Cavefish
Encyclopedia
The Amblyopsidae, are commonly named: cavefish, blindfish, swampfish, etc. They are small cyprinodont freshwater fishes found in swamps, cave
s and some deep lakes, adapted to life in the dark. Notably, it lacks functional eye
s and pigmentation in some of the species.
in freshwater fish such as Characidae
, Cyprinidae, Gobiidae, Ostariophysi
, Poeciliidae
, Synbranchidae and to the freshwater and marine fish group Bythitidae.There are more than 80 known varieties of cavefish.
The poor food supply cave habitat, is generally a harsh environment for living, there are advantages such as a stable environment with little fluctuation, few competitors and few predators.
Adaptation common to many of the cavefish include reduced susceptibility to light, and pigment loss or reduction in the skin scales.
On the other hand, sensory organs of the body surface and the lateral line have developed chemoreceptors. There are also a pronounced adaptation in terms of energy saving, three species of cave dwelling fishes are having a more efficient metabolism during swimming compared with a group of non-cave fishes.
Also, many fish species living in the caves are having slender bodies adapted to swimming in fast-flowing waters, this trend also applies to the family Amblyopsidae.
The cave environment is dark, there is no plants performing photosynthesis, and organic food is mostly from the outside world, brought about the cave by other organisms. Chronic food shortage leads to a decrease in population density. Population density of fishes has been estimated for the Amblyopsidae to only about 0.005 to 0.15 animals per square meter.
The duration of the reproductive cycle of Amblyopsidae is very low. Breeding only once a year, occuping about 10% of the population, 40-60 have reached sexual maturity.
The eggs are large and are protected 4-5 months over the gills of the female cavity, this is considered the longest fish protection period.
Also the period growth is slower and reach sexual maturity after hatching, having a long life.
Cave fish have a limited range and the cave habitat is vulnerable to changes in the environment and is threatened by water pollution and population of the exotic species in recent years .
The Amblyopsidae family is not an exception, the World Conservation Union have placed four of the cave (IUCN) has been designated in the Red List of threatened species.
Alabama cave fish, Speoplatyrhinus poulsoni, that live only in certain caves in Alabama, is the highest risk class IA threatened, Critically Endangered
.
cave system called the Mammoth caves
. Externally, they resemble killifish
es in many respects, although their internal anatomy more closely resembles the trout-perches, with which they are currently classified. Some are deep in the swamps, and others in the lakes and streams in caves gander. These last are those with rudimentary eyes, like so many other fauna in the media devoid of light, and have the body apigmentado and translucent. The family includes a few genera and many species, quite similar.
The fish of this family are called amblyopsis by the fact that they have, at least in part, rudimentary eyes, hidden under the skin. Therefore they are blind or can only tell the difference between light and darkness. They have the naked head moderately depressed and a elongated body, covered with little cycloid irregular flakes, with tiny or absent pectoral fins and the anal opening, placed so far forward that is in the throat region.
The premaxilla, a bone of the upper jaw, is segmented, the vomer is having no teeth. They have no ventral fins, only Amblyopsis spelaea has small pelvic fins. Differently to the trout-perchs, they have not adipose fin. The lateral line is incomplete but well developed in some species. Its skeleton is having between 27-35 vertebrae.
Although some species have tiny, vestigial but functional eyes, like the two species: the springfish and the ricefish, three species have no eyes at all. Blindfishes do, however, have rows of sensory papillae on their skin, which they use to help navigate their lightless environment. The majority of cavefish have little to no pigment in their skin. Cavefishes can only be found in caves that have streams running into them; a cave with no inlets, such as Blanchard Springs Caverns
in Arkansas
, will not contain cavefishes. One species, the swampfish Chologaster cornuta
, inhabits above-ground swamps, rather than caves. A rare feature of this family is the forward placement of its cloaca
, under the head, anterior to the pelvic fins. This placement allows the females to place their eggs more precisely. This feature is present also in others species of the Percopsiformes
order, like Aphredoderidae.
They are found mostly in caves and tunnels flooded regions of the U.S., feeding on shrimp, gammarus
and arachnids falling into the water, using the vibrations of it to orient themselves to prey.
The blindfish species are blind and depigmented. Despite the lack of eyes it does respond to light and moves away from it, scotophilia.
Blindfish are generally small, ranging up to 11 centimetres (4.3 in) in length. Most do not have pelvic fins.
The Typhlichthys subterraneus
is mostly lentic, but can also be found in pools of streams near water tables. This blindfish feeds mostly on aquatic arthropods, such as amphipods
and isopods
. However, their metabolic rates are depressed in order to survive food shortages. The reproductive capabilities of this species is considerably low, with fewer than 50 eggs per female. This provides restrictions on its capabilities for recovering from an even minor population decline. When young are produced, they brood in the female's gill chamber. Sexual maturity requires approximately two years, and the life span is approximately four years.
The Forbesichthys agassizii is dark brown dorsally and fades to a creamy brown towards the pelvis
that feed primarily on micro crustaceans such as amphipods, like Gammarus troglophilus, but also prey on midge
larva
e and annelid worms
.
The Amblyopsis rosae populations lives in caves that have a relatively large source of nutrient
s, such as bat
guano
or blown leaf litter. Water quality in caves that contain cavefish is usually high. Ozark cavefish are able to tolerate the extremely low oxygen
content of ground water found in caves. Cavefish tend to occur in flowing cave streams as opposed to quiet pools. The ozark cave fish can receive nutrients with out photosynthesis or chemosynthesis, by the tree roots above the cave. The roots are full of nutrients and water. The roots are spreading photosynthesis the cave and organisms like Ozark cavefish and other species are able to feed off the roots.
Although most Amblyopsidae do not have pelvic fins, Amblyopsis spelaea has small ones with up to six rays. Like others blindfish troglodytes or abyssal
they are predator just only resulting from the lack of edible vegetation, inhabiting subterranean water or caves which have consolidated mud-rock substrates in shoals and silt-sand substrates in pools but is more often found in caves with uniform silt-sand substrates. Has low reproduction rate and broods eggs in gill cavity for up to 4-5 months. Can live for 2 years without food because of his low metabolic rate.
Many of the species are listed as threatened species in the United States and the IUCN lists the species as vulnerable, by the very restricted distribution area, and their adaptation to the shortage with a very low reproductive rate in a range of highly specialized and isolated habitat of oxigenated streams not prone to changes and competition with other species.
' is a small order that contains just nine species, grouped into three families:, Percopsidae
(trout-perches), Aphredoderidae (pirate perch) and Amblyopsidae. The family Amblyopsidae includes six species in five genera:
Family Amblyopsidae
Cave
A cave or cavern is a natural underground space large enough for a human to enter. The term applies to natural cavities some part of which is in total darkness. The word cave also includes smaller spaces like rock shelters, sea caves, and grottos.Speleology is the science of exploration and study...
s and some deep lakes, adapted to life in the dark. Notably, it lacks functional eye
Eye
Eyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement...
s and pigmentation in some of the species.
Generalities
A similar evolution to Amblyopsidae cavefishes has occurred around the world across a variety of taxa, due to convergent evolutionConvergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...
in freshwater fish such as Characidae
Characidae
The Characidae, characids or characins are a family of freshwater subtropical and tropical fish, belonging to the order Characiformes. The name "characins" is the historical one, but scientists today tend to prefer "characids" to reflect their status as a by and large monophyletic group at family...
, Cyprinidae, Gobiidae, Ostariophysi
Ostariophysi
Ostariophysi is the second-largest superorder of fish. Members of this superorder are called ostariophysians. This diverse group contains almost 8,000 species, about 28% of known fish species in the world and 68% of freshwater species, and are present on all major continents except Antarctica...
, Poeciliidae
Poeciliidae
Poeciliidae is a family of fresh-water fish which are live-bearing aquarium fish . They belong to the order Cyprinodontiformes, tooth-carps, and include well-known aquarium fish such as the guppy, molly, platy, and swordtail...
, Synbranchidae and to the freshwater and marine fish group Bythitidae.There are more than 80 known varieties of cavefish.
The poor food supply cave habitat, is generally a harsh environment for living, there are advantages such as a stable environment with little fluctuation, few competitors and few predators.
Adaptation common to many of the cavefish include reduced susceptibility to light, and pigment loss or reduction in the skin scales.
On the other hand, sensory organs of the body surface and the lateral line have developed chemoreceptors. There are also a pronounced adaptation in terms of energy saving, three species of cave dwelling fishes are having a more efficient metabolism during swimming compared with a group of non-cave fishes.
Also, many fish species living in the caves are having slender bodies adapted to swimming in fast-flowing waters, this trend also applies to the family Amblyopsidae.
The cave environment is dark, there is no plants performing photosynthesis, and organic food is mostly from the outside world, brought about the cave by other organisms. Chronic food shortage leads to a decrease in population density. Population density of fishes has been estimated for the Amblyopsidae to only about 0.005 to 0.15 animals per square meter.
The duration of the reproductive cycle of Amblyopsidae is very low. Breeding only once a year, occuping about 10% of the population, 40-60 have reached sexual maturity.
The eggs are large and are protected 4-5 months over the gills of the female cavity, this is considered the longest fish protection period.
Also the period growth is slower and reach sexual maturity after hatching, having a long life.
Cave fish have a limited range and the cave habitat is vulnerable to changes in the environment and is threatened by water pollution and population of the exotic species in recent years .
The Amblyopsidae family is not an exception, the World Conservation Union have placed four of the cave (IUCN) has been designated in the Red List of threatened species.
Alabama cave fish, Speoplatyrhinus poulsoni, that live only in certain caves in Alabama, is the highest risk class IA threatened, Critically Endangered
Critically Endangered
Critically Endangered is the highest risk category assigned by the IUCN Red List for wild species. Critically Endangered means that a species' numbers have decreased, or will decrease, by 80% within three generations....
.
Features
Probably ancient in origin, they are evolved from their aboveground counterparts. All are small and typical of the fresh waters of the southern regions of North America, significantly cave-dwelling fishes of KentuckyKentucky
The Commonwealth of Kentucky is a state located in the East Central United States of America. As classified by the United States Census Bureau, Kentucky is a Southern state, more specifically in the East South Central region. Kentucky is one of four U.S. states constituted as a commonwealth...
cave system called the Mammoth caves
Mammoth Cave National Park
Mammoth Cave National Park is a U.S. National Park in central Kentucky, encompassing portions of Mammoth Cave, the longest cave system known in the world. The official name of the system is the Mammoth-Flint Ridge Cave System for the ridge under which the cave has formed. The park was established...
. Externally, they resemble killifish
Killifish
A killifish is any of various oviparous cyprinodontiform fish . Altogether, there are some 1270 different species of killifish, the biggest family being Rivulidae, containing more than 320 species...
es in many respects, although their internal anatomy more closely resembles the trout-perches, with which they are currently classified. Some are deep in the swamps, and others in the lakes and streams in caves gander. These last are those with rudimentary eyes, like so many other fauna in the media devoid of light, and have the body apigmentado and translucent. The family includes a few genera and many species, quite similar.
The fish of this family are called amblyopsis by the fact that they have, at least in part, rudimentary eyes, hidden under the skin. Therefore they are blind or can only tell the difference between light and darkness. They have the naked head moderately depressed and a elongated body, covered with little cycloid irregular flakes, with tiny or absent pectoral fins and the anal opening, placed so far forward that is in the throat region.
The premaxilla, a bone of the upper jaw, is segmented, the vomer is having no teeth. They have no ventral fins, only Amblyopsis spelaea has small pelvic fins. Differently to the trout-perchs, they have not adipose fin. The lateral line is incomplete but well developed in some species. Its skeleton is having between 27-35 vertebrae.
Although some species have tiny, vestigial but functional eyes, like the two species: the springfish and the ricefish, three species have no eyes at all. Blindfishes do, however, have rows of sensory papillae on their skin, which they use to help navigate their lightless environment. The majority of cavefish have little to no pigment in their skin. Cavefishes can only be found in caves that have streams running into them; a cave with no inlets, such as Blanchard Springs Caverns
Blanchard Springs Caverns
Blanchard Springs Caverns is a cave system located in the Ozark National Forest in Stone County in northern Arkansas, 2 miles off Highway 14 a short distance north of Mountain View. Blanchard Springs Caverns is a three-level cave system, two of which are open for guided tours. The Dripstone Trail...
in Arkansas
Arkansas
Arkansas is a state located in the southern region of the United States. Its name is an Algonquian name of the Quapaw Indians. Arkansas shares borders with six states , and its eastern border is largely defined by the Mississippi River...
, will not contain cavefishes. One species, the swampfish Chologaster cornuta
Chologaster cornuta
Chologaster cornuta communly named Swampfish or ricefish or riceditch killifish, is a freshwater fish of the family of Amblyopsidae. It is the only living species of the genus Chologaster. It only lives in US rivers in the Atlantic Coastal Plain drainages, from southeast Virginia to central...
, inhabits above-ground swamps, rather than caves. A rare feature of this family is the forward placement of its cloaca
Cloaca
In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, reproductive, and urinary tracts of certain animal species...
, under the head, anterior to the pelvic fins. This placement allows the females to place their eggs more precisely. This feature is present also in others species of the Percopsiformes
Percopsiformes
Percopsiformes is a small order of ray-finned fish, comprising the trout-perch and its allies. It contains just nine species, grouped into three families....
order, like Aphredoderidae.
They are found mostly in caves and tunnels flooded regions of the U.S., feeding on shrimp, gammarus
Gammarus
Gammarus is an amphipod crustacean genus in the family Gammaridae. It contains more than 200 described species, making it one of the most speciose genera of crustaceans...
and arachnids falling into the water, using the vibrations of it to orient themselves to prey.
The blindfish species are blind and depigmented. Despite the lack of eyes it does respond to light and moves away from it, scotophilia.
Blindfish are generally small, ranging up to 11 centimetres (4.3 in) in length. Most do not have pelvic fins.
The Typhlichthys subterraneus
Typhlichthys subterraneus
Typhlichthys subterraneus is a species of fish in the Amblyopsidae family. It is endemic to karst regions of the eastern United States.-Taxonomy:...
is mostly lentic, but can also be found in pools of streams near water tables. This blindfish feeds mostly on aquatic arthropods, such as amphipods
Amphipoda
Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. The name amphipoda means "different-footed", and refers to the different forms of appendages, unlike isopods, where all the legs are alike. Of the 7,000 species, 5,500 are classified...
and isopods
Isopoda
Isopods are an order of peracarid crustaceans, including familiar animals such as woodlice and pill bugs. The name Isopoda derives from the Greek roots and...
. However, their metabolic rates are depressed in order to survive food shortages. The reproductive capabilities of this species is considerably low, with fewer than 50 eggs per female. This provides restrictions on its capabilities for recovering from an even minor population decline. When young are produced, they brood in the female's gill chamber. Sexual maturity requires approximately two years, and the life span is approximately four years.
The Forbesichthys agassizii is dark brown dorsally and fades to a creamy brown towards the pelvis
Pelvis
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...
that feed primarily on micro crustaceans such as amphipods, like Gammarus troglophilus, but also prey on midge
Midge
A midge is a very small, two-winged flying insect. "Midge" may also refer to:-Real:* Midge Costanza , American politician* Mildred Gillars , aka "Midge", American broadcaster of Nazi propaganda during World War II...
larva
Larva
A larva 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...
e and annelid worms
Annelid
The annelids , formally called Annelida , are a large phylum of segmented worms, with over 17,000 modern species including ragworms, earthworms and leeches...
.
The Amblyopsis rosae populations lives in caves that have a relatively large source of nutrient
Nutrient
A nutrient is a chemical that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment. They are used to build and repair tissues, regulate body processes and are converted to and used as energy...
s, such as bat
Bat
Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...
guano
Guano
Guano is the excrement of seabirds, cave dwelling bats, and seals. Guano manure is an effective fertilizer due to its high levels of phosphorus and nitrogen and also its lack of odor. It was an important source of nitrates for gunpowder...
or blown leaf litter. Water quality in caves that contain cavefish is usually high. Ozark cavefish are able to tolerate the extremely low oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
content of ground water found in caves. Cavefish tend to occur in flowing cave streams as opposed to quiet pools. The ozark cave fish can receive nutrients with out photosynthesis or chemosynthesis, by the tree roots above the cave. The roots are full of nutrients and water. The roots are spreading photosynthesis the cave and organisms like Ozark cavefish and other species are able to feed off the roots.
Although most Amblyopsidae do not have pelvic fins, Amblyopsis spelaea has small ones with up to six rays. Like others blindfish troglodytes or abyssal
Deep sea fish
Deep sea fish is a term for any fish that lives below the photic zone of the ocean. The lanternfish is, by far, the most common deep sea fish. Other deep sea fish include the flashlight fish, cookiecutter shark, bristlemouths, anglerfish, and viperfish....
they are predator just only resulting from the lack of edible vegetation, inhabiting subterranean water or caves which have consolidated mud-rock substrates in shoals and silt-sand substrates in pools but is more often found in caves with uniform silt-sand substrates. Has low reproduction rate and broods eggs in gill cavity for up to 4-5 months. Can live for 2 years without food because of his low metabolic rate.
Many of the species are listed as threatened species in the United States and the IUCN lists the species as vulnerable, by the very restricted distribution area, and their adaptation to the shortage with a very low reproductive rate in a range of highly specialized and isolated habitat of oxigenated streams not prone to changes and competition with other species.
Circadian body clocks
A new research has suggested that cavefish have unusual body clock, that does not respond to light. The still functional body clock, or circadian rhythm, is of duration 47 hours.Species
The 'PercopsiformesPercopsiformes
Percopsiformes is a small order of ray-finned fish, comprising the trout-perch and its allies. It contains just nine species, grouped into three families....
' is a small order that contains just nine species, grouped into three families:, Percopsidae
Percopsidae
Percopsidae is a family of fish in the order Percopsiformes. Its living members are two North American fresh water species of the genus Percopsis, trout-perch Percopsis omiscomaycus and sand roller Percopsis transmontana .They are small fish with weak fin spines, and an adipose fin similar to...
(trout-perches), Aphredoderidae (pirate perch) and Amblyopsidae. The family Amblyopsidae includes six species in five genera:
Family Amblyopsidae
- Genus Amblyopsis
- Amblyopsis rosae - Ozark cavefish
- Amblyopsis spelaea - Northern cavefish
- Genus Chologaster
- Chologaster cornutaChologaster cornutaChologaster cornuta communly named Swampfish or ricefish or riceditch killifish, is a freshwater fish of the family of Amblyopsidae. It is the only living species of the genus Chologaster. It only lives in US rivers in the Atlantic Coastal Plain drainages, from southeast Virginia to central...
- Swampfish
- Chologaster cornuta
- Genus Forbesichthys
- Forbesichthys agassizii - Spring cavefish
- Genus Speoplatyrhinus
- Speoplatyrhinus poulsoni - Alabama cavefish
- Genus Typhlichthys
- Typhlichthys subterraneusTyphlichthys subterraneusTyphlichthys subterraneus is a species of fish in the Amblyopsidae family. It is endemic to karst regions of the eastern United States.-Taxonomy:...
GirardCharles Frédéric GirardCharles Frédéric Girard was a French biologist specializing in ichthyology and herpetology.Born in Mulhouse, France, he studied at the College of Neuchâtel, Switzerland as a student of Louis Agassiz. In 1847, he accompanied Agassiz as his assistant to Harvard...
, 1859 - Southern cavefish
- Typhlichthys subterraneus