| Red lionfish | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Scorpaeniformes |
| Family: | Scorpaenidae |
| Subfamily: | Pteroinae |
| Genus: | Pterois |
| Species: | P. volitans |
| Binomial name | |
| Pterois volitans (Linnaeus, 1758) |
|
The red lionfish (Pterois volitans) is a venomous coral reef fish in the family Scorpaenidae, order Scorpaeniformes. P. volitans is natively found in the Indo-Pacific region, but has become a huge invasive problem in the Caribbean Sea and along the East coast of the United States along with a similar species, Pterois miles. Red lionfish are clad in white stripes alternated with red, maroon, or brown. Adults can grow as large as 17 inches (43 cm) in length while juveniles may be shorter than 1 inch (2.5 cm).[1] They can live up to 10 years.[2] The fish has large venomous spines that protrude from the body like a mane, giving it the common name of the lionfish. The venomous spines make the fish inedible or deter most potential predators. Lionfish reproduce monthly and are able to quickly disperse during their larval stage for expansion of their invasive region. There are no definitive predators of the lionfish, and many organizations are promoting the harvest and consumption of lionfish in efforts to prevent further increases in the already high population densities.
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P. volitans has very few fish that resemble it, with the most common being Pterois miles, the devil firefish. The visual distinguishable trait between the two similar species is the extra dorsal and anal fin ray present on P. volitans. It has also been reported that P. volitans reaches to the Western and Central Pacific and Western Australia. P. miles is found in the Red Sea, Persian Gulf, and Indian Ocean.[3] Mitochondrial DNA analyses have proven that the two species are genetically different.[4] It is unknown whether or not the two species hybridize, although no differences have been found in their reproductive biology.[5] Both species are considered invasive along the East Coast of the United States, with approximately 93% of the population consisting of P. volitans. Genetic studies have shown that a strong founder effect has occurred, and there is low genetic diversity in the populations in the Atlantic.[6]
The red lionfish is part of the family Scorpaenidae, order Scorpaeniformes, and suborder Pteroidae. Lionfish have distinctive red, maroon, and white vertical stripes. Fleshy tentacles protrude from above the eyes and below the mouth. The fish have fan-like pectoral fins with venomous spines, 13 long separated dorsal spines, and 3 anal spines. Lionfish larvae are planktonic, and adults can be as large as 17 inches (43 cm) in length.[1] Lionfish generally inhabit rocky and coral reef areas, and can be found at depths between 1 metre (3.3 ft)in shallow mangroves and 131.5 metres (431 ft). They are most often found under ledges or in shaded cave areas, in an almost motionless state. As they become more abundant, there have been claims of the fish also being found in bays and estuaries. The most distinguishable characteristic of the red lionfish, as well as all scorpionfishes, are the venomous spines protruding from the body. An extremely showy and ornate fish such as the lionfish should be an easy target for predators, but the large spines act as a great defense. The spines are incorporated into certain fins of the fish, and have venom glands at the base of the spine. These glands protect the fish from predation, delivering a painful and potentially fatal venomous “sting” to predators or a human that may come in contact with a lionfish.
P. volitans occurs natively in the Indo-Pacific region, including the Western and Central Pacific and off the coast of Western Australia.
They are mainly a solitary species and courting is the only time when aggregate, generally 1 male with several females.[2] Both P. volitans and P. miles are gonochoristic, only showing sexual dimorphism during reproduction. Similar courtship behaviors are observed in all Pterois species. These behaviors include circling, sidewinding, following, and leading. The lionfish are mostly nocturnal, leading to the behaviors typically around nightfall and continuing through the night. After courtship the female releases two egg masses that are fertilized by the male before floating to the surface. The eggs are kept together by a mucus which disintegrates within a few days to release larvae.[7] Data collected suggests that lionfish can reproduce monthly, through all seasons of the year.[8]
Although little is known about the larval stage of the lionfish, some traits of the larvae include a large head, a long, triangular snout, long, serrated head spines, a larve pelvic spine, and coloration only in the pelvic fins. Larvae hatch 36 hours after fertilization.[2] The larvae are good swimmers and can eat small ciliates just 4 days after conception.[2] The larval stage is the shortest stage of the lionfish’s life, with a duration of about one month.[9]
There has been very little documentation of any true predators of the lionfish. It has been suggested that larger fish and sharks that should be able to eat the lionfish have not recognized the lionfish as prey due to the novelty of the fish in the invaded areas. Lionfish have, however, infrequently been found in the stomachs of grouper.[10] The lionfish themselves are voracious feeders and have outcompeted and filled the niche of the overfished snapper and grouper. When hunting, they corner prey using their large fins and then use their quick reflexes to swallow the prey whole. They hunt primarily from late afternoon to dawn. High rates of prey consumption, a wide variety of diet, and increasing abundance of the fish lead to concern that the fish may have a very active role in the already declining trend of fish densities.[11] As the fish become more abundant, they are becoming a threat to the fragile ecosystems that they have invaded. Between outcompeting similar fish and having a large diet, the lionfish is drastically changing and disrupting the food chains that hold the marine ecosystems together. As these chains are distrupted, we continue to see declining densities of other fish populations, as well as a decline in the overall diversity of coral reef areas.
Lionfish have venomous dorsal spines that are used purely for defense. When threatened, the fish often faces its attacker in an upside down posture which brings its spines to bear. However, a lionfish's sting is usually not fatal to humans. If a human is envenomed, that person will experience extreme pain, and possibly headaches, vomiting, and breathing difficulties. A common treatment is soaking the afflicted area in hot water, as very few hospitals carry specific treatments.[12][13][14] However, immediate emergency medical treatment is still advised, as some people are more susceptible to the venom than others.
Two of the fifteen species of Pterois, P. volitans and P. miles, have established themselves as significant invasive species off the East Coast of the United States and in the Caribbean. About 93% of the invasive lionfish population is P. volitans, also known as the Red Lionfish.[6] The red lionfish is found off the East Coast of the United States and the Caribbean Sea, and was likely first introduced off the Florida coast in the early to mid- 1990s.[15] Adult lionfish specimens are now found along the United States East Coast from Cape Hatteras, North Carolina, to Florida, and in Bermuda, the Bahamas, and throughout the Caribbean, including the Turks and Caicos, Haiti, Cuba, Dominican Republic, Puerto Rico, St. Croix, Belize, Honduras, Aruba and Mexico.[16]