A seamount is a large submarine landform that rises from the ocean floor without reaching the water surface, and thus is not an island, islet, or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly and are usually found rising from the seafloor to 1,000–4,000 m (3,300–13,100 ft) in height. They are defined by oceanographers as independent features that rise to at least 1,000 m (3,281 ft) above the seafloor, characteristically of conical form. The peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the deep sea. During their evolution over geologic time, the largest seamounts may reach the sea surface where wave action erodes the summit to form a flat surface. After they have subsided and sunk below the sea surface such flat-top seamounts are called "guyots" or "tablemounts".
The New Zealand catshark is a catshark of the family Scyliorhinidae in the order Carcharhiniformes. This species is endemic to in the deep waters around New Zealand. Its length is up to 45 centimetres (18 in). The New Zealand catshark is a small, little-known deep water bottom shark. It is dark brown around the top with a few widely spaced pale spots, and white below. It feeds on bottom-living crustaceans. It is also completely harmless to humans.
Galeus is a genus of catshark, belonging to the family Scyliorhinidae, commonly known as sawtail catsharks in reference to a distinctive saw-toothed crest of enlarged dermal denticles, found along the upper edges of their caudal fins. They are found in the Atlantic, the western and central Pacific, and the Gulf of California, inhabiting deep waters at or close to the sea floor. Members of this genus are rather small, slim sharks with firm bodies and thick, rough skin. Their heads are usually fairly long and pointed, and have large mouths with well-developed furrows at the corners. They have large pectoral and anal fins, and two similar dorsal fins placed well back. Many species are ornately patterned with dark saddles and/or blotches. Sawtail catsharks feed on various invertebrates and fishes, and may be either egg-laying or live-bearing. These harmless sharks are sometimes caught as bycatch but are of minimal commercial value.
The white-spotted Izak or African spotted catshark is a catshark of the family Scyliorhinidae. It is found in the western Indian Ocean off the coasts of Natal, South Africa, southern Mozambique, Madagascar, Kenya, and Tanzania between latitudes 4° S and 37° S, at depths of between 220 and 440 m. It can grow up to 35 cm in length.
The smooth lanternshark or slender lanternshark is a species of dogfish shark in the family Etmopteridae, found widely in the Atlantic and Pacific Oceans. It inhabits benthic environments at a depth of 274–1,000 m (899–3,281 ft), and pelagic environments at a depth of 0–708 m (0–2,323 ft). The smooth lanternshark forms a species group with the larger blurred lanternshark, both of which are distinguished from other members of their family by small, irregularly arranged dermal denticles with a truncated shape. This species has a slender, dark brown body with an indistinct black band on the sides over the pelvic fins, and reaches 50 cm (20 in) in length. This slow-growing, ovoviviparous shark feeds on smaller squid, fishes, and fish eggs. Smooth lanternsharks are often caught as bycatch in eastern Atlantic and Japanese commercial fisheries. The International Union for Conservation of Nature (IUCN) has evaluated this species as of Least Concern because of its wide distribution and limited threats.
The Arabian catshark is a catshark of the family Scyliorhinidae. It can grow up to 30 centimetres (12 in) long, and lives in open seas. It is only known from a single specimen, now lost, which was found on the continental slope of the Arabian Sea.
The spotless catshark is a catshark of the family Scyliorhinidae found in the South China Sea at depths between 535 and 1,020 m on the continental slope. Its length is up to 71 centimetres (28 in).
The bristly catshark is a cat shark of the family Scyliorhinidae, found from southeastern India and the Andaman Islands, between latitudes 15° N and 5° N, at depths between 200 and 300 m. Its length usually ranges from around 20–26 cm, and it is regarded as the smallest catshark of Bythaelurus.
The dusky catshark is a catshark of the family Scyliorhinidae that is endemic to the southeast Pacific Ocean, off the coasts of Peru and Chile. It grows to a maximum length of 70 cm, and is oviparous like many other chondrichthyans in the Indo-Pacific.
The blackspotted catshark is a catshark of the family Scyliorhinidae. It is found in the waters off the coasts of Japan, Korea, China, and Taiwan between latitudes 39° N and 20° N, at the depths of between 80 and 100 m. It can grow up to 49 cm in length.
The spongehead catshark is a rare species of deep-sea catshark, family Scyliorhinidae. This species was only known from two specimens taken in the Pacific Ocean: an adult from near Bird Island, Hawaii, and a juvenile from the Banda Sea off Sulawesi. They are found on or near the bottoms of insular continental slopes, at depths of 570 to 1,480 meters. In 2002, the spongehead catshark was seen alive in its natural habitat for the first time, from the submersible Pisces IV at a depth of about a kilometer, on the Northampton Seamount off the northwestern Hawaiian Islands.
Bythaelurus is a genus of deep-water catsharks and part of the family Scyliorhinidae. The genus Bythaelurus Compagno 1988 was first described as a subgenus of Halaelurus Gill 1862 based on several morphological characteristics including a soft body with thin skin, a bluntly rounded snout without a pointed, knob-like tip, and eyes not noticeably elevated on the dorsal surface of the head. Members of this genus are generally found in deep water and have more somber body coloration.
The mud catshark or brown catshark is a species of catshark in the family Scyliorhinidae. It is found in Mozambique and Somalia. Its natural habitat is the open seas of the western Indian Ocean, from Mozambique to Somalia, between latitudes 13° N and 29° S, at depths between 340 and 765 m. It can grow up to 34 centimetres (13 in) long.
The sombre catshark is a species of catshark in the family Scyliorhinidae. It is known from a single specimen south of Rote Island, northwestern Australia. Its natural habitat is the open seas.
The jaguar catshark, also known as the Galápagos catshark, is a species of catshark from the Galápagos Islands. The species was first described in 2012. This catshark is about a foot long when mature, and it is colored blackish-brown with an asymmetrical pattern of light spots.
The dusky snout catshark is a catshark of the family Scyliorhinidae. This species is found from the Southwest Indian Ridge, southwestern Indian Ocean. The specimens were collected from 89–1,443 m depth in both bottom trawls and midwater trawls. The shallowest catch record of the new species, possibly at 89 m, came from a midwater trawl. This species can be distinguished from its two closest congeners, B. giddingsi and B. lutarius, by a combination of prominent comb-like dermal denticles along the upper caudal-fin margin, absence of oral papillae, uniform body coloration, and noticeable dark dusky snout; Bythaelurus giddingsi has oral papillae present and a variegated color pattern, while B. lutarius lacks a caudal crest of enlarged denticles and matures at a much smaller size than the new species.
The narrowhead catshark is a catshark of the family Scyliorhinidae. This species is described based on one adult and one juvenile male specimen from off Tanzania and Mozambique in the western Indian Ocean. The species differs from its congeners by its slender head and snout, which is only slightly bell-shaped in dorsoventral view without distinct lateral indention. It further differs from B. clevai by attaining a smaller maximum size and having a color pattern of fewer and smaller blotches, larger oral papillae, a shorter snout, and broader claspers without knob-like apex and with a smaller envelope and a subtriangular exorhipidion. Compared to B. hispidus, the species has a longer snout, a longer dorsal-caudal space, broader clasper without knob-like apex, and fewer vertebral centra. In contrast to B. lutarius, B. tenuicephalus attains a smaller size and has a blotched coloration, numerous oral papillae, shorter anterior nasal flaps, a longer caudal fin, a shorter pelvic anal space, and shorter and broader claspers.
Bythaelurus bachi, commonly known as Bach's catshark, is a species of catshark found in southern Madagascar Ridge in the southwestern Indian Ocean. This stout-bodied catshark is thought to inhabit the deep sea at depths of 910–1,365 m (2,986–4,478 ft).
Bythaelurus vivaldii, Vivaldi's catshark, is a species of catshark found in Northwestern Indian Ocean, specifically in Somalia. It presumably lives in the depths of up to 628 m (2,060 ft).
