Stramonita haemastoma

Distribution

The red-mouthed rock shell occurs widely in tropical and warm water areas of the Western Atlantic Ocean. Regions where it can be found include the Caribbean Sea, North Carolina and Florida, Bermuda and the entire Brazilian coast, including the islands of Abrolhos and Fernando de Noronha. It is also found in the Eastern Atlantic: tropical Western Africa and Southwestern Africa, including Cape Verde and Angola, and in European waters, including Macaronesian Islands, the Mediterranean Sea and the southwest coast of Apulia. Its once abundant population in the Eastern Mediterranean collapsed early in the 21st century and had entirely disappeared by 2016.

Description

The adult shell size for this species varies between 22 mm and 120 mm.

Feeding habits

Stramonita haemastoma is a widespread gastropod that consumes bivalves, barnacles and limpets. In the Mediterranean Sea the whelk is an important predator of the bivalve Mytilaster minimus, but where the invasive Lessepsian migrant bivalve Brachidontes pharaonis is found, the whelk prefers to prey on that species over the native bivalves and barnacles. Through feeding behaviors such as attacking the margin or lip of shells where defenses are weakest, Stramonita haemastoma insert its proboscid between the valves injecting proteolytic enzymes and a toxin that causes bivalves to gape.

Human use

The shell was one of two principal sources of Tyrian purple, a highly prized dye used in classical times for the clothing of royalty, as recorded by Aristotle and Pliny the Elder.