Chondrichthyes is a class of jawed fish that contains the cartilaginous fish or chondrichthyians, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or bony fish, which have skeletons primarily composed of bone tissue. Chondrichthyes are aquatic vertebrates with paired fins, paired nares, placoid scales, conus arteriosus in the heart, and a lack of opecula and swim bladders. Within the infraphylum Gnathostomata, cartilaginous fishes are distinct from all other jawed vertebrates.
Chimaeras are cartilaginous fish in the order Chimaeriformes, known informally as ghost sharks, rat fish, spookfish, or rabbit fish; the last three names are not to be confused with rattails, Opisthoproctidae, or Siganidae, respectively.
Lanternfish are small mesopelagic fish of the large family Myctophidae. One of two families in the order Myctophiformes, the Myctophidae are represented by 246 species in 33 genera, and are found in oceans worldwide. Lanternfishes are aptly named after their conspicuous use of bioluminescence. Their sister family, the Neoscopelidae, are much fewer in number but superficially very similar; at least one neoscopelid shares the common name "lanternfish": the large-scaled lantern fish, Neoscopelus macrolepidotus.
The prickly shark is one of the two species of sharks in the family Echinorhinidae, found in the Pacific Ocean over continental and insular shelves and slopes, and in submarine canyons. Bottom-dwelling in nature, it generally inhabits cool waters 100–650 m (330–2,130 ft) deep, but it also frequently enters shallower water in areas such as Monterey Bay off California. This stocky, dark-colored shark grows up to 4.0 m (13.1 ft) long, with two small dorsal fins positioned far back on its body and no anal fin. It is characterized by a dense covering of thorn-like dermal denticles, hence its common name.
The sharpnose sevengill shark, also known as one-finned shark, perlon shark, sevengill cow shark, sharpsnouted sevengill or slender sevengill, is a species of shark in the family Hexanchidae, and the only living species in the genus Heptranchias. Found almost circumglobally in deep water, it is one of the few species of sharks with seven pairs of gill slits as opposed to the usual five. The other shark species with seven gill slits is the broadnose sevengill shark. Though small, this shark is an active, voracious predator of invertebrates and fish. When caught, this species is notably defensive and will attempt to bite. It is of minor commercial importance.
The narrownose chimaera is a longnose chimaera of the family Rhinochimaeridae, the longnose chimaeras, consisting of eight species belonging three genera. This species is found in temperate seas worldwide, at depths between 200 and 3,100 m. Its length is between 1.0 and 1.5 m, including a long, tapering snout and a long, filamentous tail.
The bignose shark is a species of requiem shark, in the family Carcharhinidae. Distributed worldwide in tropical and subtropical waters, this migratory shark frequents deep waters around the edges of the continental shelf. It is typically found at depths of 90–430 m (300–1,410 ft), though at night it may move towards the surface or into shallower water. The bignose shark is plain-colored and grows to at least 2.7–2.8 m (8.9–9.2 ft) in length. It has a long, broad snout with prominent nasal skin flaps, and tall, triangular upper teeth. Its pectoral fins are long and almost straight, and there is a ridge on its back between the two dorsal fins.
The spotted eagle ray is a cartilaginous fish of the eagle ray family, Aetobatidae. As traditionally recognized, it is found globally in tropical regions, including the Atlantic, Pacific and Indian Oceans. Recent authorities have restricted it to the Atlantic with other populations recognized as the ocellated eagle ray and Pacific white-spotted eagle ray. Spotted eagle rays are most commonly seen alone, but occasionally swim in groups. They are ovoviviparous, the female retaining the eggs then releasing the young as miniature versions of the parent.
Callorhinchus, the plough-nosed chimaeras or elephantfish, are the only living genus in the family Callorhinchidae. A few extinct genera only known from fossil remains are recognized. Callorhinchus spp. are similar in form and habits to other chimaeras, but are distinguished by the presence of an elongated, flexible, fleshy snout, with a vague resemblance to a ploughshare. They are only found in the oceans of the Southern Hemisphere along the ocean bottom on muddy and sandy substrates. They filter feed, with small shellfish making up the bulk of their diet. The plough-nosed chimaera lays eggs on the ocean floor that hatch at around 8 months. They are currently not a target of conservation efforts; however, they may be susceptible to overfishing and trawling.
The smallspine spookfish is a species of fish in the family Rhinochimaeridae with a rather disjunct population. Its natural habitat is open seas.
Rhinochimaera is a genus of cartilaginous fish in the family Rhinochimaeridae, with these species:
The Chimaeridae, or short-nosed chimaeras, are a family of cartilaginous fish.
The Rhinochimaeridae, commonly known as long-nosed chimaeras, are a family of cartilaginous fish. They are similar in form and habits to other chimaeras, but have an exceptionally long conical or paddle-shaped snout. The snout has numerous sensory nerve endings, and is used to find food such as small fish. The first dorsal fin includes a mildly venomous spine, used in defense.
Chimaera is the type genus of the cartilaginous fish family Chimaeridae.
The large-eyed rabbitfish is a species of fish in the family Chimaeridae. It is found in several areas of the Atlantic Ocean and within the Mediterranean Sea.
Dolichopteryx is a genus of barreleyes.
Parotodus, commonly known as the false-toothed mako shark, is an extinct genus of mackerel shark that lived approximately 53 to one million years ago during the Eocene and Pleistocene epochs. Its teeth, which are found worldwide, are often prized by fossil collectors due to their rarity. The scarcity of fossils is because Parotodus likely primarily inhabited open oceans far away from the continents.
