The crocodilefish (Papilloculiceps longiceps), also known as the tentacled flathead or Western Indian Ocean crocodilefish, has a unique character due to its unusual shaped jaw. The fish sits flat and unmoving on reefs with its crocodile like snout and tentacled eyes picking up every passing movement, ready to snap up any passing morsel. They have a primeval appearance, almost looks as though they’ve escaped from Jurassic Park.
They are part of the order Scorpaeniformes which also contains the scorpion fish family and are ambush predators. To assist their camouflage they have tentacles on their eyes, which help to break up the outline of the eye, making it much harder for their prey and a diver to spot them.
They are found in the Western Indian Ocean in depths from one to 18 meters. Usually they are on a reef or alongside it, in sandy or rubble filled areas where their camouflage is most effective.
The crocodilefish is a mottled green, brown and grey color and its outline is broken up by the camouflage pattern.
The pectoral fins are spread to the side when it is sitting on the bottom and are also camouflaged. They have a large pair of eyes which are camouflaged by small tentacles that drop down over the eye from the upper lid, making them extremely difficult to spot. As the name implies they have a protruding jaw which resembles that of a crocodile and a row of fierce looking teeth allowing them to clamp onto their prey. They have a long body widening at the center and tapering off to the tail and grow up to 70 centimeters. When sitting normally on the bottom their dorsal fin is down but if approached by a diver they will often raise the dorsal fin as a warning, as if to say here I am and you have spotted me but I saw you first.
These fish are extremely well camouflaged with the mottled pattern breaking up their outline and with the small tentacles on their eyes helping to break up the outline of the eye, the only spot that cannot be easily camouflaged. When they settle into a spot on sand they lightly flap their pectoral fins which lifts some sediment and drops it down on them, breaking up their outline even further. Being ambush predators they sit and wait for their prey to come to them, always watching through their tentacled eyes. They wait for the prey to come and with one snap of their crocodile jaws they will grab and swallow them.
Crocodilefish eat almost anything that will fit into their mouths and to some extent their diet is dictated by whatever swims past. Any fish, squid crustacean unlucky enough to swim within proximity of their jaws will end up in them.
Some aquarists keep the crocodilefish as specialty items but generally only the large commercial aquariums will keep them and they require a large tank and prefer live food.
A creative video, comparing and contrasting two Crocodilefish; one on a reef and one in a grassy patch: