Queen triggerfish (Balistes vetula)
|French:||Baliste Royal, Bourse|
|Spanish:||Cach'àö'à´a, Cach√∫a, Cachúa, Cachuda, Cochino, Oldwife, Peje Puerco, Pejepuerco, Pejepuerco Cachuo, Pez Puerco, Puerco|
|Size||Maximum length: 60 cm (2)|
Classified as Vulnerable (VU) on the IUCN Red List 2007 (1).
The deep-bodied queen triggerfish has suitably regal colouring; it is a flamboyant, and variable, mixture of blue, green and yellow, which can be light or dark depending on the fish’s mood (3), and vivid blue lines pattern the head and the fins (2). Triggerfish are named after the spines situated on their backs. The first large spine can be erected and then locked into place by the second smaller spine which fits into a groove in the first spine (3). This clever locking mechanism enables triggerfish to wedge themselves into crevices when they feel threatened (3), and the first spine can only be folded away when the second ‘trigger’ spine is depressed (2). The eyes, which are set high on the fish’s head (2), are capable of moving independently of each other (4), and the small mouth bears large, stout teeth (2).
Occurs in the Atlantic Ocean (1), from Bermuda and the northern Gulf of Mexico, south to Brazil, and east to Ascension Island and the eastern Atlantic (2).
The queen triggerfish inhabits coral reefs and nearby sandy and rubble areas, from shallow waters down to depths of 50 metres (3).
The queen triggerfish is often found drifting close to the bottom, where it feeds on a range of molluscs, crustaceans and echinoderms (4). The strong jaws and long teeth of this fish enable it to bite through the hard body parts of these marine creatures with ease (4). It specialises on feeding on a particular sea urchin (Diadema antillarium), and has evolved an ingenious way of tackling this spiny prey; it blows water under the sea urchin to overturn it, exposing the part of the sea urchin where the spines are shortest (2).
Little information is available on the breeding biology of this species, although it is known that triggerfish lay eggs which stick to corals, rocks and algae (4). The eggs are somewhat protected by being camouflaged (4), and are also apparently guarded by the male (2). As adults, queen triggerfish are protected by the erectile spine on their backs. If threatened, the triggerfish will retreat into a crevice in the reef, the spine on its back locks into position, and the predator is unable to remove the fish from its shelter (4).
Little information is available on the status of the queen triggerfish, but it is known that this striking species is a commercially important food fish (5), vulnerable to trapping and spear-fishing (6). It may also be susceptible to the detrimental impacts of changes in the abundance of its primary food source; in 1983 and 1984, the sea urchin Diadema antillarum underwent massive mortality on reefs throughout the Caribbean. Luckily, the queen triggerfish shows some resilience to such events, as it was found that the fish sought out alternative prey species (5) (7).
The queen triggerfish occurs in a number of protected marine areas throughout its range, such as Saba Marine Park and Hol Chan Marine Reserve in the Caribbean, of which some areas are designated no-fishing zones (8).
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- Crustaceans: diverse group of arthropods (a phylum of animals with jointed limbs and a hard chitinous exoskeleton) characterised by the possession of two pairs of antennae, one pair of mandibles (parts of the mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, slaters, woodlice and barnacles.
- Echinoderms: a group of marine animals that usually have a spiny skin. This group includes starfish, sea urchins and sea cucumbers.
- Molluscs: a diverse group of invertebrates, mainly marine, that have one or all of the following; a horny, toothed ribbon in the mouth (the radula), a shell covering the upper surface of the body, and a mantle or mantle cavity with a type of gill. Includes snails, slugs, shellfish, octopuses and squid.
IUCN Red List (April, 2008)
- Lieske, E. and Myers, R. (2001) Coral Reef Fishes. HarperCollins Publishers, London.
- Wood, E. and Wood, L. (2000) Reef Fishes, Corals and Invertebrates of the Caribbean including Bermuda. New Holland Publishers, London.
- Snyderman, M. and Wiseman, C. (1996) Guide to Marine Life: Caribbean, Bahamas, Florida. Aqua Quest Publications Inc, New York.
- Garrison, V.H., Rogers, C.S., Beets, J. and Friedlander, A.M. (2004) The habitats exploited and the species trapped in a Caribbean island trap fishery. Environmental Biology of Fishes, 71: 247 - 260.
- Roberts, C.M. (1995) Effects of fishing on the ecosystem structure of coral reefs. Conservation Biology, 9(5): 988 - 995.
- Reinthal, P.N., Kensley, B. and Lewis, S.M. (2008) Dietary shifts in the queen triggerfish, Balistes vetula, in the absence of its primary food item, Diadema antillarum. Marine Ecology, 5(2): 191 - 195.
- Polunin, N.V.C. and Roberts, C.M. (1993) Greater biomass and value of target coral-reef fishes in two small Caribbean marine reserves. Marine Ecology Progress Series, 100: 167 - 176.