Marine Wildlife Encyclopedia
Queen Conch Strombus gigas
Species ID: S.SGb
Description: Possesses a large conical shell with a flared lip which spirals to a point adorned with knobby spines. The orange to brown shell is often covered in encrusting algae, while the inside edge of the lip is a rich pink or orange colour. Small yellow eyes on stalks protrude from under the narrow end of the shell, and a yellowish horn on the end of the muscular foot is used for locomotion.
Maximum size: 30cm (12 in), the largest marine snail
Longevity: Up to 30 years
Status: Not currently on the IUCN endangered species list due to a lack of information, but its trade is restricted by CITES
Queen Conch & People: The queen conch is highly sought after for food in the Caribbean and has become scarce in many areas due to overharvesting, although new mariculture initiatives are now helping to provide a stable supply of farmed queen conchs
Geographical Range: Common to occasional throughout the Caribbean
Coral Reef Zone: Queen conchs are commonly found in sand or rubble areas of the shore zone, back reef, fore reef zones, particularly in seagrass meadows
Favourite Habitat: Adult queen conchs are found in deeper patch-reef areas, whereas juveniles are more common in shallow seagrass beds
Depth Range: 1 – 30 m (3 – 100 ft)
A Day in the Life
Dawn: Activity declines and conchs seek shelter
Day: Queen conchs are less active and often hide under ledges or within caves on the reef. Mating may also occur during the day
Dusk: Queen conchs leave their shelter to graze
Night: Queen conchs graze in sandy areas throughout the reef; mating may also occur
Who Eats Who?
The queen conch is primarily a herbivore and grazes algae and sometimes detritus (decaying plants and animals). Juveniles are eaten by a variety of fish, but the adult’s imposing shell deters most predators. Adults are only eaten regularly by predators specialized in feeding on hard-shelled prey such as the nurse shark, spotted eagle ray and stingrays.
Scuba Diver & Snorkeler Best Practices
Practice snorkeling skills away from the reef, such as near the beach or in a sandy area. Relax in the water, and try to swim without using your arms. Remember, practice makes perfect.
The queen conch is slow moving and easily found by divers and snorkelers that follow the wavy trails they leave behind in the sand. Though the animal may initially withdraw into its shell when approached, it soon resumes normal activities if left undisturbed.
Queen conchs are active herbivores that graze in sand and rubbleareas, particularly where seagrass is found. Conchs feed on the algae and bacteria that grow on seagrasses, and may also eat sand and rubble in order to remove the algae growing on them. They are mainly active at night but some may also graze for short periods during the day.
Observe, record & share:
O S.SGb-101 – Grazing: Conchs move across the seafloor scraping algae off sand and rocks and seagrass, sometimes leaving a trail of grazed ground behind them
Attack & Defense Behaviour
Young queen conchs have relatively thin shells and are vulnerable to a wide variety of predators, which is why they rely on several defensive behaviours in addition to their shell. Very young queen conchs often burrow under the sand to hide from predators, and may be found partially buried or appear as lumps in the sand. Young conchs may also crowd together, making individuals harder to flip over and consume. Adults are afforded better protection by their larger size and thicker shell. At the first sign of danger, conchs retract into their shell. If seized by a predator, they use a claw on the end of their foot to pry themselves loose, and if flipped they can use this same claw to right themselves.
Observe, record & share:
O S.SGb-201 – Burrowing: Very young conchs burrow under the sand to hide from predators, and can sometimes be seen protruding from the bottom of seagrass beds
OS.SGb-202 – Retraction: The conch retracts exposed body parts into the shell to protect itself
O S.SGb-203 – Righting: A conch flipped over by a predator uses its claw to right itself
O S.SGb-204 – Aggregation: Young conchs crowd close together to reduce predation, as crowding makes each individual conch harder to flip over
O S.SGb-205 – Prying: A conch will use its claw to try to and pry itself away from a predator if seized
Queen conchs reproduce sexually and do not change sex during reproductive development. During the breeding season, conchs move to the deeper part of their range and seek members of the opposite sex. Males approach females from behind. As the narrow end of the male’s shell connects with the wide end of the female, the male xtends a dark, tube-like organ under the female’s shell and transfers his sperm. Females can store sperm for weeks; they fertilize their eggs when they are ready and lay them in sandy areas. The egg mass they lay resembles a long, sticky rope which quickly accumulates a coating of sand and becomes camouflaged. When the eggs hatch, the larvae disperse into the currents for roughly three weeks until they are large enough to settle back into seagrass beds. Breeding can occur during the day or night, and each conch can reproduce up to eight times during the breeding season, which runs from March to November.
Observe, record & share:
O S.SGb-301 – Mating pair: The narrow front end of the male connects with the wide rear end of the female and mating occurs
O S.SGb-302 – Laying eggs: Females lay their eggs over sand in deeper water
O S.SGb-303 – Egg mass: The egg mass resembles a pale, jelly-like rope
Locomotion: The hard, claw-like appendage on the end of the conch’s foot is actually a modified operculum. The operculum is a hard plate that is used to seal off the opening to the shell of most snails as the animal retreats for protection. The queen conch’s operculum has been modified for locomotion as well as to help right the animal when turned upsidedown. The queen conch even uses its operculum to pry itself from a predator’s jaws.
Did You Know?
• Settlement of larval queen conchs from the plankton and metamorphosis into the familiar hard-shelled adult form is triggered when larvae make contact with algae that grow specifically on seagrasses. By using this mechanism, queen conchs ensure their young only develop in safe environments where food is plentiful.
• The queen conch is considered one of the more mobile snails, or gastropods, capable of moving almost 100 m (330 ft) per day.
• Conch shells are made primarily of a mineral called aragonite. Each mineral layer is reinforced by layers of protein, similar to the way a brick wall is reinforced by mortar. As a result the conch’s shell is more than 100 times stronger than pure mineral aragonite, and its construction has inspired engineers in the development of stronger ceramics.
What to do?
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