Inimicus
Inimicus is a genus of venomous fishes, closely related to the true stonefishes. This genus is a member of the family Synanceiidae.
Species
The members of the genus Inimicus are nearly identical in appearance and behavior, and often confused with one another. There are currently 10 recognized species in this genus:| Species | Common name | Habitat | Distribution | IUCN status |
| Inimicus brachyrhynchus | Marine; tropical; reef-dwelling; demersal | Western Central Pacific | NE* | |
| Inimicus caledonicus | Chinese ghoul, Caledonian stinger, demon stinger | Marine; tropical; reef-dwelling; demersal | Eastern Indian Ocean: Andaman and Nicobar islands. Western Pacific: Australia, Papua New Guinea and New Caledonia. | NE |
| Inimicus cuvieri | Marine; tropical; reef-dwelling; demersal | Western Pacific: South China Sea | NE | |
| Inimicus didactylus | Goblinfish, popeyed sea goblin, demon stinger, devil stinger, longsnout stinger, spiny devilfish, bearded ghoul | Marine; tropical; reef-dwelling; demersal | Eastern Indian and Western Pacific oceans | NE |
| Inimicus filamentosus | Filament-finned stinger, barred ghoul, two-stick stingfish, devil scorpionfish | Marine; tropical; reef-dwelling; demersal | Western Indian Ocean: Red Sea and East Africa to Maldives | NE |
| Inimicus gruzovi Mandritsa, 1991 | Marine; tropical; reef-dwelling; demersal | Western Central Pacific | NE | |
| Inimicus japonicus | Devil stinger | Marine; tropical; reef-dwelling; demersal | Indo-West Pacific: Japan and East China Sea | NE |
| Inimicus joubini | Marine; tropical; reef-dwelling; demersal | Northwest Pacific: Japan and Vietnam | NE | |
| Inimicus sinensis | Spotted ghoul, spotted stonefish | Marine; tropical; reef-dwelling; demersal | NE | |
| Inimicus smirnovi Mandritsa, 1990 | Marine; tropical; reef-dwelling; demersal | Western Central Pacific | NE |
NE: Not Evaluated
Species no longer recognized:
- Inimicus barbatus is a jr. synonym of Inimicus caledonicus
- Inimicus dactylus is a jr. synonym of Inimicus filamentosus
Geographic distribution
Description
Adults are typically 13-25 centimeters in length, and can weigh up to 480 grams. The body color can be a dull yellow, gray, brown, or rust in color with light blotches, and very similar to that of the surrounding sandy or coral seabed in which they are found. This coloration acts as a camouflage which renders them extremely difficult to detect in their natural habitat. The skin is without scales except along the lateral line, and is covered with venomous spines and wartlike glands which give it a knobby appearance. The head is flattened, depressed and concave. The eyes, mouth and nostrils project upwards and outwards from the dorsal aspect of the head. Sexual dimorphism is not believed to occur in this genus.Fin morphology:
- dorsal fin: composed of 15 to 17 spines and 7 to 9 soft rays.
- caudal fin: composed of 2-4 spines and 4-14 soft rays, with dark bands at basal and subterminal positions.
- pelvic fin: composed of one spine and 3-5 soft rays.
- pectoral fin: composed of 10-12 rays. The two most caudal rays of each pectoral fin are detached from the rest of the fin, and angled in a ventral direction. The fish employ these two rays to prop up the forward part of their body, as well as to "walk" along the bottom of the substrate. The ventral surface of the pectoral fins bears broad black bands containing smaller, lighter spots at the basal and distal ends. In I. filamentosus, these bands are attenuated, while the bands of I. sinensis have yellow spots on them. This is a key feature for distinguishing the two species, which are otherwise nearly identical.
Behavior
The paired pectoral fins of these fishes are a remarkable example of their adaptation to life in a benthic environment. No longer useful or necessary for aiding the animal in maneuvering within the water column, the fins have taken on a number of other functions useful to life as a demersal fish. Among these include probing for food items, propping the forward part of the body away from the bottom, and the aforementioned subcarangiform locomotion.
Inimicus is not the only fish that demonstrate this type of ambulation; it has been extensively described in other related benthic Scorpaeniformes fish such as the Sea robin, Flying gurnards, and the Tub Gurnard, Chelidonichthys lucerna. This type of locomotion, based on voluntary and coordinated movements of paired pectoral fins, is believed by some to be a precursor to the later development of similar ambulation in terrestrial vertebrates.
Relevance to humans
Like all known members of the family Synanceiidae, all members of the genus Inimicus possess a complex and extremely potent venom. It is stored in glands at the bases of needle-like spines in their dorsal fins. Upon contact with the dorsal fin, the fish can deliver a very painful, potentially fatal, sting. The venom consists of a mixture of proteolytic enzymes, including stonustoxin, trachynilysin, and cardioleputin. Envenomation results severe and immediate local pain, sometimes followed by shock, paralysis, tissue necrosis, and even death.Despite the obvious risks, one species of Inimicus, I. japonicum, is commercially cultured in Japan. It is used as a food fish there, and it also has applications in Chinese medicine.