A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through convergent evolution they have independently evolved external superficial fish-like body plans ideal for their marine environments, including most numerously fish, but also mammals such as cetaceans, and even extinct ancient marine reptiles such as various known species of ichthyosaurs. Most species have only one dorsal fin, but some have two or three.
Teleostei, members of which are known as teleosts, is by far the largest infraclass in the class Actinopterygii, the ray-finned fishes, containing 96% of all extant species of fish. Teleosts are arranged into about 40 orders and 448 families. Over 26,000 species have been described. Teleosts range from giant oarfish measuring 7.6 m (25 ft) or more, and ocean sunfish weighing over 2 t, to the minute male anglerfish Photocorynus spiniceps, just 6.2 mm (0.24 in) long. Including not only torpedo-shaped fish built for speed, teleosts can be flattened vertically or horizontally, be elongated cylinders or take specialised shapes as in anglerfish and seahorses.
The Scorpaenidae are a family of mostly marine fish that includes many of the world's most venomous species. As their name suggests, scorpionfish have a type of "sting" in the form of sharp spines coated with venomous mucus. The family is a large one, with hundreds of members. They are widespread in tropical and temperate seas, but mostly found in the Indo-Pacific. They should not be confused with the cabezones, of the genus Scorpaenichthys, which belong to a separate, though related, family, Cottidae.
Synanceia verrucosa is a species of venomous fish in the family Synanceiidae, commonly known as the reef stonefish. It is the most widespread species of stonefish, mostly found in shallow waters of the Red Sea and the Indo-Pacific. It is the deadliest fish in the sea, with incredibly effective venom which can be lethal to humans.
Little velvetfishes or simply velvetfishes are a family, the Aploactinidae, of scorpaeniform fishes.
Apistidae, the wasp scorpionfishes, is a family of scorpaeniform fishes native to the Indian Ocean and the western Pacific Ocean. They are fairly small fishes reaching lengths of 15 centimetres (5.9 in) TL in Cheroscorpaena tridactyla to 20 centimetres (7.9 in) TL in Apistus carinatus.
Venomous fish are species of fish which produce strong mixtures of toxins harmful to humans which they deliberately deliver by means of a bite, sting, or stab, resulting in an envenomation. As a contrast, poisonous fish also produce a strong toxin, but they do not bite, sting, or stab to deliver the toxin, instead being poisonous to eat because the human digestive system does not destroy the toxin they contain in their bodies. Venomous fish do not necessarily cause poisoning if they are eaten, as the digestive system often destroys the venom.
Synanceia nana is a species of venomous fish, regionally referred to as the Red Sea stonefish or Dwarf scorpionfish.
Although most species in the Red Sea pose no threat to humans, there are a few notable exceptions.
The waspfishes are a family, the Tetrarogidae, of scorpaeniform fishes native to the Indian Ocean and the West Pacific. They are closely related to the scorpionfishes. As their name suggests, waspfishes are often venomous; having poison glands on their spines. They are bottom-dwelling fish, living at depths to 300 metres (980 ft). They are small fish, from 2.5–23 cm (1–9 in) long with spiny fins. These creatures usually live in hiding places on the sea bottom.
Synanceia is a genus of fish of the family Synanceiidae, the stonefish, whose members are venomous, dangerous, and even fatal to humans. They are the most venomous fish known. They are found in the coastal regions of the Indo-Pacific.
Synanceia horrida, also known as the estuarine stonefish or regionally as simply stonefish, is a species of venomous fish of the family Synanceiidae. They are carnivorous ray-finned fish with venomous spines that lives on reef bottoms, camouflaged as a rock. They are one of the most venomous fish in the world, and are often included in private and public aquariums.
Coral reef fish are fish which live amongst or in close relation to coral reefs. Coral reefs form complex ecosystems with tremendous biodiversity. Among the myriad inhabitants, the fish stand out as colourful and interesting to watch. Hundreds of species can exist in a small area of a healthy reef, many of them hidden or well camouflaged. Reef fish have developed many ingenious specialisations adapted to survival on the reefs.
Inimicus is a genus of venomous fishes, closely related to the true stonefishes. This genus is a member of the family Synanceiidae of the ray-finned fish order Scorpaeniformes. These benthic fishes are found on sandy or silty substrates of lagoon and seaward reefs, in coastal regions of tropical oceans. The ten described species are collectively known by various common names, including ghoul, goblinfish, sea goblin, spiny devilfish, stinger, and stingfish).
Inimicus sinensis, also known as the spotted ghoul, Chinese stinger, spotted stingerfish, or spotted stonefish, is a member of the Inimicus genus of venomous fishes. It is a member of the Synanceiidae family of the Scorpaeniformes order of ray-finned fishes. These benthic fishes are found on sandy or silty substrates of lagoon and seaward reefs, in coastal regions of tropical oceans. Like all the other known species of Inimicus, I. sinensis is a demersal ambush predator. They are nocturnal, and often dig themselves partially into the sandy seabed during the day.
Inimicus filamentosus, also known as the filament-finned stinger, barred ghoul, two-stick stingfish, or devil scorpionfish, is a member of the Inimicus genus of venomous fishes. It is a member of the Synanceiidae family of the Scorpaeniformes order of ray-finned fishes. These benthic fishes are found on sandy or silty substrates of lagoon and seaward reefs, in coastal regions of tropical oceans. Like all the other known species of Inimicus, I. filamentosus is a demersal ambush predator. They are nocturnal, and often dig themselves partially into the sandy seabed during the day.
Perryena leucometopon, the Whitenose pigfish, is a scorpaeniform fish endemic to the Pacific Ocean around Australia where it is found on coral reefs. This species grows to a length of 16 centimetres (6.3 in) TL. This species is the only known member of its genus and in 2013 was split from the family Congiopodidae into its own family.
Eschmeyer nexus is a species of fish known only from the Pacific Ocean from near Fiji where it is found at depths of from 27 to 43 metres. It is a very small fish, growing to a length of 4.1 centimetres (1.6 in) SL. This species is the only known member of its family, the Eschmeyeridae, also termed cofishes, which was established by Mandritsa in 2001.
Scorpaenopsis diabolus, the false stonefish or the devil scorpionfish, is a carnivorous ray-finned fish in the order Scorpaeniformes, the scorpionfishes and flatheads. It has venomous spines and lives in the tropical Indian and Pacific Oceans. It is a bottom-dwelling predator that relies on its camouflage to catch passing prey.
