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Species of the genus Pterois (more commonly known as lionfish, turkeyfish, dragonfish) belong to the family Scorpaenidae which includes many known species of venomous marine fish that can live up to 15 years and be up to 40cm standard length. Lionfish are native to the Indo-Pacific however, in 1992 an invasion of P. volitans and P. miles broke out in Key Biscayne, Florida. Today, lionfish have spread all around the Caribbean with several sightings as far north on the Gulf Stream as Rhode Island and Bermuda (Schofield 2009). Efforts to control the populations of P. volitans and P. miles include exemption of fishing permits and limits in the state of Florida as well as community-run derbies. Lionfish are also being served as a delicacy in restaurants.
Sharks and the cornetfish, Fistularia commersonii, are suggested as natural predators (Steinitz 1959) whereas green moray, Gymnothorax funebris, and native groupers have been known to ingest injured lionfish in the Bahamas (Maljkovic et al. 2008).
In a meta-analysis conducted by Cote et al. (2013), the effect of invasive lionfish in the Caribbean was found to be compounded by continuous reproduction and high fecundity of individuals, rapid life-history, and intense competition with native species. Adult females produce between 10,000 and 40,000 eggs per spawning event, releasing eggs on a continuous basis when conditions are favorable. Spawning events have been observed to occur appoximately every 4 days in warm summer months, perhaps increasing in frequency in the more southern extensions of its introduced range leading to an average annual fecundity exceeding 2 million eggs per female. Individuals have also been shown to grow more rapidly in their invaded range when compared to growth rates in the native Pacific range, becoming sexually mature within the first year of life. The meta-analysis also point out that the invasive lionfish have superior competitive abilities over native species, achieving faster growth and maturity than natives. The naivete of prey, being unaccustomed to lionfish as a predator, allow lionfish to indirectly outcompete native piscivorous fish species. Being generalist feeders, lionfish prey on a wide range of native species which decreases the abundance of reef fishes and recruits of larger species that would otherwise outgrow lionfish (Cote et al.2013). Lionfish feed almost continuously, sometimes consuming fish up to almost half their size, effectively slowing stock regeneration of native fish species (Morris and Akins 2009).
Most species of Pterois are reef associated, hiding under rocky outcroppings during the day and moving to deeper water to hunt at night. Pterois volitans and Pterois miles are also mangrove associated, sometimes migrating up estuarine systems into low salinity environments. Usually distributed between 1m and 60m deep, however, some species have been recorded as deep as 300m (REEF 2012) indicating great capability to adapt to numerous conditions. Over the course of ten months, individuals have been recorded to move only an average of 28m, exhibiting high site fidelity (Jud and Layman 2012) and contributing heavily to shaping the community structure along coastline habitats.
Characterized by conspicuous red, white, and black aposematism, or warning colorations, Pterois have numerous (12-13) dorsal spines, 3 anal spines, and 9-11 frilly fin rays (Eschmeyer 1986) that differentiate them from other Scorpaeniformes. The most notable feature of the genus Pterois are the venomous spines located dorsally and anally on the body of the fish. The colorful spines contain toxins and fin rays are used to attract prey and mates. Lionfish pectoral and pelvic fins are spread latero-ventrally while keeping the dorsal fin erect which deters frontal assaults by predators. Pteroine toxins significantly prevent predation and in many instances kill test fish within 30 minutes of injection (Bernadsky and Goulet 1991). At the base of each spine is a venom gland that feeds a narrow groove up the length of the spine. When the spine is depressed, an integumentary sheath exposes the neurotoxin into the puncture wound (Attis 2010).
Individuals of the genus Pterois primarily eat smaller reef fishes as well as crustaceans actively and almost continuously throughout the course of a day with decreased feeding activity during the afternoon. The presence of a bilateral swim bladder aids in highly skilled maneuvering and ambush of prey (Morris and Akins 2009). Often a jet of water is used to disorient and distract prey before they are ingested in one swift motion, usually head first (Albins and Lyons 2012).
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