Club-foot whiting
Encyclopedia
The club-foot whiting, Sillago chondropus, (also known as the Horrelvoet sillago) is a coastal marine
fish
of the smelt whiting family Sillaginidae
that inhabits a wide range including west Africa
, India
and the northern Indonesia
n Archipelago. The species is unique in the morphology of the pelvic spine and fin, making identification of the species easier than most of its relatives. The species is of minor commercial importance, taken by seine net and market
ed fresh throughout its range.
, which is one of three divisions of the smelt whiting family Sillaginidae
. The smelt-whitings are Perciformes
in the suborder Percoidea
. The anatomy of the species was distinct enough for McKay to assign S. chondropus to its own monotypic
subgenus
Sillaginopodys, which was one of three subgenera erected during a comprehensive review of the Sillaginidae in 1985.
The club-foot whiting was first described and named by Pieter Bleeker
in 1949, however the exact origin of the holotype
specimen
is unknown. Bleeker conducted most of his studies on the fishes of South East Asia, and one author has attributed the type specimen to samples collected from the Java Sea
. The common name of the species, club-foot whiting, is derived from its unique pelvic fin structure which may look, and possibly act as club shaped 'foot'. The other common name; Horrelvoet sillago, is a name used in Africa
and is derived from Afrikaans
.
, the club-foot whiting has a slightly compressed, elongate body tapering toward the terminal mouth
, with the species reaching a maximum overall length of 35cm. The body is covered in small ctenoid scales
extending to the cheek and head, which has scales arranged in 3-4 rows. The first dorsal fin
has 11 to 12 spines and the second dorsal fin has 1 leading spine with 20 to 22 soft rays posterior. The anal fin has 2 spines with 22 to 23 soft rays posterior to the spines. Possibly the most obvious identifying feature of the species is the characteristic pelvic fin, of which the first ray is modified into a laterally compressed club-like structure that overlaps the much reduced ventral spine at the base of the fin. Other distinguishing features include 66 to 73 lateral line
scales and a total of 35 vertebrae.
The swim bladder morphology is also very distinct in the Club-foot whiting, with a structure very different from the rest of the Sillago
. It is a very flat, non functional structure that sits just behind the axis vertebra and abruptly narrows to a fine point terminating at the 9th abdominal
vertebrae. The organ has no duct
like process stemming from the ventral surface unlike other species of Sillago.
The club-foot whiting is pale sandy brown colour above, with a paler underside and dusky scale margins. A dull silver
grey mid-lateral band is usually present, normally with an accompanying wide dusky band below on the lower sides. The fins are hyaline
in colour, with only the spinous first dorsal fin having a light dusting of fine black spots at the tip.
, northward along the west Africa
n coast to Pakistan
, India
, Myanmar
, Indonesia
, northern New Guinea
, Thailand
, Philippines
and Taiwan
. It has never recorded from southern New Guinea or Australia
. The species inhabits shallow coastal waters, from depths of 0 to 5 m. In eastern Taiwan, blackish substrates
with a strong current and wave action are inhabited, while in India it has been known to enter estuaries. The reduced swim bladder and modified pelvic fin indicates that this species is demersal and may use the pelvic fin pads somewhat like sled runners on the substrate.
s alongside other species of sillaginid. Small subsidence fisheries in India are known to take substantial amounts of the species as well.
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
of the smelt whiting family Sillaginidae
Sillaginidae
The Sillaginidae, commonly known as the smelt-whitings, whitings, sillaginids, sand borers and sand-smelts, are a family of benthic coastal marine fishes in the order Perciformes. The smelt-whitings inhabit a wide region covering much of the Indo-Pacific, from the west coast of Africa east to Japan...
that inhabits a wide range including west Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
and the northern Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
n Archipelago. The species is unique in the morphology of the pelvic spine and fin, making identification of the species easier than most of its relatives. The species is of minor commercial importance, taken by seine net and market
Market
A market is one of many varieties of systems, institutions, procedures, social relations and infrastructures whereby parties engage in exchange. While parties may exchange goods and services by barter, most markets rely on sellers offering their goods or services in exchange for money from buyers...
ed fresh throughout its range.
Taxonomy and naming
The club-foot whiting is one of 29 species in the genus SillagoSillago
Sillago is one of three genera in the family Sillaginidae containing the smelt-whitings, and contains 29 species, making Sillago the only non-monotypic genus in the family. Distinguishing among Sillago species can be difficult, with many similar in appearance and colour, forcing the use of swim...
, which is one of three divisions of the smelt whiting family Sillaginidae
Sillaginidae
The Sillaginidae, commonly known as the smelt-whitings, whitings, sillaginids, sand borers and sand-smelts, are a family of benthic coastal marine fishes in the order Perciformes. The smelt-whitings inhabit a wide region covering much of the Indo-Pacific, from the west coast of Africa east to Japan...
. The smelt-whitings are Perciformes
Perciformes
The Perciformes, also called the Percomorphi or Acanthopteri, is one of the largest orders of vertebrates, containing about 40% of all bony fish. Perciformes means perch-like. They belong to the class of ray-finned fish and comprise over 7,000 species found in almost all aquatic environments...
in the suborder Percoidea
Percoidea
Percoidea is a superfamily of fish of the order Perciformes....
. The anatomy of the species was distinct enough for McKay to assign S. chondropus to its own monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
subgenus
Subgenus
In biology, a subgenus is a taxonomic rank directly below genus.In zoology, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the generic name and the specific epithet: e.g. the Tiger Cowry of the Indo-Pacific, Cypraea tigris Linnaeus, which...
Sillaginopodys, which was one of three subgenera erected during a comprehensive review of the Sillaginidae in 1985.
The club-foot whiting was first described and named by Pieter Bleeker
Pieter Bleeker
Pieter Bleeker was a Dutch medical doctor and ichthyologist, famous for his work on the fishes of East Asia – Atlas Ichthyologique des Orientales Neerlandaises – which was published 1862–1877....
in 1949, however the exact origin of the holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
specimen
Specimen
A specimen is a portion/quantity of material for use in testing, examination, or study.BiologyA laboratory specimen is an individual animal, part of an animal, a plant, part of a plant, or a microorganism, used as a representative to study the properties of the whole population of that species or...
is unknown. Bleeker conducted most of his studies on the fishes of South East Asia, and one author has attributed the type specimen to samples collected from the Java Sea
Java Sea
The Java Sea is a large shallow sea on the Sunda Shelf. It was formed as sea levels rose at the end of the last ice age. The Java Sea lies between the Indonesian islands of Borneo to the north, Java to the south; Sumatra to the west, and Sulawesi to the east...
. The common name of the species, club-foot whiting, is derived from its unique pelvic fin structure which may look, and possibly act as club shaped 'foot'. The other common name; Horrelvoet sillago, is a name used in Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
and is derived from Afrikaans
Afrikaans
Afrikaans is a West Germanic language, spoken natively in South Africa and Namibia. It is a daughter language of Dutch, originating in its 17th century dialects, collectively referred to as Cape Dutch .Afrikaans is a daughter language of Dutch; see , , , , , .Afrikaans was historically called Cape...
.
Description
As with most of the genus SillagoSillago
Sillago is one of three genera in the family Sillaginidae containing the smelt-whitings, and contains 29 species, making Sillago the only non-monotypic genus in the family. Distinguishing among Sillago species can be difficult, with many similar in appearance and colour, forcing the use of swim...
, the club-foot whiting has a slightly compressed, elongate body tapering toward the terminal mouth
Mouth
The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....
, with the species reaching a maximum overall length of 35cm. The body is covered in small ctenoid scales
Scale (zoology)
In most biological nomenclature, a scale is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopteran species, scales are plates on the surface of the insect wing, and provide coloration...
extending to the cheek and head, which has scales arranged in 3-4 rows. The first dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
has 11 to 12 spines and the second dorsal fin has 1 leading spine with 20 to 22 soft rays posterior. The anal fin has 2 spines with 22 to 23 soft rays posterior to the spines. Possibly the most obvious identifying feature of the species is the characteristic pelvic fin, of which the first ray is modified into a laterally compressed club-like structure that overlaps the much reduced ventral spine at the base of the fin. Other distinguishing features include 66 to 73 lateral line
Lateral line
The lateral line is a sense organ in aquatic organisms , used to detect movement and vibration in the surrounding water. Lateral lines are usually visible as faint lines running lengthwise down each side, from the vicinity of the gill covers to the base of the tail...
scales and a total of 35 vertebrae.
The swim bladder morphology is also very distinct in the Club-foot whiting, with a structure very different from the rest of the Sillago
Sillago
Sillago is one of three genera in the family Sillaginidae containing the smelt-whitings, and contains 29 species, making Sillago the only non-monotypic genus in the family. Distinguishing among Sillago species can be difficult, with many similar in appearance and colour, forcing the use of swim...
. It is a very flat, non functional structure that sits just behind the axis vertebra and abruptly narrows to a fine point terminating at the 9th abdominal
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
vertebrae. The organ has no duct
Duct
A duct may refer to:* Duct , various ducts in anatomy and physiology* Duct , for transfer of air between spaces in a structure* Duct tape, a kind of adhesive tape* Ducted fan, motor for aircraft...
like process stemming from the ventral surface unlike other species of Sillago.
The club-foot whiting is pale sandy brown colour above, with a paler underside and dusky scale margins. A dull silver
Silver (color)
Silver is the metallic shade resembling gray, closest to that of polished silver.The visual sensation usually associated with the metal silver is its metallic shine. This cannot be reproduced by a simple solid color, because the shiny effect is due to the material's brightness varying with the...
grey mid-lateral band is usually present, normally with an accompanying wide dusky band below on the lower sides. The fins are hyaline
Hyaline
The term hyaline denotes a substance with a glass-like appearance.-Histopathology:In histopathological medical usage, a hyaline substance appears glassy and pink after being stained with haematoxylin and eosin — usually it is an acellular, proteinaceous material...
in colour, with only the spinous first dorsal fin having a light dusting of fine black spots at the tip.
Distribution and habitat
S. chondropus ranges from South AfricaSouth Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
, northward along the west Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
n coast to Pakistan
Pakistan
Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...
, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
, Myanmar
Myanmar
Burma , officially the Republic of the Union of Myanmar , is a country in Southeast Asia. Burma is bordered by China on the northeast, Laos on the east, Thailand on the southeast, Bangladesh on the west, India on the northwest, the Bay of Bengal to the southwest, and the Andaman Sea on the south....
, Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
, northern New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
, Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
, Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
and Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
. It has never recorded from southern New Guinea or Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. The species inhabits shallow coastal waters, from depths of 0 to 5 m. In eastern Taiwan, blackish substrates
Substrate (marine biology)
Stream substrate is the material that rests at the bottom of a stream. There are several classification guides. One is:*Mud – silt and clay.*Sand – Particles between 0.06 and 2 mm in diameter.*Granule – Between 2 and 4 mm in diameter....
with a strong current and wave action are inhabited, while in India it has been known to enter estuaries. The reduced swim bladder and modified pelvic fin indicates that this species is demersal and may use the pelvic fin pads somewhat like sled runners on the substrate.
Relationship to humans
The club-foot whiting is commonly taken by seine net throughout its range and is generally sold fresh in local marketMarket
A market is one of many varieties of systems, institutions, procedures, social relations and infrastructures whereby parties engage in exchange. While parties may exchange goods and services by barter, most markets rely on sellers offering their goods or services in exchange for money from buyers...
s alongside other species of sillaginid. Small subsidence fisheries in India are known to take substantial amounts of the species as well.