Did you know that the Lionfish, an invasive fish which eats other fish and has no known predators, may have been introduced as a result of Hurricane Andrew destroying an aquarium, and now threatens the Atlantic Ocean’s ecology.
Pterois, commonly known as lionfish, is a genus of venomous marine fish found mostly in the Indo-Pacific. Pterois is characterized by conspicuous warning coloration with red, white, creamy, or black bands, showy pectoral fins and venomous spiky fin rays. Pterois are classified into a number of different species, but Pterois radiata, Pterois volitans and Pterois miles are the most commonly studied. Pterois are popular aquarium fish and are readily utilized in the culinary world
Pterois range in size from 2.44in to 16.69in cm with typical adults measuring 14.96in cm and weighing an average of 1.05 LBS. They are well known for their ornate beauty, venomous spines and unique tentacles. Juvenile lionfish have a unique tentacle located above their eye sockets that varies in phenotype between species. It is suggested that the evolution of this tentacle serves to continually attract new prey; studies also suggest that it plays a role in sexual selection
Pterois can live from five to fifteen years and have complex courtship and mating behaviors. Females release two mucus-filled egg clusters frequently, which can contain as many as fifteen thousand eggs. Studies on Pterois reproductive habits have increased significantly in the past decade. All the species are aposematic: they have conspicuous coloration with boldly contrasting stripes and wide fans of projecting spines, advertising their ability to defend themselves.
Pterois miles hunting glassfish
According to a study that involved the dissection of over 1,400 lionfish stomachs from Bahamian to North Carolinian waters, Pterois prey mostly on small fish, invertebrates and mollusks in large amounts, with some specimens’ stomachs containing up to six different species of prey. The amount of prey in lionfish stomachs over the course of the day suggest that lionfish feed most actively from 7:00–11:00 am, with decreased feeding throughout the afternoon. Lionfish are skilled hunters, 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. Researchers have also noted that lionfish blow jets of water while approaching prey, apparently in order to disorient them.
Predators and parasites
Aside from instances of larger lionfish individuals engaging in cannibalism on smaller individuals, adult lionfish have few identified natural predators. This is likely due to the effectiveness of their venomous spines. Moray eels (family Muraenidae), bluespotted cornetfish (Fistularia commersonii) and large groupers, like the tiger grouper (Mycteroperca tigris) and Nassau grouper (Epinephelus striatus), have been observed preying on lionfish. It remains unknown, however, how commonly these predators prey on lionfish. Sharks are also believed to be capable of preying on lionfish with no ill-effects from its spines. Park officials of the Roatan Marine Park in Honduras have attempted to train sharks to feed on lionfish as of 2011 in an attempt to control the invasive populations in the Caribbean. Predators of larvae and juvenile lionfish remain unknown, but may prove to be the primary limiting factor of lionfish populations in their native range.
Parasites of lionfish have rarely been observed and are assumed to be infrequent. They include isopods and leeches.
Hazard to humans
Lionfish are known for their venomous fin rays, a feature that is uncommon among marine fish in the East Coast coral reefs. The potency of their venom makes them excellent predators and poisonous to fishermen and divers. Pterois venom produced negative inotropic and chronotropic effects when tested in both frog and clam hearts and has a depressing effect on rabbit blood pressure. These results are thought to be due to nitric oxide release. In humans, Pterois venom can cause systemic effects such as extreme pain, nausea, vomiting, fever, breathing difficulties, convulsions, dizziness, redness on the affected area, headache, numbness, paresthesia (pins and needles), heartburn, diarrhea, and sweating. Rarely, such stings can cause temporary paralysis of the limbs, heart failure and even death. Fatalities are common in very young children, the elderly, those with a weak immune system or those who are allergic to their venom. Their venom is rarely fatal to healthy humans, but some species have enough venom to produce extreme discomfort for over a period of several days. However, Pterois venom is a danger to allergic victims as they may experience anaphylaxis, a serious and often life threatening condition that requires immediate emergency medical treatment. Severe allergic reactions to Pterois venom include chest pain, severe breathing difficulties, a drop in blood pressure, swelling of the tongue, sweating, runny nose, or slurred speech. Such reactions can be fatal if not treated.