Percopsidae is a family of fish in the order Percopsiformes, with one extant genus with two species, both endemic to North America, two known fossil genera. They are small fish with weak fin spines, an adipose fin similar to those of trout, they feed on small crustaceans. Trout-perch article by Robert G. Bramblett Species summary Percopsis transmontana sand roller Pictures - University of Michigan
The Amblyopsidae are a fish family referred to as cavefish, blindfish, or swampfish. They are small freshwater fish found in the dark environments of caves and swamps in the eastern half of the United States. Like other troglobites, most amblyopsids exhibit adaptations to these dark environments, including the lack of functional eyes and the absence of pigmentation. More than 200 species of cavefishes are known. One of these, Forbesichthys agassizii, aboveground. A seventh species in this family, Chologaster cornuta, is not a cave-dweller but lives in aboveground swamps. Amblyopsids are small, the northern cavefish reaching up to 11 cm in length; the amblyopsids are ancient in origin. Adaptations common to many cavefish include reduced susceptibility to light, pigment loss, or reduction in skin scales, as well as development of chemoreceptors in the sensory organs of the body surface and the lateral line. Three species exhibit efficient metabolism during swimming, as compared with a group of non-cave fish, many cavefish species exhibit slender bodies adapted to swimming in fast-flowing waters.
The cave-dwellers lack pigment and are somewhat translucent. They have a naked, moderately depressed head and an elongated body, covered with small cycloid irregular flakes, with tiny or absent pelvic fins; the anal opening is so far forward. The premaxilla, a bone of the upper jaw, is segmented, the vomer has no teeth, they have no ventral fins. The lateral line is incomplete, but well developed in some species, its spine has between 35 vertebrae. Externally, they resemble killifishes in many respects, although their internal anatomy more resembles the trout-perches, with which they are classified; the name of the family, refers to their eyes. Most in this family can only detect the difference between light and darkness; the true cave-dwellers have only rudimentary eyes, like so many other fauna. Although some cave-dwellers have tiny, vestigial but functional eyes, such as the Amblyopsis and Typhlichthys have no eyes at all. Blindfish do, have rows of sensory papillae on their skin, which they use to help navigate.
Similar darkness-adaptive traits can be seen in many fish families where members live underground and is known as convergent evolution. All members of this family are small and typical of the fresh waters of the eastern and southern regions of the United States; some live deep in the swamps, others in the lakes and streams or in caves the Kentucky cave system called the Mammoth caves. Cavefish can only be found in caves. Although the cave habitat offers a poor food supply, the advantages of the environment include stable conditions, few competitors, few predators. Since the cave environment is dark, no plant life is performing photosynthesis, food is introduced from the outside world by other organisms. Limited food leads to low population density, estimated for Amblyopsidae to be only about 0.005 to 0.150 animals per square meter. Cave habitats are vulnerable to changes in the environment such as water pollution and exotic species; the Alabama cavefish, which live only in the Key Cave in Alabama, is listed as Critically Endangered by the IUCN, the highest risk class.
Cavefish breed only once a year. Members of the family Amblyopsidae lay eggs. Uniquely among fish, the genus Amblyopsis brood their eggs in the gill chambers, it was incorrectly speculated that a similar brooding behavior existed in other members of this family, as well as the pirate perch. Cavefish protect their eggs for the longest period of any fish. 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 and is present in other species of the Percopsiformes order, such as the Aphredoderidae. They feed on shrimp and arachnids that fall into the water, using vibrations and current changes to seek out their prey. Troglofauna Froese and Daniel Pauly, eds.. "Amblyopsidae" in FishBase. January 2006 version. AQUATAB. NET
The spring cavefish is the only member of the genus Forbesichthys and is one of seven species in the family Amblyopsidae. This species is listed as state endangered in Missouri, but it is considered to be of least concern by the IUCN Red List due to its large population size and number of subpopulations; the spring cavefish inhabits caves, spring runs, spring seeps. It is emerging at dusk and retreating underground an hour or two before dawn; the species is located within areas of southeastern United States. It stays underground after dawn, but emerges into surface waters at dusk, they are well adapted to their environment. The species' breeding behavior is documented. Spawning occurs underground and in darkness between April; the status and distribution of cave-obligate species is incomplete or lacking which makes conservation and management decisions difficult. Kentucky and Missouri are the two main states that have their agencies managing this species in some way. Found in a deep well in Lebanon, the spring cavefish is distributed within the central and southeastern United States.
It inhabits select springs, spring runs/seeps, caves from central and western Kentucky, west towards the Tennessee River, to south central Tennessee. It is located in areas west across southern Illinois to southeastern Missouri; the spring cavefish's distribution has decreased from within its original springs. This species is affected by the activities on the surface of the ground. Any activity that reduces water quality or quantity affects the spring cavefish, it is vulnerable to pollution from many different sources. Some of these sources include nearby agricultural fields, septic tanks, sewage lagoons, urban runoff and livestock waste; some of the springs fluctuate drastically in flow and turbidity as a result of direct connections with surface drainage or they were enclosed as water supplies or otherwise modified by man. Spring cavefish stay underground after dawn, but emerge into surface waters at dusk, they are dark brown dorsally and fade to a creamy brown towards the pelvis and reach a maximum length of 3.5 in.
The head is sloped, it has a protruding lower jaw. The fish has no pelvic adipose fin, its dorsal fin is set further back compared to most fish. This species is susceptible to developing retinoblastomas; the spring cavefish is well adapted to its environment. This system occurs in clusters on the head. Most fish detect food by sight, touch, or smell, or by a combination of these senses. Sight is important in the detection of food by most species, but this is excluded with the blind spring cavefish, they use their underdeveloped eyes to distinguish between light and darkness. However, spring cavefish cannot distinguish between edible and inedible substances by touch alone, but once in contact with the lips, the sense of taste enables the fish to distinguish among these items. Another hurdle for this species is food is lacking in their habitats, so they compensate for this scarcity of food with cannibalistic behavior. Cannibalism in the spring cavefish serves two purposes: it enables the adults to survive in an environment where food is the principal limiting factor, it serves as a means of population control.
The spring cavefish can be considered its own predator, because of the cannibalism behavior and the lack of natural predators within the caves. However, they eat a wide range of insects, small crustaceans, smaller fish, some detritus. Cave environments provide a stable habitat in terms of temperature fluctuations. However, the different species living in caves are reliant on food being brought to them by underground streams; this makes spring cavefish vulnerable to external factors as subterranean aquifers are becoming tapped for irrigation purposes, many sites may be at risk from drying out either temporarily or permanently. The breeding behavior of spring cavefish is sparsely documented. Spawning occurs underground and in darkness between April. Spring cavefish are oviparous. Females produce 100 young per female; the average spring cavefish lives for about three years and reaches a length of about 1.8 to 2.6 in. The status and distribution of cave-obligate species is incomplete or lacking which makes conservation and management decisions difficult.
This species is listed as endangered in Missouri. The IUCN Red List considers the spring cavefish to be of least concern due to its large population size and number of subpopulations; this species is declining. The Kentucky Department of Fish and Wildlife Resources is proposing to investigate the status, ecology, phylogenetic relationships, threats to populations of three cave-associated fishes in the family Amblyopsidae in Kentucky. Kentucky and Missouri are the two main states with agencies managing this species in some way. Missouri has purchased Cape LaCroix Bluffs Conservation Area to provide habitat for the state endangered spring cavefish; this 63.21-acre area supports natural wetlands, limestone bluffs, beech mesophytic forests unique to eastern Missouri
Paracanthopterygii is a superorder of fishes. Members of this group are called paracanthopterygians, it includes five orders: †Sphenocephaliformes Percopsiformes Zeiformes Stylephoriformes Gadiformes
In scientific nomenclature, a synonym is a scientific name that applies to a taxon that goes by a different scientific name, although the term is used somewhat differently in the zoological code of nomenclature. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies; this name is no longer in use: it is now a synonym of the current scientific name, Picea abies. Unlike synonyms in other contexts, in taxonomy a synonym is not interchangeable with the name of which it is a synonym. In taxonomy, synonyms have a different status. For any taxon with a particular circumscription and rank, only one scientific name is considered to be the correct one at any given time. A synonym cannot exist in isolation: it is always an alternative to a different scientific name. Given that the correct name of a taxon depends on the taxonomic viewpoint used a name, one taxonomist's synonym may be another taxonomist's correct name. Synonyms may arise whenever the same taxon is named more than once, independently.
They may arise when existing taxa are changed, as when two taxa are joined to become one, a species is moved to a different genus, a variety is moved to a different species, etc. Synonyms come about when the codes of nomenclature change, so that older names are no longer acceptable. To the general user of scientific names, in fields such as agriculture, ecology, general science, etc. A synonym is a name, used as the correct scientific name but, displaced by another scientific name, now regarded as correct, thus Oxford Dictionaries Online defines the term as "a taxonomic name which has the same application as another one, superseded and is no longer valid." In handbooks and general texts, it is useful to have synonyms mentioned as such after the current scientific name, so as to avoid confusion. For example, if the much advertised name change should go through and the scientific name of the fruit fly were changed to Sophophora melanogaster, it would be helpful if any mention of this name was accompanied by "".
Synonyms used in this way may not always meet the strict definitions of the term "synonym" in the formal rules of nomenclature which govern scientific names. Changes of scientific name have two causes: they may be taxonomic or nomenclatural. A name change may be caused by changes in the circumscription, position or rank of a taxon, representing a change in taxonomic, scientific insight. A name change may be due to purely nomenclatural reasons, that is, based on the rules of nomenclature. Speaking in general, name changes for nomenclatural reasons have become less frequent over time as the rules of nomenclature allow for names to be conserved, so as to promote stability of scientific names. In zoological nomenclature, codified in the International Code of Zoological Nomenclature, synonyms are different scientific names of the same taxonomic rank that pertain to that same taxon. For example, a particular species could, over time, have had two or more species-rank names published for it, while the same is applicable at higher ranks such as genera, orders, etc.
In each case, the earliest published name is called the senior synonym, while the name is the junior synonym. In the case where two names for the same taxon have been published the valid name is selected accorded to the principle of the first reviser such that, for example, of the names Strix scandiaca and Strix noctua, both published by Linnaeus in the same work at the same date for the taxon now determined to be the snowy owl, the epithet scandiaca has been selected as the valid name, with noctua becoming the junior synonym. One basic principle of zoological nomenclature is that the earliest published name, the senior synonym, by default takes precedence in naming rights and therefore, unless other restrictions interfere, must be used for the taxon. However, junior synonyms are still important to document, because if the earliest name cannot be used the next available junior synonym must be used for the taxon. For other purposes, if a researcher is interested in consulting or compiling all known information regarding a taxon, some of this may well have been published under names now regarded as outdated and so it is again useful to know a list of historic synonyms which may have been used for a given current taxon name.
Objective synonyms refer to taxa with same rank. This may be species-group taxa of the same rank with the same type specimen, genus-group taxa of the same rank with the same type species or if their type species are themselves objective synonyms, of family-group taxa with the same type genus, etc. In the case of subjective synonyms, there is no such shared type, so the synonymy is open to taxonomic judgement, meaning that th
Holostei are bony fish. There are eight species divided among two orders, the Amiiformes represented by a single living species, the Bowfin, the Lepisosteiformes, represented by seven living species in two genera, the gars. Further species are to be found in the fossil record and the group is regarded as paraphyletic. Holosteians are closer to teleosts than are the chondrosteans, the other group intermediate between teleosts and cartilaginous fish; the spiracles are reduced to vestigial remnants and the bones are ossified. The thick ganoid scales of the gars are more primitive than those of the bowfin. Holostei share with other non-teleost ray-finned fish a mixture of characteristics of teleosts and sharks. In comparison with the other group of non-teleost ray-finned fish, the chondrosteans, the Holostei are closer to the teleosts and further from sharks: the pair of spiracles found in sharks and chondrosteans is reduced in holosteans to a remnant structure: in gars, the spiracles do not open to the outside.
In gars, the tail is less so than in the chondrosteans. Bowfins can breathe air like the bichirs; the gars have thick ganoid scales typical of sturgeons whereas the bowfin has thin bony scales like the teleosts. The gars are therefore in this regard considered more primitive than the bowfin; the name Holostei derives from the Greek, holos meaning whole and osteon meaning bone: a reference to their bony skeletons. The cladogram shows the relationship of the Holostei to other bony fish, the great majority of which are Teleosts, to the terrestrial vertebrates that evolved from a related group of fish. Approximate dates are from al.. 2012. Holostei on The University of Liverpool website
The Carboniferous is a geologic period and system that spans 60 million years from the end of the Devonian Period 358.9 million years ago, to the beginning of the Permian Period, 298.9 Mya. The name Carboniferous means "coal-bearing" and derives from the Latin words carbō and ferō, was coined by geologists William Conybeare and William Phillips in 1822. Based on a study of the British rock succession, it was the first of the modern'system' names to be employed, reflects the fact that many coal beds were formed globally during that time; the Carboniferous is treated in North America as two geological periods, the earlier Mississippian and the Pennsylvanian. Terrestrial animal life was well established by the Carboniferous period. Amphibians were the dominant land vertebrates, of which one branch would evolve into amniotes, the first terrestrial vertebrates. Arthropods were very common, many were much larger than those of today. Vast swaths of forest covered the land, which would be laid down and become the coal beds characteristic of the Carboniferous stratigraphy evident today.
The atmospheric content of oxygen reached its highest levels in geological history during the period, 35% compared with 21% today, allowing terrestrial invertebrates to evolve to great size. The half of the period experienced glaciations, low sea level, mountain building as the continents collided to form Pangaea. A minor marine and terrestrial extinction event, the Carboniferous rainforest collapse, occurred at the end of the period, caused by climate change. In the United States the Carboniferous is broken into Mississippian and Pennsylvanian subperiods; the Mississippian is about twice as long as the Pennsylvanian, but due to the large thickness of coal-bearing deposits with Pennsylvanian ages in Europe and North America, the two subperiods were long thought to have been more or less equal in duration. In Europe the Lower Carboniferous sub-system is known as the Dinantian, comprising the Tournaisian and Visean Series, dated at 362.5-332.9 Ma, the Upper Carboniferous sub-system is known as the Silesian, comprising the Namurian and Stephanian Series, dated at 332.9-298.9 Ma.
The Silesian is contemporaneous with the late Mississippian Serpukhovian plus the Pennsylvanian. In Britain the Dinantian is traditionally known as the Carboniferous Limestone, the Namurian as the Millstone Grit, the Westphalian as the Coal Measures and Pennant Sandstone; the International Commission on Stratigraphy faunal stages from youngest to oldest, together with some of their regional subdivisions, are: A global drop in sea level at the end of the Devonian reversed early in the Carboniferous. There was a drop in south polar temperatures; these conditions had little effect in the deep tropics, where lush swamps to become coal, flourished to within 30 degrees of the northernmost glaciers. Mid-Carboniferous, a drop in sea level precipitated a major marine extinction, one that hit crinoids and ammonites hard; this sea level drop and the associated unconformity in North America separate the Mississippian subperiod from the Pennsylvanian subperiod. This happened about 323 million years ago, at the onset of the Permo-Carboniferous Glaciation.
The Carboniferous was a time of active mountain-building as the supercontinent Pangaea came together. The southern continents remained tied together in the supercontinent Gondwana, which collided with North America–Europe along the present line of eastern North America; this continental collision resulted in the Hercynian orogeny in Europe, the Alleghenian orogeny in North America. In the same time frame, much of present eastern Eurasian plate welded itself to Europe along the line of the Ural Mountains. Most of the Mesozoic supercontinent of Pangea was now assembled, although North China, South China continents were still separated from Laurasia; the Late Carboniferous Pangaea was shaped like an "O." There were two major oceans in the Carboniferous—Panthalassa and Paleo-Tethys, inside the "O" in the Carboniferous Pangaea. Other minor oceans were shrinking and closed - Rheic Ocean, the small, shallow Ural Ocean and Proto-Tethys Ocean. Average global temperatures in the Early Carboniferous Period were high: 20 °C.
However, cooling during the Middle Carboniferous reduced average global temperatures to about 12 °C. Lack of growth rings of fossilized trees suggest a lack of seasons of a tropical climate. Glaciations in Gondwana, triggered by Gondwana's southward movement, continued into the Permian and because of the lack of clear markers and breaks, the deposits of this glacial period are referred to as Permo-Carboniferous in age; the cooling and drying of the climate led to the Carboniferous Rainforest Collapse during the late Carboniferous. Tropical rainforests fragmented and were devastated by climate change. Carboniferous rocks in Europe and eastern North America consist of a repeated sequence of limestone, sandstone and coal beds. In North America, the early Carboniferous is marine