Pterois volitans/ miles
| Ecological Descriptors
Invasive species, presumed to be in Western Atlantic following release of pet fish. Preys on small reef fish, particularly Damselfishes.
Two species are found in the area: The Red Lionfish, P. volitans, from the central and West Pacific and Western Australia, and the Common Lionfish, P. miles, from the remainder of the Indian Ocean. These can be distinguished by DNA testing, and also morphologically on the basis of the following four overlapping characteristics: P.volitans has an modal number of 11 soft dorsal rays, while P. miles has 10: P. a modal number of 7 soft anal rays, while P. miles has 6: P. volitans has a longer pectoral fin than P. miles; spots on the soft dorsal fin are larger in P. volitans than in P. miles. Atlhough both species are found in the Greater Caribbean. P. miles is far rarer (<10%).
Interestingly, new genetic analysis (Wilcox et al Journal of Heredity Jun 2017) indicates that the "Red Lionfish" is actually a hybrid!! (Of P. miles and another species, Russell's Lionfish (P. russeleii)..there is a (unproven) suggestion that "hybrid vigour" (heterosis) may be a reason for their success ...
Both species have venomous spines: 13 dorsal spines, 1 on each pectoral fin and 3 on the anal fin. The venom consists of a number of heat -labile large proteins including a hyaluronidase, pain-producing factor, capillary permeability factor, and toxic factors which induce muscular fibrillation.
Adults : Body moderately laterally compressedwith a large spiney head . The forehead has a steep profile and has a long tentacle over eye. Body pale red to whitish, with ~8 broad brown to blackish bars, each one separated by several thin dark bars. The head has similar bars, those on rear of head diagonal and extending onto chest. Some fins have whitish tips.
Juveniles : Predominantly transparent with some black stripes and relatively large spots.
Inhabit lagoon and seaward reefs from turbid inshore areas to depths of 50 m. Often solitary, they hide in unexposed places at daytime often with head down and practically immobile.
Lionfish are skilled hunters of small fishes, shrimps, and crabs, using specialized bilateral swim bladder muscles to provide exquisite control of location in the water column, allowing the fish to alter its center of gravity to better attack prey. The lionfish then spreads its large pectoral fins and swallows its prey in a single motion. They blow jets of water while approaching prey, apparently to disorient them. In addition to confusing prey, these jets of water also alter the orientation of the prey so that the smaller fish is facing the lionfish. This results in a higher degree to predatory efficiency as head-first capture is easier for the lionfish - In general, when smaller fish escapes from a possible danger, they always do so opposite to current.
The following have been known to predate on Lionfish, but the extent of which is unknown: Moray eels (family Muraenidae), large groupers e.g.Nassau grouper (Epinephelus striatus).
Has numerous venomous spines: 13 Dorsal, 1 on each pelvic fin and 3 on the anal fin. The sting can be treated by heating the afflicted part (as the proteinaceous venom is heat labile) and application of corticosteroids. It is one of the most venomous fish in Antigua (but not poisonous.).
This species is a broadcast spawner and is capable of reproducing year-round. Pelagic juveniles (20-35 days duration) travel over great distances and is one reason for their broad geographical range/ invasiveness. Length at maturation ~19cm. Maximum reported age 10 years.
Courtship phase between the fish occurs before dark, leading into late night. The male and female circle each other, before ascending near the water surface. The female releases eggs and the male fertilizes it, the egg clumps float. Embryos form in adhesive mucus, within a few days becoming free floating larvae. Larvae hatching size is estimated to be 1.5 mm. During a mating session, females can lay up to 30,000 eggs during spawning. In warm water, reproduction is easy across the year as it is an asynchronous batch spawner.
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