Shell massive, solid, of 6-7 whorls with a peripheral keel. Sculpture of unequal spiral cords, alternating stronger and weaker, and of axial folds; the intersection of the axial folds with the spirals forms nodose knobs, of which those along the keel are most developed. Aperture relatively small, with thick outer lip, denticulate inside, and a shallow, broadly open siphonal canal.
whitish to tan with the cords stained with brown on the nodes of peripheral keel and body whorl spirals. Aperture cream or yellowish inside.
common size :
up to 25 mm in the Red Sea; Mediterranean specimens 18 mm.
This species resembles native species of the genus Pollia, in general shape and in having dark stains on the knobs. Species of Pollia have more rounded whorls, not definitely keeled; a well-defined anal canal in the aperture, opposite to the siphonal canal, delimited by a denticle which is hardly expressed in Ergalatax. Also, Pollia usually has a whitish spiral zone on the middle of the body whorl. Other look-alike species of Ergalatax in the Indian Ocean are discussed by Houart (1996), to whom we refer.
BIOLOGY / ECOLOGY
Larvae are planktotrophic, ensuring long-distance dispersal.