The streamlined spinefoot (''Siganus argenteus''), also known as the forktail rabbitfish, schooling rabbitfish or silver spinefoot, is a species of marine ray-finned fish, a rabbitfish belonging to the family

Siganidae Rabbitfishes or spinefoots are perciform fishes in the family Siganidae. The 29 species are in a single genus, ''Siganus''. In some now obsolete classifications, the species having prominent face stripes—colloquially called foxfaces– ...

. It is found in the

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

region.

Taxonomy

The streamlined spinefoot was first formally described in 1825 as ''Amphacanthus argenteus'' by the French naturalists

Jean René Constant Quoy Jean René Constant Quoy (10 November 1790 in Maillé, Vendée, Maillé – 4 July 1869 in Rochefort, Charente-Maritime, Rochefort) was a French naval surgeon, zoologist and anatomist. In 1806, he began his medical studies at the school of naval ...

and

Joseph Paul Gaimard Joseph Paul Gaimard (31 January 1793 – 10 December 1858) was a French naval surgeon and naturalist. Biography Gaimard was born at Saint-Zacharie on January 31, 1793. He studied medicine at the naval medical school in Toulon, subsequent ...

with the type locality given as Guam in the

Marianas The Mariana Islands (; also the Marianas; in Chamorro: ''Manislan Mariånas'') are a crescent-shaped archipelago comprising the summits of fifteen longitudinally oriented, mostly dormant volcanic mountains in the northwestern Pacific Ocean, betw ...

. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

''argenteus'' means "silvery", a reference to the silver colour of the cheeks and lower body.

Description

The streamlined spinefoot has a body which is oval, compressed, slender and

fusiform Fusiform means having a spindle-like shape that is wide in the middle and tapers at both ends. It is similar to the lemon-shape, but often implies a focal broadening of a structure that continues from one or both ends, such as an aneurysm on a b ...

, the body has a

standard length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish m ...

which is 2.4 to 3 times its depth. The small head does not have a steep dorsal profile byt has a pointed snout. The front nostril has a flap which extends past the rear nostril. There is a procumbent spine at the front of the dorsal fin which is enclosed in the skin of the nape. The dorsal fin contains 13 spines and 10 soft rays while the

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

has 7 spines and 9 soft rays. The caudal fin has a deep fork. This species attains a maximum total length of , although is more typical. The colous of this species are that blue on the upper body with a silvery lower body. They frequently have variable markings, spots and curved lines, particularly on the lower flanks. The eye has a silvery-yellow iris. The axil of pectoral fin is yellow and there is normally a yellow stripe along the base of the dorsal fin. There is also a dark brown bar on the upper edge of the operculum. This fish changes colour when alarmed or asleep to pale and dark brown mottling, with dark areas forming 7 diagonal zones across the flanks and the fins becoming mottled.

Distribution and habitat

The streamlined spinefoot has a wide Indo-Pacific distribution from the Red Sea south to Mozambique and Madagascar and east into the Pacific Ocean as far as Pitcairn Island, north to Japan and south to Australia. In Australia it is distributed from the area of

Shark Bay Shark Bay (Malgana: ''Gathaagudu'', "two waters") is a World Heritage Site in the Gascoyne region of Western Australia. The http://www.environment.gov.au/heritage/places/world/shark-bay area is located approximately north of Perth, on the ...

in Western Australia to the Ashmore Reef in the Timor Sea, and on the east coast from the northern Great Barrier Reef near Cape York south to Moreton Bay in Queensland, it also occurs on reefs in the

Coral Sea The Coral Sea () is a marginal sea of the South Pacific off the northeast coast of Australia, and classified as an interim Australian bioregion. The Coral Sea extends down the Australian northeast coast. Most of it is protected by the Fre ...

and at the Cocos (Keeling) Islands. It has been recorded once in the Mediterranean Sea off Libya but how this specimen reached there is uncertain. At remote islands such as Rapa, Pitcairn and the

Line Islands The Line Islands, Teraina Islands or Equatorial Islands (in Gilbertese, ''Aono Raina'') are a chain of 11 atolls (with partly or fully enclosed lagoons) and coral islands (with a surrounding reef) in the central Pacific Ocean, south of the Hawa ...

this species may be the only rabbitfish present. It occurs at depths down to in lagoons, on reefs, and in seaweed and seagrass beds.

Biology

The streamlined spinefoot is normally found in large, fast swimming schools on the water column clear of the seabed, every now and again they all dive down to the substrare to feed. Juveniles and adults may be encountered in small schools of 2–100 individuals near coral reefs, usually in the surge zone on the edge of the reef. Juveniles inhabit the water close to the surface in dense schools as far as several kilometres offshore, moving on to reef flats just before metamorphosis. The streamlined spinefoot has a diet made up of red and green

macroalgae Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of ''Rhodophyta'' (red), ''Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as k ...

and it is one of the few herbivorous fishes that is able to eat the chemically rich macroalgae ''

Chlorodesmis fastigata ''Chlorodesmis'' is a genus of green algae in the family Udoteaceae. Algae in this genus produce the toxic diterpene Diterpenes are a class of chemical compounds composed of four isoprene units, often with the molecular formula C20H32. They ...

'', however, this algae may only be eaten opportunistically and is likely a minor part of the total diet. They have spines which can inject venom into an attacker. Unusually for a rabbitfish, the streamlined spinefoot is a pelagic spawner and has a relatively long

larval A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The l ...

stage and a unique prejuvenile stage. These long developmental stages allow it to disperse widely and makes the species less vulnerable than its congeners to overfishing.

Fisheries

Streamlined spinefoot are frequently recorded in markets in parts of their range, both as juveniles and adults. The pre-juveniles are taken as they migrate to reef flat areas in a brief but important part of local fisheries, e.g. in Guam. They are consumed fresh, pickled in brine, or made into fish paste.

References

External links

* {{Taxonbar, from=Q1044087 Siganidae Fish of the Indian Ocean Fish of the Pacific Ocean Fish described in 1825 Taxa named by Jean René Constant Quoy Taxa named by Joseph Paul Gaimard