The bullhead sharks are members of the genus Heterodontus, the only members of the family Heterodontidae and only living members of the order Heterodontiformes. All are relatively small, with the largest species reaching just 1.65 metres (5.5 ft) in maximum length. They are bottom feeders in tropical and subtropical waters.
Skates are cartilaginous fish belonging to the family Rajidae in the superorder Batoidea of rays. More than 150 species have been described, in 17 genera. Softnose skates and pygmy skates were previously treated as subfamilies of Rajidae, but are now considered as distinct families. Alternatively, the name "skate" is used to refer to the entire order of Rajiformes.
In animals, viviparity is development of the embryo inside the body of the mother, with the maternal circulation providing for the metabolic needs of the embryo's development, until the mother gives birth to a fully or partially developed juvenile that is at least metabolically independent. This is opposed to oviparity, where the embryos develop independently outside the mother in eggs until they are developed enough to break out as hatchlings; and ovoviviparity, where the embryos are developed in eggs that remain carried inside the mother's body until the hatchlings emerge from the mother as juveniles, similar to a live birth.
Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop inside eggs that remain in the mother's body until they are ready to hatch.
An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the animal hatches.
Fish reproductive organs include testes and ovaries. In most species, gonads are paired organs of similar size, which can be partially or totally fused. There may also be a range of secondary organs that increase reproductive fitness. The genital papilla is a small, fleshy tube behind the anus in some fishes, from which the sperm or eggs are released; the sex of a fish can often be determined by the shape of its papilla.
Oviparous animals are animals that reproduce by depositing fertilized zygotes outside the body in metabolically independent incubation organs known as eggs, which nurture the embryo into moving offsprings known as hatchlings with little or no embryonic development within the mother. This is the reproductive method used by most animal species, as opposed to viviparous animals that develop the embryos internally and metabolically dependent on the maternal circulation, until the mother gives birth to live juveniles.
The swell shark is a catshark in the family Scyliorhinidae. It is found in the tropical and subtropical eastern Pacific Ocean from between central California to southern Mexico, with an additional population off the coast of Chile. As a defense, the swell shark is able to expand to approximately double its regular size by swallowing water.
The redspotted catshark, also known as the Chilean catshark, is a species of catshark commonly found in the coastal waters of the southeastern Pacific, from central Peru to southern Chile. They are typically found in the rocky sublittoral areas at the edge of the continental shelf, in waters down to 100 m in depth. They spend the spring, summer, and fall in rocky subtidal areas, but winter in deeper offshore waters due to the strong currents at that time of year.
The finback catsharks are a small family, the Proscylliidae, of ground sharks. They can be found in warm seas worldwide and are often the most numerous and common shark in tropical regions. They are generally less than 1 m in length, and are slow-moving predators that feed on bony fish and small invertebrates. Although some bear live young, the majority lay eggs with almost fully developed young; these egg cases, known as "mermaid's purses", are unique in appearance to each species.
The draughtsboard shark is a species of catshark, and part of the family Scyliorhinidae, so named for its "checkerboard" colour pattern of dark blotches. It is endemic to New Zealand, where it is also known as the carpet shark. This shark typically reaches 1 m (3.3 ft) in length and has a thick body with a broad, flattened head and a capacious mouth. Its two dorsal fins are placed far back on the body, with the first much larger than the second.
The brown shyshark or plain happy is a species of shark belonging to the family Pentanchidae, the deepwater catsharks. It is endemic to the shallow, coastal waters of South Africa from west of Cape Agulhas to KwaZulu-Natal. This benthic species is usually found over sandy or rocky bottoms. Measuring up to 73 cm (29 in) long, the brown shyshark is stoutly built, with a broad, flattened head and rounded snout. Unlike other shysharks, the brown shyshark has a plain brown color, though some individuals have faint "saddle" markings or light or dark spots. When threatened, this shark curls into a circle with its tail over its eyes, which is the origin of the name "shyshark". It feeds on bony fishes and lobsters, and is oviparous with females laying pairs of egg capsules. The International Union for Conservation of Nature (IUCN) has assessed this harmless species as Vulnerable. It is of no commercial or recreational interest, but its limited distribution makes its entire population vulnerable to increases in fishing pressure or habitat degradation.
The dusky catshark is a species of shark belonging to the family Pentanchidae, the deepwater catsharks. This shark is endemic to the southeast Pacific Ocean, off the coasts of Peru and Chile. It grows to a maximum length of 70 cm (28 in), and is oviparous like many other chondrichthyans in the Indo-Pacific.
The cloudy catshark is a common species of catshark, belonging to the family Scyliorhinidae. It is a bottom-dweller that inhabits rocky reefs in the northwestern Pacific Ocean, from the shore to a depth of 320 m (1,050 ft). Growing up to 50 cm (20 in) long, this small, slim shark has a narrow head with a short blunt snout, no grooves between the nostrils and mouth, and furrows on the lower but not the upper jaw. It is also characterized by extremely rough skin and coloration consisting of a series of dark brown saddles along its back and tail, along with various darker and lighter spots in larger individuals.
The small-spotted catshark, also known as the sandy dogfish, lesser-spotted dogfish, rough-hound or morgay, is a catshark of the family Scyliorhinidae. It is found on the continental shelves and the uppermost continental slopes off the coasts of Norway and the British Isles south to Senegal and in the Mediterranean, between latitudes 63° N and 12° N. It can grow up to a length of 1 m, and it can weigh more than 2 kg (4.4 lb). It is found primarily over sandy, gravelly, or muddy bottoms from depths of a few metres down to 400 m (1,300 ft). S. canicula is one of the most abundant elasmobranchs in the northeast Atlantic and Mediterranean Sea. The majority of the populations are stable in most areas.
The mouse catshark is a species of shark belonging to the family Pentanchidae, the deepwater catsharks. It is common in the northeastern Atlantic Ocean from Iceland to Western Sahara. There is much taxonomic confusion regarding this species in Icelandic waters, where it may be confounded with another species of Galeus or Apristurus. Probably not exceeding 49 cm (19 in) long, the mouse catshark has a uniformly brown body and is characterized by large, rounded pelvic fins and crests of enlarged dermal denticles along both the dorsal and ventral caudal fin margins. In addition, in adult males the inner margins of the pelvic fins are merged into an "apron".
The big skate is the largest species of skate in the waters off North America. They are found along the Pacific Coast from Alaska to Baja California, typically from the intertidal zone to a depth of 120 m (390 ft), and feed on benthic invertebrates and small fishes. They are unusual among skates in that their egg cases may contain up to seven eggs each. This species is one of the most commercially important skates off California and is sold for food.
The mottled skate is a species of skate in the family Rajidae. An inhabitant of shallow coastal waters, it is found in the northwestern Pacific Ocean off Korea, Japan, and China. This species grows to 1.12 m (3.7 ft) long and has a diamond-shaped pectoral fin disc with a long snout. It is characterized by a covering of prickles above and below its snout, but not elsewhere on its body, and a dark ring in the middle of each "wing".
The clearnose skate is a species of cartilaginous fish in the family Rajidae. R. eglanteria is also known by other common names such as the brier skate and summer skate. Clearnose skates are easily identified by the translucent patches on either side of their snouts and their mottled dorsal surface. They are found along the Atlantic and Gulf coasts of the United States in shallow waters of the continental shelf.
The Sarawak pygmy swellshark is a species of catshark, belonging to the family Scyliorhinidae. It is found in the benthic zone near the edge of the Pacific continental shelf, at depths of 118–165 m.
