The Hexanchiformes are a primitive order of sharks, numbering just seven extant species in two families. Fossil sharks that were apparently very similar to modern sevengill species are known from Jurassic specimens.
The Squaliformes are an order of sharks that includes about 126 species in seven families.
The gnomefishes form a small family, Scombropidae, consisting of three extant species of marine ray-finned fish in the genus Scombrops. They have two dorsal fins and are notable for scales covering the soft parts of the dorsal and anal fins. The eyes are large. The gnomefish, S. boops, lives in deep rocky areas, down to 400 m. It can grow to 150 cm total length and 16 kg weight.
The ricefishes are a family (Adrianichthyidae) of small ray-finned fish that are found in fresh and brackish waters from India to Japan and out into the Malay Archipelago, most notably Sulawesi. The common name ricefish derives from the fact that some species are found in rice paddies. This family consists of about 37 species in two genera. Several species are rare and threatened, and some 2–4 may already be extinct.
Squalidae, more commonly known as dogfish, dog sharks, or spiny dogfish, are one of several families of sharks categorized under Squaliformes, making it the second largest order of sharks, numbering 119 species across 7 families. Having earned their name after a group of fishermen reportedly observed the species chasing down smaller fish in dog-like packs, dogfish have slender, streamlined bodies, usually more compact in comparison to other species, and a pointed snout. Dogfish likewise have two dorsal fins, each with smooth spines, but no anal fin, and their skin is generally rough to the touch. As the species reaches adulthood, males usually measure a maximum of 100 cm, while females typically measure 125 cm long. The species therefore exhibits female-dominant sexual dimorphism.
The guitarfish, also referred to as shovelnose rays, are a family, Rhinobatidae, of rays. The guitarfish are known for an elongated body with a flattened head and trunk and small, ray-like wings. The combined range of the various species is tropical, subtropical, and warm temperate waters worldwide.
Rajiformes is one of the four orders in the clade Batomorphi, often referred to as the superorder Batoidea, flattened cartilaginous fishes related to sharks. Rajiforms are distinguished by the presence of greatly enlarged pectoral fins, which reach as far forward as the sides of the head, with a generally flattened body. The undulatory pectoral fin motion diagnostic to this taxon is known as rajiform locomotion. The eyes and spiracles are located on the upper surface of the head and the gill slits are on the underside of the body. Most species give birth to live young, although some lay eggs enclosed in a horny capsule.
The bramble shark is one of the two species of sharks in the family Echinorhinidae. Aside from the eastern Pacific Ocean, it is found in tropical and temperate waters worldwide. This rarely encountered shark swims close to the bottom of the seafloor, typically at depths of 400–900 m (1,300–3,000 ft), though it may enter much shallower water. The bramble shark has a stout body with two small dorsal fins positioned far back and no anal fin. It can be readily identified by the large, thornlike dermal denticles scattered over its body, some of which may be fused together. It is purplish brown or black in color and grows up to 3.1 m (10 ft) long.
Stylephorus chordatus, the tube-eye or thread-tail, is a deep-sea ray-finned fish, the only species in the genus Stylephorus and family Stylephoridae.
The barred fingerfin is a species of marine ray-finned fish, belonging to the family Cheilodactylidae, commonly referred to as morwongs. It is found only in the southeastern Atlantic and southwestern Indian Oceans off the coasts of South Africa.
The onefin catshark is a species of shark belonging to the family Pentanchidae, the deepwater catsharks. It is the only member of its genus, Pentanchus. It is known from two specimens collected from the Tablas Strait and Mindanao Sea off the Philippines in the Western Central Pacific. It is classified as harmless to humans and of least concern to the IUCN redlist.
The rasptooth dogfish is a dogfish, found on the Kyushu–Palau Ridge in the northwest Pacific Ocean at depths of 360 m. Its maximum length is unknown. This species was originally described as Centroscyllium sheikoi, and subsequently allocated to the newly named genus Miroscyllium based on anatomical features not shared with other Centroscyllium. More recent molecular data suggest this species belongs to the genus Etmopterus, but as of June 2014 Miroscyllium sheikoi remains the valid name recognized by FishBase, the Catalog of Fishes World Register of Marine Species, and the IUCN
The viper dogfish or viper shark is a rare species of dogfish shark in the family Etmopteridae, and the only extant member of its genus. It has been found in the Pacific Ocean off southern Japan, the Bonin Islands, Pacific Ocean off northern Taitung County and the Northwestern Hawaiian Islands. This species inhabits upper continental slopes and seamounts. It may migrate vertically, shifting between bottom waters 270–360 m (890–1,180 ft) deep during the day and upper waters less than 150 m (490 ft) deep at night. A slender, black shark reaching 54 cm (21 in) in length, the viper dogfish can be recognized by its narrow, triangular jaws and well-spaced, fang-like teeth. It also has two spined dorsal fins, dermal denticles with faceted crowns, and numerous light-emitting photophores concentrated on its ventral surface.
Etmopterus is a genus of lantern sharks in the squaliform family Etmopteridae. They are found in deep sea ecosystems of the Atlantic, Indian and Pacific Oceans.
Bahaba is a genus of marine ray-finned fishes belonging to the family Sciaenidae, the drums and croakers. These fishes are found in the Indo-West Pacific region.
Fish are very diverse animals and can be categorised in many ways. Although most fish species have probably been discovered and described, about 250 new ones are still discovered every year. According to FishBase about 34,800 species of fish had been described as of February 2022, which is more than the combined total of all other vertebrate species: mammals, amphibians, reptiles and birds.
Ereunias is a monotypic genus of marine ray-finned fish belonging to the family Rhamphocottidae, the grunt sculpins. Its only species is Ereunias grallator which is a bathydemersal species found at depths of around 500 m (1,600 ft) in the northwestern Pacific Ocean off Japan. This species attains a maximum published total length of 30 cm (12 in). This species was first formally described in 1901 by the American ichthyologists David Starr Jordan and John Otterbein Snyder from Misaki, Sagami in Japan. Jordan and Snyder proposed the new genus Ereunias for the new species. The genus name is derived from ereunao, meaning "to explore" which may refer how it uses elongated pectoral-fin rays as feelers or “feet” to explore the substrate; suffixed with ias which is used in some Greek names for fishes. The specific name grallator is "stiltwalker" in Latin and is an allusion to the elongated pectoral fin rays. Along with the genus Marukawichthys this taxon was classified in the family Ereunidae but this was synonymised with the Rhamphocottidae in 2014.
Squalomorphi is a superorder of cartilaginous fishes, generally characterized by lacking traits such as an anal fin, nictitating membrane, or suborbital shelves in the cranium. Squalomorphii sharks are also called squalea, or squalean sharks. There are about 163 living species in 11 families. Squalean sharks are divided into four orders: the Hexanchiformes, Squaliformes, Squatiniformes, and Pristiophoriformes.
Rhinopristiformes is an order of rays, cartilaginous fishes related to sharks, containing shovelnose rays and allied groups.
