Scorpion fishes

Scientific name : Scorpaenidae

Scorpaenidae are a quite large fish family, present in almost all the world's seas. Usually they are heavy fishes, bad swimmers, living on the bottom, where they hide to catch their preys: they are masters of camouflage. The exception are the lion fishes (subfamily Pteroinae), that are very easy to spot with their long fins, and that swim (even if slowly).
All those fishes have venomous spines (the spiny rays of the dorsal fin). Few species are lethal to humans, but the sting can be extremely painful.
Scorpion fishes are easy to observe, because they do not like to move around and usually they are not wary of divers. The main difficulty can be to locate them.
They are certainly not handsome, anyway many species are fascinating due to their shape and colour, and rank at the first places in the whishes list of many photographers.
Scorpaenidae family, belonging to the Scorpaeniformes order, is characterized by large head and mouth, a spiny bony ridge on the cheek. Usually massive body. Many scattered spines, but only the spiny rays of the dorsal fin are venomous. Having a longitudinal groove and connection with a basal venom gland, they can inject a powerful toxin.
Pectoral fins are well developed, especially in the lion fishes.
In comparison with the typical fish, scorpion fishes has no gas bladder, therefore they have a negative buoyancy and difficulties in swimming.
Many species are ornate with skin flaps and tentacles, contributing to camouflage.
They live in many environments, always on or very close to the bottom. Common in all the reef parts.
They prey upon fish and crustaceans, as ambush predators, jumping on the prey with a sudden sprint. Lion fishes often use the pectoral fins to corral the preys toward the mouth.
The femal releases large masses of planktonic eggs.
Lesser groups, belonging to the Scorpaeniformes order, are often confused with the more familiar scorpion fishes: they are for example the Aploactinidae (velvet fishes) and Tetrarogidae (wasp fishes) families. Both have elongated shape and typical fins.
All scorpion fishes are venomous. Their venom, injected through the dorsal fin's spiny rays, is a mix including neurotoxins (with action on the nervous system). Toxins are proteins, and they are denaturated by the heat losing their power. A useful first aid for a diver stung by a scorpion fish is local application of heat (warm water, warm air, warm metal surfaces).
Few species are deadly for humans, like the stone fishes (Synanceia spp.). The stings of most scorpion fishes are anyway very painful.