Aliger gigas

of this species: a figure of A. gigas from '''' (1684). The shell in the figure appears left-right reversed because of the engraving process. The original type was subsequently found, invalidating this designation. History The queen conch was originally described from a shell in 1758 by Swedish naturalist and taxonomist Carl Linnaeus, who originated the system of binomial nomenclature. The specific name is the ancient Greek word '' (), which means "giant", referring to the large size of this snail compared with almost all other gastropod molluscs. Strombus lucifer, which was considered to be a synonym much later, was also described by Linnaeus in Systema Naturae''. Strombidae's taxonomy was extensively revised in the 2000s and a few subgenera, including Eustrombus, were elevated to genus level by some authors. and Petuch and Roberts recombined this species as Eustrombus gigas, and Landau and collaborators (2008) recombined it as Lobatus gigas. In 2020, it was recombined as Aliger gigas by Maxwell and colleagues, which is the current valid name according to the World Register of Marine Species. Phylogeny |caption=A simplified version of the phylogeny and relationships of Strombidae according to Simone (2005)), in this case, included Eustrombus gigas (now considered a synonym of Aliger gigas) and Eustrombus goliath (= Lobatus goliath), which were thus considered closely related. and '''' in Puerto Rico. I is better known as lambi in the French speaking areas of the Caribbeans (most notably Haiti, Guadeloupe and Martinique). == Anatomy ==

Shell The mature shell grows to in length in three to five years while the maximum reported size is . However, even though they only grow to be this maximum length, the thickness of the shell is constantly increasing. The shell is very solid and heavy, with 9 to 11 whorls and a widely flaring and thickened outer lip. The thickness is highly important because the thicker the shell, the better protected it is. Additionally, instead of increasing in size once it reaches its maximum, the outside shell thickens as time goes on- an important indicator of how old the queen conch is. The spire is a protruding part of the shell that includes all of the whorls except the largest and final whorl (known as the body whorl). It is usually more elongated than in other strombid snails, such as the closely related and larger goliath conch, Lobatus goliath that is endemic to Brazil. Historic illustrations '''' (published in 1742 by the Italian physician and malacologist Niccolò Gualtieri) contains three illustrations of adult shells from different perspectives. The knobbed spire and the flaring outer lip, with its somewhat wing-like contour expanding out from the last whorl, is a striking feature of these images. The shells are shown as if balancing on the edge of the lip and/or the apex; this was presumably done for artistic reasons as these shells cannot balance like this. One of the most prized shell publications of the 19th century, a series of books titled '' (published by the French naturalist Jean-Charles Chenu from 1842 to 1853), contains illustrations of both adult and juvenile A. gigas'' shells and one uncoloured drawing depicting some of the animal's soft parts. Almost forty years later, a colored illustration from the Manual of Conchology (published in 1885 by the American malacologist George Washington Tryon) shows a dorsal view of a small juvenile shell with its typical brown and white patterning. In 2005, R. L. Simone gave a detailed anatomical description. A. gigas has a long extensible snout or proboscis with two eyestalks (also known as ommatophores) that originate from its base. The tip of each eyestalk contains a large, well-developed lensed eye, with a black pupil and a yellow iris and a small, slightly posterior sensory tentacle. Inside the mouth of the animal at the end of the proboscis is a radula (a tough ribbon covered in rows of microscopic teeth) of the taenioglossan type. The animal first fixes the posterior end of the foot by thrusting the point of the sickle-shaped operculum into the substrate, then it extends the foot in a forward direction, lifting and throwing the shell forward in a so-called leaping motion. This way of moving is considered to resemble that of pole vaulting, making A. gigas a good climber even of vertical concrete surfaces. This leaping locomotion may help prevent predators from following the snail's chemical traces, which would otherwise leave a continuous trail on the substrate. == Life cycle ==

Aliger gigas is gonochoristic, which means each individual snail is either distinctly male or distinctly female. The number of eggs per egg mass varies greatly depending on environmental conditions such as food availability and temperature. each containing 180,000–460,000 eggs, spend several days developing in the plankton, feeding primarily on phytoplankton. Metamorphosis occurs some 16–40 days from the hatching, It is believed that the mortality rate tends to be lower in matured conchs due to their thickened shell, but it could be substantially higher for juveniles. Estimates have demonstrated that its mortality rate decreases as its size increases and can also vary due to habitat, season and other factors. == Ecology ==

, and the eyestalk on the right is protruded through the siphonal canal. The outer surface of the shell is covered by periphyton , feeding on A. gigas'' in Dry Tortugas National Park, Florida, June 2010 , inside a subadult shell of A. gigas'' Distribution Aliger gigas is native to the tropical Western Atlantic coasts of North and Central America in the greater Caribbean tropical zone. Aruba (Netherlands Antilles); Barbados; the Bahamas; Belize; Bermuda; North and northeastern regions of Brazil (though this is contested); Its depth range is limited by the distribution of seagrass and algae cover. In heavily exploited areas, the queen conch is more abundant in the deepest range. usually in association with turtle grass (species of the genus Thalassia, specifically Thalassia testudinum and also Syringodium sp.) The critical nursery habitats for juvenile individuals are defined by a series of characteristics, including tidal circulation and macroalgal production, which together enable high rates of recruitment and survival. A. gigas is typically found in distinct aggregates that may contain several thousand individuals. Diet Strombid gastropods were widely accepted as carnivores by several authors in the 19th century, a concept that persisted until the first half of the 20th century. This erroneous idea originated in the writings of Jean-Baptiste Lamarck, who classified strombids with other supposedly carnivorous snails. This idea was subsequently repeated by other authors, but had not been supported by observation. Subsequent studies have refuted the concept, proving beyond doubt that strombid gastropods are herbivorous animals. In common with other Strombidae, Aliger gigas is a specialized herbivore, seagrass The green macroalgae Batophora oerstedii is one of its preferred foods. parasites, which are spore-forming, single-celled microorganisms, initially establish themselves in large vacuolated cells of the host's digestive gland, where they reproduce freely. Crustaceans are also conch predators, such as the blue crab Callinectes sapidus, the box crab Calappa gallus, the giant hermit crab Petrochirus diogenes, the spiny lobster Panulirus argus and others. and the porcupine fish Diodon hystrix), loggerhead sea turtles (Caretta caretta) and humans also eat the queen conch. == Uses ==

, all having been fished and showing the cut in the spire. This cut is used to sever the columellar muscle allowing the soft parts to slide out. The total annual harvest of meat of A. gigas ranged from 6,519,711 kg to 7,369,314 kg between 1993 and 1998, later production declined to 3,131,599 kg in 2001. Queen conch shells were used by Native Americans and Caribbean Indians in a wide variety of ways. South Florida bands (such as the Tequesta), the Carib, the Arawak and Taíno used conch shells to fabricate tools (such as knives, axe heads and chisels), jewelry, cookware and used them as blowing horns. In Mesoamerican history, Aztecs used the shell as part of jewelry mosaics such as the double-headed serpent. The Aztecs also believed that the sound of trumpets made from queen conch shells represented divine manifestations, and used them in religious ceremonies. In central Mexico, during rain ceremonies dedicated to Tlaloc, the Maya used conch shells as hand protectors (in a manner similar to boxing gloves) during combat. Brought by explorers, queen conch shells quickly became a popular asset in early modern Europe. In the late 17th century they were widely used as decoration over fireplace mantels and English gardens, among other places. and traditionally as doorstops or decorations by families of seafaring men. In modern culture, queen conch shells are often represented in everyday objects such as coins and stamps. Very rarely (about 1 in 10,000 conchs), Though these pearls occur in a range of colors corresponding to the colors of the interior of the shell, pink specimens are the most valuable. These pearls are considered semi-precious, Research into the conch shell's unique architecture is currently under way at MIT. == Status ==

Threats , British Virgin Islands, a heap consists of thousands of empty queen conch shells, discarded after their flesh was taken for human consumption. Overfishing Queen conch populations have been rapidly declining throughout the years and have been mostly depleted in some areas in the Caribbean because they are highly sought after for their meat and their value. Within the conch fisheries, one of the threats to sustainability stems from the fact that there is almost as much meat in large juveniles as there is in adults, but only adult conchs can reproduce, and thus sustain a population. In many places where adult conchs have become rare due to overfishing, larger juveniles and subadults are taken before they ever mate. The abundance of Aliger gigas is declining throughout its range as a result of overfishing and poaching. Especially because of overfishing, many pockets of conch communities fall below the critical level needed for reproducing. A 2019 study predicted overfishing could lead to the extinction of queen conchs in as little as ten years. Additionally, if the conch fishery collapses, it could potentially leave over 9,000 Bahamian fishers out of work. Imposex compounds. This condition is triggered by exposure to organic tin compounds such as tributyltin (TBT) and triphenyltin (TPT), is irreversible, and can have severe consequences for the species, ranging from individual sterilization to potential population collapse. Organotin compounds are commonly used as biocides and antifouling agents, added to marine paints to prevent organisms from growing on the hulls of boats and ships. As a result, high concentrations often accumulate in the waters around shipyards and docking areas, posing a serious threat to nearby marine life through prolonged exposure. A study carried out in 2025 revealed that the queen conch is particularly sensitive to organotin compounds like TBT. The study, conducted in the coastal waters of the Caribbean, established a clear correlation between the prevalence and intensity of imposex in female conchs and proximity to marine traffic and harbor areas. In areas of high contamination, female conchs developed male reproductive organs, often leading to reproductive failure due to anatomical interference with egg laying. the queen conch provides region-specific relevance for the tropical Caribbean, where it is both economically valuable and culturally significant. The study's data suggest that even low levels of TBT in the water column can induce measurable imposex. No international regional fishery management organization exists for the whole Caribbean area, but in places such as Puerto Rico and the Virgin Islands, queen conch is regulated under the auspices of the Caribbean Fishery Management Council (CFMC). The species is listed in Appendix II of the Convention on International Trade in Endangered Species (CITES) meaning international trade (import/export) in the species and its parts and derivatives is regulated by the CITES permitting system. In 1995 CITES began reviewing the biological and trade status of the queen conch under its "Significant Trade Review" process. These reviews are undertaken to address concerns about trade levels in an Appendix II species. Based on the 2003 review, Queen conch meat continues to be available from other Caribbean countries, including Jamaica and Turks and Caicos, which operate well-managed queen conch fisheries. The Bahamas National Trust is building awareness by educating teachers and students through workshops and an awareness campaign which includes the song Conch Gone. In parts of the world where queen conch fishing is legal, only adult conchs can be fished. The rule is to let each conch have ample time to reproduce before taken out of its habitat, potentially leading to a more stable population. However, this rule has not been followed by countless fishers. On many islands, subadults provide the majority of the harvest. In 2022, the US NOAA conducted a review of A. gigas populations throughout its range; the study places the species at a moderate risk of extinction over the next 30 years. The study also requested, and received comments from management agencies, nations and associations throughout the Caribbean regarding the status of the species, and implications of listing the species as Threatened under the US Endangered Species Act. == References ==