Bearded Ghoul

Like other Synancejidae, I. didactylus possesses a powerful venom that is stored in glands at the bases of its dorsal spines that can be injected upon contact. As described above, this species also flashes the undersides of its pectoral fins when disturbed as a warning signal. These, in addition to its natural camouflage, discourage other organisms from feeding on it.

No known predators of I. didactylus are listed.

Anti-predator Adaptations: aposematic ; cryptic

Inimicus didactylus has an elongate body and is without scales, with the exception of 13-15 buried in the lateral line. It is covered with skin glands that have the appearance of warts. No minimums or maximums in length are reported in the literature, but specimens seem to range approximately between 130 mm to 200 mm.

The species has a depressed head that is strongly concave on the dorsal side. The head is also covered with flaps of skin and raised ridges, and tentacles are present on the head, trunk, and fins. Its mouth points up almost vertically, and its eyes protrude visibly outwards. A raised knob at the end of its snout gives it the appearance of having an upturned nose.

The pectoral fins are large and their coloration is significant in identifying the different species of Inimicus. In I. didactylus, the underside of the pectoral fins bears broad dark bands (containing smaller, lighter spots) at the basal and distal ends. The lower 2 rays of its pectoral fins are free from the rest of the fin and used in "walking" along the bottom. This coloration is not sexually dimorphic. The caudal fin has dark bands at basal and subterminal positions. The dorsal fin is composed of 15 to 17 spines and 7 to 9 rays. With the exception of the first 3, the spines are almost entirely incised from membrane.

Other Physical Features: bilateral symmetry ; venomous

Lifespan of this species has not been measured.

This species was previously classified as Scorpaena didactyla, Synanceja didactyla, Synanceja rubicunda, Pelor maculatum, Pelor obscurum, Pelor didactylum, Pelor didactylus, and Inimicus maculatus.

Inimicus didactylus flashes the bright undersides of its pectoral fins as a warning to predators when disturbed. Specialized for its benthic habitat, it has 2 feeler rays on its pectoral fins that probe the seafloor and allow it to "walk" along the bottom. Its eyes and nostrils are located above its dorsal profile as another benthic specialization.

Perception Channels: tactile ; chemical

Little is known about the abundance of this species, but it is not generally considered in need of special conservation efforts. This species is not listed in IUCN's Red List.

US Federal List: no special status

CITES: no special status

In I. didactylus juveniles, the distinctive pigmentation of the pectoral fins does not appear until they have reached a length of about 50 to 60 mm.

Additional information concerning the development of I. didactylus is unavailable, however there are details on the juvenile stages of the larger order, Scorpaeniformes. When larvae hatch, they come equipped with fully developed eyes, range in length from 1.5 to 2.3 mm, and have large yolk sacs. As the larvae develop further, they take on the characteristics of two general morphs: preflexion and postflexion. The former is more elongate and slender than the latter with larger development of the pectoral fins.

Inimicus didactylus is feared by those who come in contact with it due to its painful, venomous spines and resemblence to more deadly stonefishes. Because it is so well concealed, swimmers or divers may accidentally brush against it. It is also commonly caught by prawn trawlers.

Negative Impacts: injures humans (bites or stings, venomous )

Not enough information has been gathered on this species' effect on the ecosystem to evaluate its impact.

Inimicus didactylus acts as a predator in its ecosystems. It is likely that is is host to a multitude of parasites, but there have been no investigations on this subject for this particular species. Given the sensitivity of host specificity in many parasitic organisms, few conjectures can be made across species concerning the parasites of the commercially popular Inimicus japonicus and I. didactylus.

Inimicus didactylus is mainly piscivorous. It lies partially buried in the seafloor with its eyes protruding above the substrate waiting to ambush smaller fishes. Its natural coloration allows it to blend in seamlessly with its environment, making it more difficult for its prey to visually spot it. Rows of teeth lining its jaws and vomer facilitate in feeding I. didactylus.

Primary Diet: carnivore (Piscivore )

Inimicus didactylus is widely distributed in the eastern Indian and western Pacific oceans; however, the species is more common in regions around the Andaman Islands, northern Australia, China, and the Phillipines.

Biogeographic Regions: oriental (Native ); australian (Native )

This species is found in tropical marine regions, particularly brackish water. It is a benthic species that generally occupies moderately deep waters up to 70 m, although it has been reported at depths as shallow as 5 m and as deep as 450 m. It is associated with mangrove swamps and coral reefs.

Range depth: 5 to 450 m.

Habitat Regions: tropical ; saltwater or marine

Aquatic Biomes: reef ; brackish water

Wetlands: swamp

There is little information available on the mating systems of I. didactylus.

There is little information on the reproductive cycle of this species; however, reef scorpaenids generally lay small (0.7 to 1.2 mm) clusters of spherical or slightly ovoid eggs in gelatinous sac-like structures. (An exception to this is Inimicus japonicus, which lays larger, single eggs.)

There is little information on parental investment in I. didactylus.

Dorsal spines (total): 15 - 17; Dorsal soft rays (total): 7 - 9; Analspines: 2; Analsoft rays: 10 - 12

Found inshore (Ref. 75154).

Body colors highly variable and best identified by the patterns on the fins (Ref. 48635). Lower 2 pectoral rays are entirely free and used as "walking" legs and the inner face of the fin is brightly colored (Ref. 37816).Description: Characterized by dark mottling and spots on body; inner black zone with white streaks on inside surface of pectoral fin, with whitish middle zone and outer zone of grey to yellow with pale spots; first three dorsal spines broadly connected with membrane, remaining spines with membrane on less than basal one-third; slightly elevated eyes; absence of scales; longer snout than postorbital length; depth of body about 3.5-3.8 in SL (Ref. 90102).

Found on open sandy or silty substrates of lagoon and seaward reefs. Often buries itself and easily overlooked. Uses pectoral fins to startle predators and shows color during courtship (Ref. 48635). Feeds on small fishes and crustaceans (Ref. 9710). The venom of this fish can be deadly to man. Its ability to camouflage itself by living half-buried presents a real danger. Solitary on sand and mud bottoms (Ref 90102).

aquarium: commercial

分布於印度-西太平洋海域，西起泰國，東到萬那杜，北至琉球群島與中國東南部，南至澳洲。臺灣西南部、東北部及小琉球有分布。

中小型魚類，除學術研究外，不具經濟價值。

體延長，前部粗大，後部稍側扁。顱骨平扁；前額骨甚長，側面深凹。鰾缺如；幽門盲囊大形。體無鱗。具皮瓣，頭部、軀幹部及背鰭硬棘鰭條上皆有。口中大，口裂幾垂直，下頜弧形上突；兩頜具絨毛狀齒，鋤骨具齒，腭骨則無。吻部長，吻長(snout length)大於眼後區長(postocular length)。背鰭連續，具XV-XVII鰭棘，前方三棘分離，第III棘與第IV棘間距較大，自此向後之鰭膜皆深凹而近基底，軟條7-9(通常為 XVI-8)；臀鰭基底略長而低，具II鰭棘，軟條10-12(通常為 11)；胸鰭寬大，下方有2游離鰭條；腹鰭大，具I硬棘，5軟條，鰭膜與體壁相連；尾鰭圓形。體色高度變異；一般胸鰭基部灰色，後接一大形暗色區域，其後是一灰色橫帶，外緣暗色，其內面有白色條紋，有時成灰色圓斑塊狀。

主要棲息於沙泥底質的開放性潟湖與臨海礁石區。具偽裝能力，時常埋藏身體而不容易被發現，藉以守株待兔般快速捕捉過往之小魚與甲殼動物為食。在求偶期期間，會開展胸鰭來展現婚姻色，或是其警告色來驚嚇掠食者。背鰭鰭棘下具毒腺，是海中危險生物。

Inimicus didactylus, also known as sea goblin, demon stinger or devil stinger, is a Western Pacific member of the Inimicus genus of venomous fishes, closely related to the true stonefishes. It can reach a body length of 25 cm (10 in) and is irregularly surfaced with spines and a knobby appearance. The fish has venomous spines to ward off enemies. The fish are nocturnal, and often dig themselves partially into the sandy seabed during the day. The body is red or sandy yellow and well camouflaged on sandy and coral seabeds.