Loricariidae
Encyclopedia
Loricariidae is the largest family
of catfish
(Order Siluriformes), with almost 700 species and new species being described each year. Loricariids originate from fresh water
habitats of Costa Rica
, Panama
, and tropical and subtropical South America
. These fish are noted for the bony plates covering their bodies and their suckermouth
s. Several genera
are sold as "plecos", notably the suckermouth catfish, Hypostomus plecostomus
, and are popular as aquarium
fish.
Members of the family Loricariidae are commonly referred to as suckermouth armoured catfishes, armoured catfish
, 'plecos' or simply 'plecs'; a shortened form of the species name plecostomus
.
These names are used practically interchangeably when referring to the Loricariidae. The name "Plecostomus" and its shortened forms have become synonymous with the Loricariidae in general, since Plecostomus plecostomus (now called Hypostomus plecostomus) was one of the first species imported into the fishkeeping hobby. This can cause some confusion as some unrelated fish may also be called plecostomus, such as the "Borneo Plecostomus", which are actually balitorid fishes.
In their native range, these fish are known as cascudos or acarís.
'; this has been become common since imports of loricariid catfish from South America often included specimens that had not been taxonomically described. Currently L-numbers are used not only by fishkeeping enthusiasts but by biologists since they represent a useful stopgap until a new species of fish is given a full taxonomic name. It should be noted that in some cases two different L-numbered catfish have turned out to be different populations of the same species, while in other cases multiple (but superficially similar) species have all been traded under a single L-number.
assemblage in even the earliest classifications of the Siluriformes, meaning that it consists of a natural grouping with a common ancestor and all of its descendents. Loricariidae is one of seven families in the superfamily Loricarioidea
, along with Amphiliidae, Trichomycteridae
, Nematogenyidae, Callichthyidae
, Scoloplacidae, and Astroblepidae. Some of these families also exhibit suckermouths or armor, although never together as in Loricariids.
This is the largest catfish
family, including about 684 species in around 92 genera, with new species being described each year. However, this family is in flux and revisions are likely. For example, the subfamily Ancistrinae is accepted in as late as the 2006 edition of Nelson's Fishes of the World
; it later becomes grouped as a tribe because of its recognition as a sister group
to the Pterygoplichthyini. Under Ambruster, six subfamilies are recognized: Delturinae
, Hypoptopomatinae
, Hypostominae
, Lithogeneinae, Loricariinae
, and Neoplecostominae
.
Monophyly for the family is strongly supported, except, possibly, the inclusion of Lithogenes
. Lithogenes is the only genus within the subfamily Lithogeneinae. This genus and subfamily, the most basal
group in Loricariidae, is the sister group
to the rest of the family. Neoplecostominae is the most basal group among the loricariids with the exception of Lithogeneinae. However, the genera of Neoplecostominae do not appear to form a monophyletic
assemblage. The two subfamilies Loricariinae and Hypoptopomatinae appear to be generally regarded as monophyletic. However, the monophyly and composition of the other subfamilies are currently being examined and will likely be altered substantially in the future. Hypostominae is the largest subfamily of Loricariidae. It is made up of five tribe
s. Four of the five tribes, Corymbophanini, Hypostomini, Pterygoplichthyini
, and Rhinelepini
, include about 24 genera. The fifth and largest tribe, Ancistrini
(formerly recognized as its own subfamily), includes 30 genera.
Loricariid fossil
s are extremely rare. The fossil record of Loricariidae extends back to the upper Miocene
. Within the superfamily Loricarioidea
, Loricariidae is the most derived
; in this superfamily, there is a trend toward increasingly complex jaw morphology, which may have allowed for the great diversification of the Loricariidae, which have the most advanced jaws.
; on the other hand, most species are generally restricted to small geographic ranges. Loricariids are found in fresh water
habitats of Costa Rica
, Panama
, and South America
. Species occur in swift-flowing streams from the lowlands up to 3,000 metres in elevation. They can also be found in a variety of other freshwater environments. They can be found in torrential mountain rivers, quiet brackish estuaries, black acidic waters, and even in subterranean habitats.
This family has extremely variable color patterns and body shapes. Loricariids are characterized by bony plates covering their body, similar to the bony plates in callichthyids
(In Latin
, lorica means corselet
). These fish exhibit a ventral
suckermouth with papillae (small projections) on the lips. When present, the adipose fin usually has a spine at the forward edge. These fish have, when they are present, a unique pair of maxillary barbels
. These fish have relatively long intestines due to their usually herbivorous
or detrivorous diets. The body is characteristically depressed in this family. Taste bud
s cover almost the entire surface of the body and fin spines. The length can range from 3 centimetres (1.2 in) in some Otocinclus
to over 100 centimetres (39.4 in) in Panaque
, Acanthicus
, and Pterygoplichthys
.
One of the most obvious characteristics of the loricariids is the suckermouth
. The modified mouth and lips allow the fish to feed, breathe, and attach to the substrate through suction. It was once believed that lips could not function as a sucker while respiration continued as the inflowing water would cause the system to fail; however, it has been demonstrated that respiration and suction can function simultaneously. Inflowing water passing under the sucker is limited to a thin stream immediately behind each maxillary barbel; the maxilla
e in loricariids support only small maxillary barbels and are primarily used to mediate the lateral lip tissue in which they are embedded, preventing failure of suction during inspiration. To achieve suction, the fish pressed its lips against the substrate and inflates its mouth, causing negative pressure.
Also, unlike most other catfish, the premaxilla
e are highly mobile, and the lower jaws have evolved towards a medial position with the teeth pointed rostroventrally; these are important evolutionary innovations. The fish rotates its lower and upper jaws to scrape the substrate. The lower jaws are most mobile.
Loricariid catfishes have evolved several modifications of the digestive tract that function as accessory respiratory organ
s or hydrostatic organs. These complex structures would have been independently evolved a number of times. This includes an enlarged stomach in the Pterygoplichthyini, Hypostomus, and Lithoxus
, a U-shaped diverticulum
in Rhinelepini, and a ring-like diverticulum in Otocinclus
. However, even loricariids with an unmodified stomach have a slight ability to breathe air.
Considerable sexual dimorphism
occurs in this family, most pronounced during the breeding season. For example, in Loricariichthys
, the male has a large expansion of its lower lip, which it uses to hold a clutch of eggs. Ancistrus
males have snouts with fleshy tentacles. In loricariids, odontode
s develop almost anywhere on the external surface of the body and first appear soon after hatching; odontodes appear in a variety of shapes and sizes and are often sexually dimorphic, being larger in breeding males. In most Ancistrini
species, sharp evertible cheek spines (elongated odontodes) are often more developed in males and are used in intraspecific displays and combat.
Unusually for bony fish, many species have a modified iris
called an omega iris. The top part of the iris descends to form a loop which can expand and contract called an iris operculum; when light levels are high, the pupil reduces in diameter and the loop expands to cover the center of the pupil giving rise to a crescent
shaped light transmitting portion. This feature gets its name from its similarity to an upside-down Greek letter omega
(Ω). The origins of this structure are unknown, but it has been suggested that breaking up the outline of the highly visible eye aids camouflage
in what are often highly mottled animals. Species in the tribe Rhinelepini
are an exception among loricariids, having a normal, circular iris. The presence or absence of the iris operculum can also be used for identification of species in the subfamily Loricariinae
.
s this family. There is a wide variation in the chromosome number in this fish group, ranging from 2n = 36 in the Loricariinae
, Rineloricaria latirostris, to 2n = 96 in a species of Upsilodus (Hemipsilichthys
). Most members of the Ancistrini and Pterygoplichthyini have 52 chromosomes. Karyotypic evolution by means of centric fusion
s and centric fissions seems to be a common feature among loricariids; this is demonstrated by a higher number of biarmed chromosomes in species with lower diploid number and many uniarmed chromosomes in species with higher diploid numbers. Studies conducted with representatives of some genera of Hypostominae showed that within this
group, the diploid number ranges from 2n = 52 to 2n = 80. However, the supposed wide karyotypic diversity that the family Loricariidae or the subfamily Hypostominae
would present is almost exclusively restricted to the genus Hypostomus
, and the species from the other genera had a conserved diploid number. It has been found in some species that there is a ZZ/ZW sex-determination system
.
The suckermouth exhibited by these catfish allow them to adhere to objects in their habitats, even in fast-flowing waters. The mouth and teeth also are adapted to feed on a variety of foods such as algae
, invertebrate
s, and detritus
. Some species, notably the Panaque
, are known for xylophagy
, or the ability to digest wood
.
Most species of Loricariids are nocturnal animal
s. Some species are territorial
, while others, such as Otocinclus
, prefer to live in groups.
Air-breathing is well known among many loricariids. The ability to breathe air is dependent on the risk of hypoxia
faced by a species; torrent-dwelling species tend to have no ability to breathe air, while low-land, pool-dwelling species such as those of Hypostomus have a great ability to breathe air. Pterygoplichthys are known for being kept out of water and sold alive in fish markets, surviving up to 30 hours out of water. Loricariids are facultative air breathers; they will only breathe air if under stress and will only use their gills in situations when oxygen levels are high. The dry season is a likely time for this; there would be little food in the stomach, which would allow its use for air breathing.
Loricariids exhibit a wide range of reproductive strategies, including cavity spawning, attachment of eggs on the underside of rocks, and egg-carrying. Parental care is usually well-developed and the male guards the eggs and sometimes the larvae. The eggs hatch after between 4 and 20 days, depending on the species.
Loricariids are popular aquarium
fish, where they are often sold as "plecs", "plecos" or "plecostomus". These fish are often purchased because of their algae-eating
habits, though this role may not be carried out. Most species are in fact detritivore
s. A great many species of Loricariids are also sold for their ornamental qualities, representing many body shapes and colors.
Most species of Loricariids are nocturnal and will shy away from bright light, appreciating some sort of cover to hide under throughout the day. As they often originate from habitats with fast-moving water, filtration
should be vigorous.
A number of species of Loricariids have been bred in captivity.
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...
(Order Siluriformes), with almost 700 species and new species being described each year. Loricariids originate from fresh water
Fresh Water
Fresh Water is the debut album by Australian rock and blues singer Alison McCallum, released in 1972. Rare for an Australian artist at the time, it came in a gatefold sleeve...
habitats of Costa Rica
Costa Rica
Costa Rica , officially the Republic of Costa Rica is a multilingual, multiethnic and multicultural country in Central America, bordered by Nicaragua to the north, Panama to the southeast, the Pacific Ocean to the west and the Caribbean Sea to the east....
, Panama
Panama
Panama , officially the Republic of Panama , is the southernmost country of Central America. Situated on the isthmus connecting North and South America, it is bordered by Costa Rica to the northwest, Colombia to the southeast, the Caribbean Sea to the north and the Pacific Ocean to the south. The...
, and tropical and subtropical South America
South 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...
. These fish are noted for the bony plates covering their bodies and their suckermouth
Suckermouth
In fishes, a suckermouth is a ventrally-oriented mouth adapted for grazing on algae and small organisms that grow on submerged objects....
s. Several genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
are sold as "plecos", notably the suckermouth catfish, Hypostomus plecostomus
Hypostomus plecostomus
Hypostomus plecostomus, the suckermouth catfish or common pleco, is a tropical fish belonging to the armored catfish family , named for the armor-like longitudinal rows of scutes that cover the upper parts of the head and body...
, and are popular as aquarium
Aquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
fish.
Common names
Armoured catfish (disambiguation)
Armoured catfish may refer to any of the following:*Loricariidae family: The armoured suckermouth catfish, also known as suckermouth catfish, armoured catfish or simply 'plecs' or 'plecos'*Callichthyidae family: Armoured catfish, includes the genera:...
, 'plecos' or simply 'plecs'; a shortened form of the species name plecostomus
Plecostomus
Hypostomus plecostomus is the scientific name for a type of freshwater tropical Central and South American fish belonging to the family Loricariidae. They are large algae eaters, and to differentiate them from small algae eaters, they are often referred to as plecostomus, often abbreviated as...
.
These names are used practically interchangeably when referring to the Loricariidae. The name "Plecostomus" and its shortened forms have become synonymous with the Loricariidae in general, since Plecostomus plecostomus (now called Hypostomus plecostomus) was one of the first species imported into the fishkeeping hobby. This can cause some confusion as some unrelated fish may also be called plecostomus, such as the "Borneo Plecostomus", which are actually balitorid fishes.
In their native range, these fish are known as cascudos or acarís.
L-numbers
Some types of loricariids are often referred to by their 'L-numberL-number
The L-number system is a semi-scientific classification system of catfish based on photographs of shipments of tropical catfish of the family Loricariidae published by the aquarium magazine DATZ ....
'; this has been become common since imports of loricariid catfish from South America often included specimens that had not been taxonomically described. Currently L-numbers are used not only by fishkeeping enthusiasts but by biologists since they represent a useful stopgap until a new species of fish is given a full taxonomic name. It should be noted that in some cases two different L-numbered catfish have turned out to be different populations of the same species, while in other cases multiple (but superficially similar) species have all been traded under a single L-number.
Taxonomy and evolution
Because of their highly specialized morphology, loricariids have been recognized as a monophyleticMonophyly
In common cladistic usage, a monophyletic group is a taxon which forms a clade, meaning that it contains all the descendants of the possibly hypothetical closest common ancestor of the members of the group. The term is synonymous with the uncommon term holophyly...
assemblage in even the earliest classifications of the Siluriformes, meaning that it consists of a natural grouping with a common ancestor and all of its descendents. Loricariidae is one of seven families in the superfamily Loricarioidea
Loricarioidea
Loricarioidea is a superfamily of catfishes . It contains the six families Trichomycteridae, Nematogenyiidae, Callichthyidae, Scoloplacidae, Astroblepidae, and Loricariidae. Some schemes also include Amphiliidae...
, along with Amphiliidae, Trichomycteridae
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....
, Nematogenyidae, Callichthyidae
Callichthyidae
Callichthyidae is a family of catfishes , called armored catfishes due to the two rows of bony plates running down the length of the body. This family contains some of the most popular freshwater aquarium fish, such as the Corydoras.-Taxonomy:The family derives its name from the Greek words kallis...
, Scoloplacidae, and Astroblepidae. Some of these families also exhibit suckermouths or armor, although never together as in Loricariids.
This is the largest 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...
family, including about 684 species in around 92 genera, with new species being described each year. However, this family is in flux and revisions are likely. For example, the subfamily Ancistrinae is accepted in as late as the 2006 edition of Nelson's Fishes of the World
Fishes of the World
Fishes of the World by Joseph S. Nelson is a standard reference for fish systematics. Now in its fourth edition, the work is a comprehensive overview of the 25,000-plus species known to science....
; it later becomes grouped as a tribe because of its recognition as a sister group
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
to the Pterygoplichthyini. Under Ambruster, six subfamilies are recognized: Delturinae
Delturinae
Delturinae is a subfamily of catfishes of the family Loricariidae. It includes two genera, Delturus and Hemipsilichthys. This group is sister to all other loricariids except Lithogenes...
, Hypoptopomatinae
Hypoptopomatinae
Hypoptopomatinae is a subfamily of catfishes of the family Loricariidae.Hypoptopomatinae is a monophyletic assemblage within the family Loricariidae. It is composed by 17 genera and approximately 80 species. This subfamily represents about one-tenth of all loricariid species.It is divided into two...
, Hypostominae
Hypostominae
Hypostominae is a subfamily of catfishes of the family Loricariidae.Studies conducted with representatives of some genera of Hypostominae showed that within thisgroup, the diploid number ranges from 2n = 52 to 2n = 80...
, Lithogeneinae, Loricariinae
Loricariinae
Loricariinae is a subfamily of the family Loricariidae of catfish . This subfamily is divided into two tribes and about 30 genera.-Taxonomy:...
, and Neoplecostominae
Neoplecostominae
Neoplecostominae is a subfamily of catfishes of the family Loricariidae. Species of Neoplecostominae live in high-montane, swift-flowing river habitats.-Taxonomy:...
.
Monophyly for the family is strongly supported, except, possibly, the inclusion of Lithogenes
Lithogenes
Lithogenes is a genus of catfish of the family Loricariidae. It is the only genus within the subfamily Lithogeneinae. This genus contains two species: L. villosus, the type species, and L. valencia, a possibly extinct species.-Taxonomy:L. villosus was described in 1909 by Carl H. Eigenmann. L...
. Lithogenes is the only genus within the subfamily Lithogeneinae. This genus and subfamily, the most basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
group in Loricariidae, is the sister group
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
to the rest of the family. Neoplecostominae is the most basal group among the loricariids with the exception of Lithogeneinae. However, the genera of Neoplecostominae do not appear to form a monophyletic
Monophyly
In common cladistic usage, a monophyletic group is a taxon which forms a clade, meaning that it contains all the descendants of the possibly hypothetical closest common ancestor of the members of the group. The term is synonymous with the uncommon term holophyly...
assemblage. The two subfamilies Loricariinae and Hypoptopomatinae appear to be generally regarded as monophyletic. However, the monophyly and composition of the other subfamilies are currently being examined and will likely be altered substantially in the future. Hypostominae is the largest subfamily of Loricariidae. It is made up of five tribe
Tribe (biology)
In biology, a tribe is a taxonomic rank between family and genus. It is sometimes subdivided into subtribes.Some examples include the tribes: Canini, Acalypheae, Hominini, Bombini, and Antidesmeae.-See also:* Biological classification* Rank...
s. Four of the five tribes, Corymbophanini, Hypostomini, Pterygoplichthyini
Pterygoplichthyini
Pterygoplichthyini is a tribe of catfishes of the family Loricariidae. It includes two genera, Pterygoplichthys and the currently undescribed genus referred to as the Hemiancistrus annectens group. This group was earlier misspelled as Pterygoplichthini...
, and Rhinelepini
Rhinelepini
Rhinelepini is a tribe of armored suckermouth catfish family within the Hypostominae subfamily.-Taxonomy:This tribe is a well diagnosed monophyletic group currently containing three genera: Pogonopoma, Pseudorinelepis, and Rhinelepis. When the tribe was first described, Pogonopomoides was a valid...
, include about 24 genera. The fifth and largest tribe, Ancistrini
Ancistrini
Ancistrini is a tribe of catfishes of the family Loricariidae.-Taxonomy:Ancistrini has previously been considered a loricariid subfamily. However, it was realized that the subfamily Hypostominae would be paraphyletic if Ancistrinae continued to be recognized...
(formerly recognized as its own subfamily), includes 30 genera.
Loricariid fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s are extremely rare. The fossil record of Loricariidae extends back to the upper Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
. Within the superfamily Loricarioidea
Loricarioidea
Loricarioidea is a superfamily of catfishes . It contains the six families Trichomycteridae, Nematogenyiidae, Callichthyidae, Scoloplacidae, Astroblepidae, and Loricariidae. Some schemes also include Amphiliidae...
, Loricariidae is the most derived
Derived
In phylogenetics, a derived trait is a trait that is present in an organism, but was absent in the last common ancestor of the group being considered. This may also refer to structures that are not present in an organism, but were present in its ancestors, i.e. traits that have undergone secondary...
; in this superfamily, there is a trend toward increasingly complex jaw morphology, which may have allowed for the great diversification of the Loricariidae, which have the most advanced jaws.
Distribution and habitat
The family Loricariidae is vastly distributed over both sides of the AndesAndes
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...
; on the other hand, most species are generally restricted to small geographic ranges. Loricariids are found in fresh water
Fresh Water
Fresh Water is the debut album by Australian rock and blues singer Alison McCallum, released in 1972. Rare for an Australian artist at the time, it came in a gatefold sleeve...
habitats of Costa Rica
Costa Rica
Costa Rica , officially the Republic of Costa Rica is a multilingual, multiethnic and multicultural country in Central America, bordered by Nicaragua to the north, Panama to the southeast, the Pacific Ocean to the west and the Caribbean Sea to the east....
, Panama
Panama
Panama , officially the Republic of Panama , is the southernmost country of Central America. Situated on the isthmus connecting North and South America, it is bordered by Costa Rica to the northwest, Colombia to the southeast, the Caribbean Sea to the north and the Pacific Ocean to the south. The...
, and South America
South 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...
. Species occur in swift-flowing streams from the lowlands up to 3,000 metres in elevation. They can also be found in a variety of other freshwater environments. They can be found in torrential mountain rivers, quiet brackish estuaries, black acidic waters, and even in subterranean habitats.
Description and biology
Callichthyidae
Callichthyidae is a family of catfishes , called armored catfishes due to the two rows of bony plates running down the length of the body. This family contains some of the most popular freshwater aquarium fish, such as the Corydoras.-Taxonomy:The family derives its name from the Greek words kallis...
(In Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
, lorica means corselet
Corselet
A corselet or corselette is a type of foundation garment, sharing elements of both brassieres and girdles. It may incorporate lace in front or in back...
). These fish exhibit a ventral
Anatomical terms of location
Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...
suckermouth with papillae (small projections) on the lips. When present, the adipose fin usually has a spine at the forward edge. These fish have, when they are present, a unique pair of maxillary barbels
Barbel (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...
. These fish have relatively long intestines due to their usually herbivorous
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
or detrivorous diets. The body is characteristically depressed in this family. Taste bud
Taste bud
Taste buds contain the receptors for taste. They are located around the small structures on the upper surface of the tongue, soft palate, upper esophagus and epiglottis, which are called papillae. These structures are involved in detecting the five elements of taste perception: salty, sour,...
s cover almost the entire surface of the body and fin spines. The length can range from 3 centimetres (1.2 in) in some Otocinclus
Otocinclus
Otocinclus is a genus of catfish of the family Loricariidae commonly called "dwarf suckers" or "otos". Otocinclus originate from tropical, freshwater rivers in South America.-Taxonomy:...
to over 100 centimetres (39.4 in) in Panaque
Panaque
The genus Panaque contains a small number of small to medium sized South American armoured catfishes that are notable for being among the very few vertebrates that feed extensively on wood. In addition, algae and aufwuchs are an important part of the diet, and they use their rasping teeth to...
, Acanthicus
Acanthicus
Acanthicus is a genus of catfishes of the family Loricariidae. It includes two species, A. adonis and A. hystrix....
, and Pterygoplichthys
Pterygoplichthys
Pterygoplichthys is a genus of the armored catfish family Loricariidae. These fish are commonly known as sailfin armoured catfish or sailfin plecs.-Taxonomy:This genus was described in 1858 by Theodore Nicholas Gill...
.
One of the most obvious characteristics of the loricariids is the suckermouth
Suckermouth
In fishes, a suckermouth is a ventrally-oriented mouth adapted for grazing on algae and small organisms that grow on submerged objects....
. The modified mouth and lips allow the fish to feed, breathe, and attach to the substrate through suction. It was once believed that lips could not function as a sucker while respiration continued as the inflowing water would cause the system to fail; however, it has been demonstrated that respiration and suction can function simultaneously. Inflowing water passing under the sucker is limited to a thin stream immediately behind each maxillary barbel; the maxilla
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
e in loricariids support only small maxillary barbels and are primarily used to mediate the lateral lip tissue in which they are embedded, preventing failure of suction during inspiration. To achieve suction, the fish pressed its lips against the substrate and inflates its mouth, causing negative pressure.
Also, unlike most other catfish, the premaxilla
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
e are highly mobile, and the lower jaws have evolved towards a medial position with the teeth pointed rostroventrally; these are important evolutionary innovations. The fish rotates its lower and upper jaws to scrape the substrate. The lower jaws are most mobile.
Loricariid catfishes have evolved several modifications of the digestive tract that function as accessory respiratory organ
Respiration organ
Respiratory organs are used by most, or all, animals to exchange the gases necessary for their life function known as respiration...
s or hydrostatic organs. These complex structures would have been independently evolved a number of times. This includes an enlarged stomach in the Pterygoplichthyini, Hypostomus, and Lithoxus
Lithoxus
Lithoxus is a genus of catfishes of the family Loricariidae. It includes eight species, L. boujardi, L. bovallii, L. jantjae, L. lithoides, L. pallidimaculatus, L. planquettei, L. stocki, and L. surinamensis.-Taxonomy:Lithoxus is supported as a monophyletic sister to Exastilithoxus...
, a U-shaped diverticulum
Diverticulum
A diverticulum is medical or biological term for an outpouching of a hollow structure in the body. Depending upon which layers of the structure are involved, they are described as being either true or false....
in Rhinelepini, and a ring-like diverticulum in Otocinclus
Otocinclus
Otocinclus is a genus of catfish of the family Loricariidae commonly called "dwarf suckers" or "otos". Otocinclus originate from tropical, freshwater rivers in South America.-Taxonomy:...
. However, even loricariids with an unmodified stomach have a slight ability to breathe air.
Considerable sexual dimorphism
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
occurs in this family, most pronounced during the breeding season. For example, in Loricariichthys
Loricariichthys
Loricariichthys is a genus of catfishes of the family Loricariidae.-Taxonomy:This genus is part of the Loricariichthys group within the subfamily Loricariinae; this group also includes the genera Furcodontichthys, Hemiodontichthys, Limatulichthys, and Pseudoloricaria...
, the male has a large expansion of its lower lip, which it uses to hold a clutch of eggs. Ancistrus
Ancistrus
Ancistrus is a genus of freshwater fish in the family Loricariidae of order Siluriformes. Fish of this genus are commonly known as the bushynose or bristlenose plecos.-Taxonomy:The type species is Ancistrus cirrhosus...
males have snouts with fleshy tentacles. In loricariids, odontode
Odontode
Odontodes, or dermal teeth, are hard structures found on the external surfaces of animals or near internal openings. They comprise a soft pulp surrounded by dentine and covered by a mineralized substance such as enamel, a structure similar to that of teeth. They generally do not have the same...
s develop almost anywhere on the external surface of the body and first appear soon after hatching; odontodes appear in a variety of shapes and sizes and are often sexually dimorphic, being larger in breeding males. In most Ancistrini
Ancistrini
Ancistrini is a tribe of catfishes of the family Loricariidae.-Taxonomy:Ancistrini has previously been considered a loricariid subfamily. However, it was realized that the subfamily Hypostominae would be paraphyletic if Ancistrinae continued to be recognized...
species, sharp evertible cheek spines (elongated odontodes) are often more developed in males and are used in intraspecific displays and combat.
Iris (anatomy)
The iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupils and thus the amount of light reaching the retina. "Eye color" is the color of the iris, which can be green, blue, or brown. In some cases it can be hazel , grey, violet, or even pink...
called an omega iris. The top part of the iris descends to form a loop which can expand and contract called an iris operculum; when light levels are high, the pupil reduces in diameter and the loop expands to cover the center of the pupil giving rise to a crescent
Crescent
In art and symbolism, a crescent is generally the shape produced when a circular disk has a segment of another circle removed from its edge, so that what remains is a shape enclosed by two circular arcs of different diameters which intersect at two points .In astronomy, a crescent...
shaped light transmitting portion. This feature gets its name from its similarity to an upside-down Greek letter omega
Omega
Omega is the 24th and last letter of the Greek alphabet. In the Greek numeric system, it has a value of 800. The word literally means "great O" , as opposed to omicron, which means "little O"...
(Ω). The origins of this structure are unknown, but it has been suggested that breaking up the outline of the highly visible eye aids camouflage
Camouflage
Camouflage is a method of concealment that allows an otherwise visible animal, military vehicle, or other object to remain unnoticed, by blending with its environment. Examples include a leopard's spotted coat, the battledress of a modern soldier and a leaf-mimic butterfly...
in what are often highly mottled animals. Species in the tribe Rhinelepini
Rhinelepini
Rhinelepini is a tribe of armored suckermouth catfish family within the Hypostominae subfamily.-Taxonomy:This tribe is a well diagnosed monophyletic group currently containing three genera: Pogonopoma, Pseudorinelepis, and Rhinelepis. When the tribe was first described, Pogonopomoides was a valid...
are an exception among loricariids, having a normal, circular iris. The presence or absence of the iris operculum can also be used for identification of species in the subfamily Loricariinae
Loricariinae
Loricariinae is a subfamily of the family Loricariidae of catfish . This subfamily is divided into two tribes and about 30 genera.-Taxonomy:...
.
Genetics
As of 2000, only 56 loricariid species have been cytogenically investigated. It has been shown that 2n = 54 is the basal diploid number of chromosomeChromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
s this family. There is a wide variation in the chromosome number in this fish group, ranging from 2n = 36 in the Loricariinae
Loricariinae
Loricariinae is a subfamily of the family Loricariidae of catfish . This subfamily is divided into two tribes and about 30 genera.-Taxonomy:...
, Rineloricaria latirostris, to 2n = 96 in a species of Upsilodus (Hemipsilichthys
Hemipsilichthys
Hemipsilichthys is a genus of catfishes belonging to the family Loricariidae. These wide-mouthed freshwater catfishes are all restricted to Brazil, mostly in the coastal basins of the south and southeast with one species, Hemipsilichthys regani, further north in the Amazon basin...
). Most members of the Ancistrini and Pterygoplichthyini have 52 chromosomes. Karyotypic evolution by means of centric fusion
Robertsonian translocation
Robertsonian translocation is a common form of chromosomal rearrangement that in humans occurs in the five acrocentric chromosome pairs, namely 13, 14, 15, 21, and 22. Other translocations occur but do not lead to a viable fetus. They are named after the American biologist William Rees Brebner...
s and centric fissions seems to be a common feature among loricariids; this is demonstrated by a higher number of biarmed chromosomes in species with lower diploid number and many uniarmed chromosomes in species with higher diploid numbers. Studies conducted with representatives of some genera of Hypostominae showed that within this
group, the diploid number ranges from 2n = 52 to 2n = 80. However, the supposed wide karyotypic diversity that the family Loricariidae or the subfamily Hypostominae
would present is almost exclusively restricted to the genus Hypostomus
Hypostomus
Hypostomus is the largest genus of the armored catfish family Loricariidae. It includes the popular freshwater aquarium fish Plecostomus...
, and the species from the other genera had a conserved diploid number. It has been found in some species that there is a ZZ/ZW sex-determination system
Sex-determination system
A sex-determination system is a biological system that determines the development of sexual characteristics in an organism. Most sexual organisms have two sexes. In many cases, sex determination is genetic: males and females have different alleles or even different genes that specify their sexual...
.
Ecology
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
, invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s, and detritus
Detritus
Detritus is a biological term used to describe dead or waste organic material.Detritus may also refer to:* Detritus , a geological term used to describe the particles of rock produced by weathering...
. Some species, notably the Panaque
Panaque
The genus Panaque contains a small number of small to medium sized South American armoured catfishes that are notable for being among the very few vertebrates that feed extensively on wood. In addition, algae and aufwuchs are an important part of the diet, and they use their rasping teeth to...
, are known for xylophagy
Xylophagy
Xylophagy is a term used in ecology to describe the habits of an herbivorous animal whose diet consists primarily of wood. The word derives from Greek ξυλοφάγος "eating wood", from ξύλον "wood" and φαγεῖν "to eat", an ancient Greek name for a kind of a worm-eating bird...
, or the ability to digest wood
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...
.
Most species of Loricariids are nocturnal animal
Nocturnal animal
Nocturnality is an animal behavior characterized by activity during the night and sleeping during the day. The common adjective is "nocturnal"....
s. Some species are territorial
Territory (animal)
In ethology the term territory refers to any sociographical area that an animal of a particular species consistently defends against conspecifics...
, while others, such as Otocinclus
Otocinclus
Otocinclus is a genus of catfish of the family Loricariidae commonly called "dwarf suckers" or "otos". Otocinclus originate from tropical, freshwater rivers in South America.-Taxonomy:...
, prefer to live in groups.
Air-breathing is well known among many loricariids. The ability to breathe air is dependent on the risk of hypoxia
Hypoxia (medical)
Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...
faced by a species; torrent-dwelling species tend to have no ability to breathe air, while low-land, pool-dwelling species such as those of Hypostomus have a great ability to breathe air. Pterygoplichthys are known for being kept out of water and sold alive in fish markets, surviving up to 30 hours out of water. Loricariids are facultative air breathers; they will only breathe air if under stress and will only use their gills in situations when oxygen levels are high. The dry season is a likely time for this; there would be little food in the stomach, which would allow its use for air breathing.
Loricariids exhibit a wide range of reproductive strategies, including cavity spawning, attachment of eggs on the underside of rocks, and egg-carrying. Parental care is usually well-developed and the male guards the eggs and sometimes the larvae. The eggs hatch after between 4 and 20 days, depending on the species.
In the aquarium
Aquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
fish, where they are often sold as "plecs", "plecos" or "plecostomus". These fish are often purchased because of their algae-eating
Algae eater
Algae eater is a common name for many bottom-dwelling fish that feed on algae. Algae eaters are important for the fishkeeping hobby and many are commonly kept by hobbyists.Some of the common and most popular freshwater algae eaters include:...
habits, though this role may not be carried out. Most species are in fact detritivore
Detritivore
Detritivores, also known as detritophages or detritus feeders or detritus eaters or saprophages, are heterotrophs that obtain nutrients by consuming detritus . By doing so, they contribute to decomposition and the nutrient cycles...
s. A great many species of Loricariids are also sold for their ornamental qualities, representing many body shapes and colors.
Most species of Loricariids are nocturnal and will shy away from bright light, appreciating some sort of cover to hide under throughout the day. As they often originate from habitats with fast-moving water, filtration
Filter (aquarium)
Aquarium filters are critical components of both freshwater and marine aquaria. Aquarium filters remove physical and soluble chemical waste products from aquaria, simplifying maintenance...
should be vigorous.
A number of species of Loricariids have been bred in captivity.
External links
- THE LORICARIIDAE by Dr. Jonathan Armbruster - useful website including a taxonomic key.
- Planet Catfish Catalogue of loricariid catfishes
- All Catfish Species Inventory page for Loricariidae