The indian ocean walkman (Inimicus didactylus) also known as the Demon Stinger fish, Scorpion fish, Devil Stinger fish, Bearded Ghoul is a member of the Inimicus genus of venomous fishes, closely related to the true stonefishes.
It is irregularly surfaced with spines and a knobby appearance. The fish has venomous spines to ward off enemies.
General Description
Adults can attain a body length of up to 26 centimeters in length. The body color is red or sandy yellow 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 wart-like 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 species.
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 indian Ocean walkman has a dorsal fin: composed of 15 to 17 spines and 7 to 9 soft rays. A caudal fin: made up of of 2-4 spines and 4-14 soft rays, with dark bands at basal and subterminal positions. The walkman also has a pelvic fin: which includes one spine and 3-5 soft rays and a pectoral fin: comprised of 10-12 rays. The two most caudal rays of each pectoral fin are detached from the rest of the fin, and angled downwards.
The indian ocean walkman is nocturnal and typically lies partially buried on the sea floor or on a coral head during the day, covering itself with sand and other debris to further camouflage itself.
Due to the fact that this species lives a fairly sedentary life, mostly buried in sand it will often become riddled with parasites, algae and crustaceans due to the amount of time spent motionless waiting for prey. Fortunately for the indian oceanic walkman this isn’t much of a problem as it has the ability to shed its outer layer, effectively getting rid of any unwanted passengers.
When disturbed by a diver or a potential predator, the indian ocean walkman fans out its brilliantly colored pectoral and caudal fins as a warning. Once dug in, it is very reluctant to leave its hiding place. When it does move, it displays an unusual way of moving, it crawls slowly along the seabed, employing the four lower rays (two on each side) of its pectoral fins as legs.
When disturbed they raise the spines along their backs and will usually move off out of harms way, however, if cornered they are able to charge at considerable speed.
The indian ocean walkman is highly dangerous and poisonous with venomous spines along its back.
Eating
They feed nocturnally on fish and invertebrates including crustaceans and cephalopods.Indian ocean walkman fish are masters of camouflage, enabling them to lie in wait for their victims to come close, before lunging forward and inhaling their prey with their large mouths. The indian walkman fish have massive mouths and are able to swallow prey that are over half the size of the walkman itself.
Reproduction
The indian oceanic walkman is oviparous, like most other fish species with fertilization taking place inside the body, followed by the female laying her eggs. The eggs are laid in clear or greenish, gelatinous walls of hollow pear-shaped sacks, which float near the surface. The eggs hatch within 5 days. 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 elongated and slender than the latter with larger development of the pectoral fins.
The breeding season for indian oceanic walkmans is usually in the late spring or early summer.
When it’s time to spawn, some walkmans will travel up to 220 miles to meet their mate. There, they gather on the ocean floor during the day and raise to the surface at night to spawn
Where to Find the Indian Ocean Walkman
The species is usually found in sandy areas and seagrass beds and are mostly solitary creatures, being found in pairs only in the mating season. As the walkmans are masters of camouflage you will find that their habitat varies from fish to fish as no matter the habitat you can be sure indian oceanic walkman fish have adapted to it.
Indian oceanic walkmans usually inhabit shallow waters, but can be also found up to depths of 2194 metres.
Wicked Diving encounters these occasionally in Thailand. However, they are quite common on our muck dives in Komodo.
Conservation
Little is known about the abundance of this species, but it is not generally considered in need of special conservation efforts.
Because of its small size, this species is not fished commercially; however, despite the fact that these fishes are highly venomous, they are collected occasionally for the aquarium trade, where they are sold as “popeyed sea goblins.”
Due to the fact that these prehistoric looking fish are masters of disguise, you will be very fortunate to see one on a dive. Always be careful when sitting down on large sandy areas as an indian oceanic walkman may well be buried in the sand. Also avoid touching any area of hard substrate, the walkman can disguise itself so well that you may think you are touching a rock and inadvertently touch the fish’s venomous spines.
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