the outer lip is flared and extends, as a narrow fold, well beyond the spire. This is the only conch species to have this narrow extension above the spire.  The anterior canal is short and open. The exterior is mottled brown, yellow, and white. The interior is peach to orange, giving way to white further in. Roostertail Conchs reach a maximum of 20 cm (7.9 inches) in length.

Habitat and Distribution:  Roostertail Conchs are found on sand and rubble. They live as shallow as 300 cm (1.0 foot), and as deep as 82 m (269 feet). Some sources extend the maximum depth to 110 m ( 360 feet). They are a tropical Western Atlantic Ocean species and in Mexican waters they are primarily found in the Caribbean species, ranging from Progreso, Yucatán, to Belize.

Ecology and Behavior: Roostertail Conchs are grazers that feed primarily on algae. They are prey for crabs, octopuses, and fish. They are gonochoric and reproduce sexually, with internal fertilization. The eggs are laid in sticky, string-like masses. There is no mention in the available literature of them engaging in any types of commensal, parasitic, or symbiotic relationships. Roostertail Conchs have historically been collected by artisanal fisheries and by shell collectors, which has impacted localized populations.  From a conservation perspective they have not been formally evaluated. They are somewhat uncommon, and though they have a relatively wide distribution they should be a species to be considered to be  of Concern.

Synonyms: Lambis velum, Lobatus gallus, Strombus gallus, and Strombis solitaris.