The black ruff (''Centrolophus niger'') is a

medusafish Medusafishes are a family, Centrolophidae, of scombriform ray-finned fishes. The family includes about 31 species. They are found in temperate and tropical waters throughout the world. Young '' Icichthys lockingtoni'' specimens are abundant in ...

, the only member of the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''Centrolophus''. It is a

pelagic fish Pelagic fish live in the pelagic zone of ocean or lake waters—being neither close to the bottom nor near the shore—in contrast with demersal fish that live on or near the bottom, and reef fish that are associated with coral reefs. ...

found in all tropical and

temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...

oceans at depths of . Its length is typically up to , but it may reach . Other common names include rudderfish and blackfish.

Description

The black ruff has a robust

fusiform Fusiform (from Latin ''fusus'' ‘spindle’) means having a spindle (textiles), spindle-like shape that is wide in the middle and tapers at both ends. It is similar to the lemon (geometry), lemon-shape, but often implies a focal broadening of a ...

body shape and can grow to a length . The

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

has five spines and 37 to 41

soft rays Fish anatomy is the study of the form or morphology of fish. It can be contrasted with fish physiology, which is the study of how the component parts of fish function together in the living fish. In practice, fish anatomy and fish physiology co ...

, the

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

has three spines and 20 to 24 soft rays. The bases of these fins have a fleshy sheath clad with scales that partially conceals the rays. The head is grey and the body colour violet-black, dark brown or purplish, with a paler belly. The fins are darker than the body colour. Sometimes there are indistinct spots or a marbled pattern. The

otoliths An otolith (, ' ear + , ', a stone), also called otoconium, statolith, or statoconium, is a calcium carbonate structure in the saccule or utricle of the inner ear, specifically in the vestibular system of vertebrates. The saccule and utricle, i ...

of black ruff are thin and delicate, and about 15 mm in length for a 40 cm fish.

Distribution and habitat

The black ruff is known from the northwestern

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

, where its range extends from Nova Scotia to Massachusetts, the northeastern Atlantic and the Mediterranean Sea; also from the southeastern Atlantic and the

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...

, its range including South Africa and Australia and New Zealand, as well as the Southern Ocean. It is a pelagic fish, and has been caught at a wide range of depths, from close to the ocean surface to over 1000 m. It is largely absent from the tropics. It is occasionally found in the waters around the British Isles, where it has been recorded off

County Galway County Galway ( ; ) is a Counties of Ireland, county in Republic of Ireland, Ireland. It is in the Northern and Western Region, taking up the south of the Provinces of Ireland, province of Connacht. The county population was 276,451 at the 20 ...

County Donegal County Donegal ( ; ) is a Counties of Ireland, county of the Republic of Ireland. It is in the Provinces of Ireland, province of Ulster and is the northernmost county of Ireland. The county mostly borders Northern Ireland, sharing only a small b ...

and the

Isles of Scilly The Isles of Scilly ( ; ) are a small archipelago off the southwestern tip of Cornwall, England. One of the islands, St Agnes, Isles of Scilly, St Agnes, is over farther south than the most southerly point of the Great Britain, British mainla ...

. In 1901, a specimen was caught in a salmon net in the

Firth of Forth The Firth of Forth () is a firth in Scotland, an inlet of the North Sea that separates Fife to its north and Lothian to its south. Further inland, it becomes the estuary of the River Forth and several other rivers. Name ''Firth'' is a cognate ...

and was presented to the

Edinburgh Museum Edinburgh is the capital city of Scotland and one of its 32 council areas. The city is located in southeast Scotland and is bounded to the north by the Firth of Forth and to the south by the Pentland Hills. Edinburgh had a population of in , ...

Ecology

Juvenile fish are believed to live in surface waters but adults live at greater depths where they may form small schools. Black ruff is a generalist feeder, preying on any available organisms of suitable size that are present. Prey items include small fish,crustaceans such as

copepods Copepods (; meaning 'oar-feet') are a group of small crustaceans found in nearly every freshwater and saltwater habitat. Some species are planktonic (living in the water column), some are benthic (living on the sediments), several species have ...

and

amphipods Amphipoda () is an order (biology), order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods () range in size from and are mostly detritivores or scavengers. There are more than 10,700 amphip ...

, squid,

medusae Jellyfish, also known as sea jellies or simply jellies, are the medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals, althoug ...

and

ctenophores Ctenophora (; : ctenophore ) is a phylum of marine invertebrates, commonly known as comb jellies, that marine habitats, inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming (commonly referred to as "combs ...

References

* * Tony Ayling & Geoffrey Cox, ''Collins Guide to the Sea Fishes of New Zealand'', (William Collins Publishers Ltd, Auckland, New Zealand 1982) {{Taxonbar, from=Q2000476 Centrolophidae Fish of Hawaii Fish of the Atlantic Ocean Fish of the Indian Ocean Monotypic fish genera Fish described in 1789