Cetopsidae
Encyclopedia
Cetopsidae is a small family
of catfish
es (order
Siluriformes), commonly called the whale catfishes.
. It is divided into two subfamilies, Cetopsinae and Helogeneinae. Helogeneinae was previously a family-level group, but now it has been reclassified as a subfamily of Cetopsidae. This subfamily contains four species in the genus Helogenes
. The subfamily Cetopsinae contains four genera. Cetopsidium
contains six species, Cetopsis
contains 21 species, Denticetopsis
contains seven species, and Paracetopsis
contains three species; this makes a total of 37 cetopsines. The genera have been changed as recenetly as 2005 with the genera Bathycetopsis, Hemicetopsis, and Pseudocetopsis set in synonymy
with Cetopsis and the description of the new genus Cetopsidium.
Cetopsidium is the sister group to the rest of Cetopsinae. Denticetopsis forms the next sister group to the remaining cetopsine genera. The tribes Cetopsidiini, Denticetopsini, and Cetopsini are erected for the cetopsine genera.
. Latitudinally
, cetopsines extend from northern Colombia
to central Argentina
. They inhabit major habitats such as the Orinoco River, Amazon River
, and the Guyanas
. In trans
-Andean
South America, cetopsines are found along the Pacific slope from the Jurubidá River of Colombia south to the Tumbes River
of northern Peru
. Along the Caribbean
trans-Andean versant, species of cetopsines occur from the Sinú River
of northwestern Colombia east to the Lake Maracaibo
basin of northwestern Venezuela
. East of the Andean Cordillera
s, the Cetopsinae occurs in the Aroa
and Yaracuy River basins along the Caribbean versant of northern Venezuela, through the Orinoco River system and the coastal rivers of the Guianas, south through the Amazon basin to the southern portions of the Río de la Plata
basin. Cetopsines also occur in the Juquiá River
basin of the state of São Paulo
and the São Francisco River
basin of eastern Brazil
. Helogenes, the single genus of Helogeneinae, occurs through much of the Amazon basin, the southern portions of the Orinoco River basin, the coastal rivers of the Guianas, and at least the lower portions of the Tocantins River
.
, and, usually, a lack of dorsal
and pectoral fin spines. In Cetopsinae, the swim bladder
is highly reduced and is enclosed in a bony capsule. Cetopsines lack an adipose fin, while it may be present (though small) in Helogeneinae. Many species are characterized by small eyes that are obscured by a thick, overlying integument
that make them appear blind. The dorsal and pectoral fins usually lack spines, except in Cetopsidium (both present) and Denticetopsis (only pectoral spines present). In most species of Cetopsis and Cetopsidium, mature males have a convex margin to their anal fin and elongated distal filaments of the dorsal and pectoral fin spines.
The maximum length of this family is about 26 centimetres (10.2 in) SL
in Cetopsinae. Cetopsidium are generally smaller in body size than Cetopsis. The maximum length in Helogenes species is 7 centimetres (2.8 in).
s. C. candiru and C. coecutiens are well known to have extremely voracious appetites. These fish will attack carrion
, other living fish while in gillnet
s, and even people. It is erroneously believed by some people that these fish are parasitic like parasitic catfishes
.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of catfish
Catfish
Catfishes are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...
es (order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Siluriformes), commonly called the whale catfishes.
Taxonomy
This family contains five generaGenus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
. It is divided into two subfamilies, Cetopsinae and Helogeneinae. Helogeneinae was previously a family-level group, but now it has been reclassified as a subfamily of Cetopsidae. This subfamily contains four species in the genus Helogenes
Helogenes
Helogenes is a genus of catfish of the family Cetopsidae. It includes four species, H. castaneus, H. gouldingi, H. marmoratus, and H...
. The subfamily Cetopsinae contains four genera. Cetopsidium
Cetopsidium
Cetopsidium is a genus of catfishes of the family Cetopsidae. It includes seven species, C. ferreirai, C. minutum, C. morenoi, C. orientale, C. pemon, C. roae, and C...
contains six species, Cetopsis
Cetopsis
Cetopsis is a genus of catfishes of the family Cetopsidae.-Taxonomy:Cetopsis is one of four genera in the subfamily Cetopsinae within the family Cetopsidae. Cetopsis is greatly expanded from when it only included C. coecutiens...
contains 21 species, Denticetopsis
Denticetopsis
Denticetopsis is a genus of catfishes of the family Cetopsidae. It includes seven species, D. epa, D. iwokrama, D. macilenta, D. praecox, D. royeroi, D. sauli, and D. seducta.-Taxonomy:...
contains seven species, and Paracetopsis
Paracetopsis
Paracetopsis is a genus of catfishes of the family Cetopsidae. It includes three species, P. atahualpa, P. bleekeri, and P. esmeraldas.-Distribution:...
contains three species; this makes a total of 37 cetopsines. The genera have been changed as recenetly as 2005 with the genera Bathycetopsis, Hemicetopsis, and Pseudocetopsis set in synonymy
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
with Cetopsis and the description of the new genus Cetopsidium.
Cetopsidium is the sister group to the rest of Cetopsinae. Denticetopsis forms the next sister group to the remaining cetopsine genera. The tribes Cetopsidiini, Denticetopsini, and Cetopsini are erected for the cetopsine genera.
Distribution
Cetopsids have a wide distribution in South AmericaSouth America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. Latitudinally
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
, cetopsines extend from northern Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
to central Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
. They inhabit major habitats such as the Orinoco River, Amazon River
Amazon River
The Amazon of South America is the second longest river in the world and by far the largest by waterflow with an average discharge greater than the next seven largest rivers combined...
, and the Guyanas
Guyanas
Guyana is a country in South America.Guyana, Guayana, or Guiana may also refer to:*Guayana Esequiba, the territory of Guyana claimed by Venezuela*Guayana Region, an administrative region of Venezuela...
. In trans
Trans
Trans is a Latin noun or prefix, meaning "across", "beyond" or "on the opposite side".Trans may refer to:- Science and technology :* Cis-trans isomerism, in chemistry, a form of stereoisomerism...
-Andean
Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...
South America, cetopsines are found along the Pacific slope from the Jurubidá River of Colombia south to the Tumbes River
Tumbes River
The Tumbes River , is a river in South America.The river's sources are located between Ecuadorian El Oro and Loja provinces. It is the border between El Oro and Loja, and afterwards the border between Loja and the Tumbes Region in Peru...
of northern Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
. Along the Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
trans-Andean versant, species of cetopsines occur from the Sinú River
Sinú River
Sinú River , is a river in northwestern Colombia that flows mostly through the Córdoba Department and into the Caribbean. The river is the third most important river after the Magdalena River and the Cauca River in the Caribbean Region. It is born in the Antioquia Department, flowing south to north...
of northwestern Colombia east to the Lake Maracaibo
Lake Maracaibo
Lake Maracaibo is a large brackish bay in Venezuela at . It is connected to the Gulf of Venezuela by Tablazo Strait at the northern end, and fed by numerous rivers, the largest being the Catatumbo. It is commonly considered a lake rather than a bay or lagoon, and at 13,210 km² it would be the...
basin of northwestern Venezuela
Venezuela
Venezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...
. East of the Andean Cordillera
Cordillera
A cordillera is an extensive chain of mountains or mountain ranges, that runs along a coastline . It comes from the Spanish word cordilla, which is a diminutive of cuerda, or "cord"...
s, the Cetopsinae occurs in the Aroa
Aroa River
The Aroa River is a river in northwestern Venezuela. It runs parallel and west of the Yaracuy River. The Aroa River empties into the Caribbean Sea....
and Yaracuy River basins along the Caribbean versant of northern Venezuela, through the Orinoco River system and the coastal rivers of the Guianas, south through the Amazon basin to the southern portions of the Río de la Plata
Río de la Plata
The Río de la Plata —sometimes rendered River Plate in British English and the Commonwealth, and occasionally rendered [La] Plata River in other English-speaking countries—is the river and estuary formed by the confluence of the Uruguay River and the Paraná River on the border between Argentina and...
basin. Cetopsines also occur in the Juquiá River
Juquiá River
The Juquiá River is a river of São Paulo state in southeastern Brazil.-References:*...
basin of the state of São Paulo
São Paulo (state)
São Paulo is a state in Brazil. It is the major industrial and economic powerhouse of the Brazilian economy. Named after Saint Paul, São Paulo has the largest population, industrial complex, and economic production in the country. It is the richest state in Brazil...
and the São Francisco River
São Francisco River
The São Francisco is a river in Brazil. With a length of , it is the longest river that runs entirely in Brazilian territory, and the fourth longest in South America and overall in Brazil...
basin of eastern Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
. Helogenes, the single genus of Helogeneinae, occurs through much of the Amazon basin, the southern portions of the Orinoco River basin, the coastal rivers of the Guianas, and at least the lower portions of the Tocantins River
Tocantins River
The Tocantins is a river in Brazil, the central fluvial artery of the country. In the Tupi language, its name means "toucan's beak" . It runs from south to north for about 2,640 km. It is not really a branch of the Amazon River, although usually so considered, since its waters flow into the...
.
Description
The family Cetopsidae includes species of small- to medium-sized catfishes which share an anal fin with a long base, the lack of nasal barbelsBarbel (anatomy)
A barbel on a fish is a slender, whiskerlike tactile organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, sturgeon, the zebrafish and some species of shark...
, and, usually, a lack of dorsal
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...
and pectoral fin spines. In Cetopsinae, the swim bladder
Gas bladder
The swim bladder, gas bladder, fish maw or air bladder is an internal gas-filled organ that contributes to the ability of a fish to control its buoyancy, and thus to stay at the current water depth without having to waste energy in swimming...
is highly reduced and is enclosed in a bony capsule. Cetopsines lack an adipose fin, while it may be present (though small) in Helogeneinae. Many species are characterized by small eyes that are obscured by a thick, overlying integument
Integumentary system
The integumentary system is the organ system that protects the body from damage, comprising the skin and its appendages...
that make them appear blind. The dorsal and pectoral fins usually lack spines, except in Cetopsidium (both present) and Denticetopsis (only pectoral spines present). In most species of Cetopsis and Cetopsidium, mature males have a convex margin to their anal fin and elongated distal filaments of the dorsal and pectoral fin spines.
The maximum length of this family is about 26 centimetres (10.2 in) SL
Fish measurement
Fish measurement refers to the measuring of the length of individual fish and of various parts of their anatomy. These data are used in many areas of ichthyology, including taxonomy and fisheries biology.-Overall length:...
in Cetopsinae. Cetopsidium are generally smaller in body size than Cetopsis. The maximum length in Helogenes species is 7 centimetres (2.8 in).
Ecology
Most cetopsids feed on insectInsect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s. C. candiru and C. coecutiens are well known to have extremely voracious appetites. These fish will attack carrion
Carrion
Carrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters include vultures, hawks, eagles, hyenas, Virginia Opossum, Tasmanian Devils, coyotes, Komodo dragons, and burying beetles...
, other living fish while in gillnet
Gillnet
Gillnetting is a common fishing method used by commercial and artisanal fishermen of all the oceans and in some freshwater and estuary areas. The gillnet also is used by fisheries scientists to monitor fish populations. Because gillnets can be so effective their use is closely monitored and...
s, and even people. It is erroneously believed by some people that these fish are parasitic like parasitic catfishes
Trichomycteridae
Trichomycteridae is a family of catfishes commonly known as the pencil or parasitic catfishes. This family includes the infamous candiru fish, feared by some people for its alleged habit of entering into the urethra of humans....
.