Queen conchs are one of the largest herbivorous gastropods and graze on the dominant plants within the habitat in which they live (2). These plants are generally seagrasses, usually either turtle grass (Thalassia testudinum) or manatee grass (Cymodocea manatorum) (1). They ingest both the grasses composing their habitats and many algal species; including an unidentified blue-green, Cladophora sp., Hypnea cervicornius, and Polysiphonia sp (1). The animal uses its long, extendable proboscis to graze and to pick up rocks and stones, turning them over in order to remove the algae (1). S. gigas actively avoids eating predators; however, when ingesting algae off the substrate, they will often accidentally ingest small invertebrates and sand particles (1). Adults feed both day and night; whereas juveniles (< 8 cm) are found burrowed in the sand during the day and feeding only at night, a behavior commonly hypothesized as one of predator avoidance (1).
Watch the video below to see the conch using its long, muscular proboscis to graze on algae.
Queen conchs are under high predation pressures from numerous species in the Caribbean. Among these animals, the spotted eagle ray (Aetobatis narinari) and the loggerhead turtle (Caretta caretta) have been identified as the primary predators of the queen conch (1). Other species that are often found preying on conchs are as follows:
- Carnivorous gastropods: tulip snail (Fasciolaria tulipa), apple murex (Murex pomum)
- Various species of octopus
- Crustaceans: hermit crabs (various species), spiny lobster (Panulirus argus)
- Sharks and rays: tiger shark (Galeocerdo cuvieri), spotted eagle ray (Aetobatis narinari), southern stingray (Dasyatis americana)
- Various fishes: including but not limited to permit, hogfish, queen triggerfish, and porcupine fish
- Loggerhead turtle (Caretta caretta)
Many fish species that do not maintain the ability to break through the conch’s thick shell and operculum have also been observed feeding on the animal. These animals include various species of snapper, grouper, and grunt. It is believed that these fish prey upon S. gigas once the individual has died from other forces or has been discarded by some other predator (1).