''Zu elongatus'', or the taper-tail ribbonfish, is a species of

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

within the family Trachipteridae. The species distribution is poorly known, and while it likely lives in temperate and tropical waters of all oceans, but has only been encountered in the

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 ...

- off the

coast A coast (coastline, shoreline, seashore) is the land next to the sea or the line that forms the boundary between the land and the ocean or a lake. Coasts are influenced by the topography of the surrounding landscape and by aquatic erosion, su ...

s of

Namibia Namibia, officially the Republic of Namibia, is a country on the west coast of Southern Africa. Its borders include the Atlantic Ocean to the west, Angola and Zambia to the north, Botswana to the east and South Africa to the south; in the no ...

and the western Cape of

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

- and in the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

off

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

. It inhabits

mesopelagic The mesopelagic zone (Greek language, Greek μέσον, middle), also known as the middle pelagic or twilight zone, is the part of the pelagic zone that lies between the photic epipelagic and the aphotic bathypelagic zones. It is defined by light ...

waters up to 1200 meters below sea level. Other

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often con ...

s for this species include "scalloped dealfish" and ''spitsstert-lintvis'' in

Afrikaans Afrikaans is a West Germanic languages, West Germanic language spoken in South Africa, Namibia and to a lesser extent Botswana, Zambia, Zimbabwe and also Argentina where there is a group in Sarmiento, Chubut, Sarmiento that speaks the Pat ...

Biology

''Zu elongatus'' grows to a length of 120 centimeters and has a silvery grey coloration with bars along the sides. The

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

s of adults are bright red. The dorsal fins lack spines but are composed of 142-147 soft rays. Juveniles are

epipelagic The photic zone (or euphotic zone, epipelagic zone, or sunlight zone) is the uppermost layer of a body of water that receives sunlight, allowing phytoplankton to perform photosynthesis. It undergoes a series of physical, chemical, and biological ...

, spending time near the surface, and have trailing, elongated

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage The fus ...

and pelvic fins that mimic

siphonophores Siphonophorae (from Ancient Greek σίφων (siphōn), meaning "tube" and -φόρος (-phóros), meaning "bearing") is an Order (biology), order within Hydrozoa, a class of marine organisms within the phylum Cnidaria. According to the World Re ...

and

jellyfish Jellyfish, also known as sea jellies or simply jellies, are the #Life cycle, 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 animal ...

. The diet of the species consists of

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s, small fish and

squid A squid (: squid) is a mollusc with an elongated soft body, large eyes, eight cephalopod limb, arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida (though many other molluscs within the broader Neocoleoidea are also ...

. Eggs of ''Zu elongatus'' are large and free floating with a bright red coloration. When preserved in alcohol, the bodies of adults are generally tan in color, with a dark triangular area on the front of the head that extends onto the lips and the gular area.Heemstra, P.C. and S.X. Kannemeyer, 1986. Trachipteridae. p. 399-402. In M.M. Smith and P.C. Heemstra (eds.) Smiths' sea fishes. Springer-Verlag, Berlin. The posterior part of the dorsal fin and caudal fin are black, to the base of the latter is pale.

Conservation

''Zu elongatus'' has been classified as a '

Least concern A least-concern species is a species that has been evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...

' species by the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological ...

, as despite having little information about its population and ecology, there are no major threats to any of its populations.

References

{{Taxonbar, from=Q959473 IUCN Red List least concern species Trachipteridae Fish described in 1984 Fish of the Atlantic Ocean Fish of the Pacific Ocean Fish of Namibia Marine fish of New Zealand Marine fish of South Africa