Queen conch (Strombus gigas)
|Size||Length: 20 - 25 cm (2)|
Listed on Appendix II of CITES (1).
This gastropod produces a large spiral shell with spines that are thought to be for protection (3). The shell has a wide, flared lip that is a rich pink colour (4). Within the shell, the gastropod’s head has two pairs of tentacles; the larger ones carry eyes whilst the smaller pair provides a sense of smell and touch. The large foot is visible at the lip of the shell (3). The large, beautiful shell has been prized by tourists in recent years, but was previously valued more for its meat (2).
The queen conch was previously found throughout the coastal waters of northern South America, north through the Caribbean and Bahamas to south Florida and Bermuda. Today the species has declined in numbers throughout much of this range (5).
Adults are associated with shallow warm waters usually with a sandy substrate, where there is abundance of seagrasses, such as turtle (Thalasia testuinum), and manatee grass (Syringodium filiforme) or mats of microalgae (5).
Queen conch have internal fertilization, after which the female spawns thousands of eggs in a long tubular egg mass. Spawning tends to occur during the summer; the large egg masses may take up to 36 hours to produce and can hold between 310,000 and 750,000 eggs. These egg masses are covered with sand to provide camouflage and the larvae emerge after around 5 days. A single female will spawn between 6 and 8 times during one season. Larvae, known as veligers, float in the open ocean, feeding on phytoplankton and may drift a considerable distance from the site where they emerged, although evidence for this is limited. Between 18 and 40 days later (depending on conditions) the larvae settle into the sand and metamorphose into the adult form. Adult queen conch have been observed to migrate to deeper waters as they increase in size, and seasonal migrations during the summer months, in order to group together and spawn, have also been recorded (5).
Conch move by an unusual ‘hopping’ motion whereby the foot is thrust against the bottom, causing the shell to rise and then be thrown forward. Queen conch are most active during the night and graze on algae and detritus using their extendable proboscis (5).
Queen conch have provided a staple meat source in the Caribbean region for centuries and in recent times have been extensively overfished for this resource. Their flesh is also used as fishing bait and the shells can be sold for the tourist trade (6). The tendency of conch to aggregate in shallow waters in order to spawn in the summer months has allowed them to be easily exploited. The population is now in decline throughout most of the region (5). Fishing for conch has been banned in Florida and Bermuda, but so far populations in these areas are showing few signs of recovery (9).
The Queen conch is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), thus requiring an export permit for trade to occur (7). In 1996, the countries within this conch’s range recognised the importance of the species and adopted an International Queen Conch Initiative to promote a common international management strategy for the queen conch resource in the Caribbean region (8). It has been suggested that harvesting limits or marine reserves will allow the species to recover from overfishing in the past. Queen conches have been bred in captivity but attempted reintroduction programmes have so far proven unsuccessful (6).
For more information on this species and its conservation, see:
Caribbean Fisheries Management Council:
Conch Heritage Network:
Authenticated (06/06/05) by Dr Jo Gascoigne of the University of Wales, Bangor.
- Alga: a collection of taxonomically unrelated groups that share some common features but are grouped together for historical reasons and for convenience. They are of simple construction, and are mainly photoautotrophic, obtaining all their energy from light and carbon dioxide, and possess the photosynthetic pigment, chlorophyll A. They range in complexity from microscopic single cells to very complex plant-like forms, such as kelps. Algal groups include blue-green algae (cyanobacteria), red algae (rhodophyta), green algae (chlorophyta), brown algae and diatoms (chromista) as well as euglenophyta.
- Larvae: stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
- Metamorphosis: to change shape or form, such as from a caterpillar to a moth or butterfly, a tadpole to a frog or toad.
- Microalgae: tiny seaweeds with only one cell which often group together to form a mat or layer over the seabed and provide food for many animals
- Plankton: aquatic organisms that drift with water movements; may be either phytoplankton (plants), or zooplankton (animals).
- Proboscis: a tubular protrusion from the anterior of an animal (e.g. the trunk of an elephant).
UNEP-WCMC database (August, 2002)
- Wye, K. (1991) The Illustrated Encyclopedia of Shells. Quintet Publishing Limited, London.
Enchanted Learning (August, 2002)
Animal Diversity Web (August, 2002)
Caribbean Fisheries Management Council (August, 2002)
American Museum of Natural History (August, 2002)
- Gascoigne, J. (2005) Pers. comm.
CITES (August, 2002)
International Queen Conch Initiative (August, 2002)