40-526: Ammocrypta is a genus of freshwater ray-finned fish , commonly known as the sand darters , which is classified in the subfamily Etheostomatinae , part of the family Percidae which also includes the perches , ruffes and pikeperches . The species in the genus occur in eastern North America in Canada and the continental United States . Ammocrypta species are characterised by having rather elongate and slender bodies. Their bodies are translucent and there
80-424: A backbone or spine, consisting of vertebrae and intervertebral discs , and a cranium , or skull. The vertebrae are irregular bones , and the intervertebral discs are of fibrocartilage . The vertebral column surrounds and protects the spinal cord , while the cranium protects the brain . The vertebrates make up the subphylum Vertebrata with some 65,000 species in the phylum Chordata . They evolved in
120-437: A phylum characterised by a notochord , a hollow nerve cord along the back , and pharyngeal gills arranged in pairs. As embryos, vertebrates still have a notochord; as adults, all but the jawless fishes have a vertebral column, made of bone or cartilage , instead. Vertebrate embryos have pharyngeal arches ; in adult fish , these support the gills , while in adult tetrapods they develop into other structures. In
160-587: A subgenus of Ammocrypta . Ray-finned fish Actinopterygii ( / ˌ æ k t ɪ n ɒ p t ə ˈ r ɪ dʒ i aɪ / ; from actino- 'having rays' and Ancient Greek πτέρυξ (ptérux) 'wing, fins'), members of which are known as ray-finned fish or actinopterygians , is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of skin supported by radially extended thin bony spines called lepidotrichia , as opposed to
200-459: A free-swimming larval stage. However other patterns of ontogeny exist, with one of the commonest being sequential hermaphroditism . In most cases this involves protogyny , fish starting life as females and converting to males at some stage, triggered by some internal or external factor. Protandry , where a fish converts from male to female, is much less common than protogyny. Most families use external rather than internal fertilization . Of
240-726: A trait still present in Holostei ( bowfins and gars ). In some fish like the arapaima , the swim bladder has been modified for breathing air again, and in other lineages it have been completely lost. The teleosts have urinary and reproductive tracts that are fully separated, while the Chondrostei have common urogenital ducts, and partially connected ducts are found in Cladistia and Holostei. Ray-finned fishes have many different types of scales ; but all teleosts have leptoid scales . The outer part of these scales fan out with bony ridges, while
280-540: Is divided into the infraclasses Holostei and Teleostei . During the Mesozoic ( Triassic , Jurassic , Cretaceous ) and Cenozoic the teleosts in particular diversified widely. As a result, 96% of living fish species are teleosts (40% of all fish species belong to the teleost subgroup Acanthomorpha ), while all other groups of actinopterygians represent depauperate lineages. The classification of ray-finned fishes can be summarized as follows: The cladogram below shows
320-557: Is only a single spine in the anal fin . They also have Spreitzer vertebrae , that is that the first three vertebrae of the backbone, counting from the head, have an open haemal arch which allows for the fish's kidney to expand. They have the habit of burying into the sand or gravel bed of streams, only their eyes being visible. The translucence of their bodies and their habit of burying themselves gives them some protection against predation. The shared morphological characteristics of Ammocrypta with its sister taxon Crystallaria include
360-432: Is relatively rare and is found in about 6% of living teleost species; male care is far more common than female care. Male territoriality "preadapts" a species for evolving male parental care. There are a few examples of fish that self-fertilise. The mangrove rivulus is an amphibious, simultaneous hermaphrodite, producing both eggs and spawn and having internal fertilisation. This mode of reproduction may be related to
400-642: Is strongly supported by two CSIs found in the proteins Rrp44 (associated with the exosome complex ) and serine C-palmitoyltransferase . These are exclusively shared by species from these two subphyla, but not by cephalochordates. Conventional classification groups extant vertebrates into seven classes based on traditional interpretations of gross anatomical and physiological traits. The commonly held classification lists three classes of fish and four of tetrapods . In addition to these, there are two classes of extinct armoured fishes, Placodermi and Acanthodii , both paraphyletic . Other ways of classifying
440-512: The Bilateria , a group of animals with mirror symmetrical bodies. They move, typically by swimming, using muscles along the back, supported by a strong but flexible skeletal structure, the spine or vertebral column . The name 'vertebrate' derives from the Latin vertebratus ("jointed"), from vertebra , "joint", in turn from Latin vertere to turn. Vertebrates belong to the chordates ,
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#1733085946596480-565: The Cambrian period, over 500 million years ago. The vertebrates include mammals , birds , amphibians , and various classes of reptiles and fish . Classes of fish include the jawless Agnatha , and the jawed Gnathostomata . The jawed fish include both the cartilaginous fish and the bony fish . Bony fish include the lobe-finned fish , which gave rise to the tetrapods , the animals with four limbs. Vertebrates make up less than five percent of all described animal species . Vertebrates belong to
520-732: The Cenozoic , the current era, great diversification of ray-finned fishes , amphibians, reptiles, birds and mammals has taken place. It is sometimes called the Age of Mammals, because of the dominance of the terrestrial environment by that group. Placental mammals have occupied the Northern Hemisphere, with marsupial mammals in the Southern Hemisphere. Molecular markers known as conserved signature indels (CSIs) in protein sequences have been identified and provide distinguishing criteria for
560-500: The Cyprinidae (in goldfish and common carp as recently as 14 million years ago). Ray-finned fish vary in size and shape, in their feeding specializations, and in the number and arrangement of their ray-fins. In nearly all ray-finned fish, the sexes are separate, and in most species the females spawn eggs that are fertilized externally, typically with the male inseminating the eggs after they are laid. Development then proceeds with
600-576: The Devonian period , often known as the "Age of Fishes". The two groups of bony fishes , Actinopterygii and Sarcopterygii , evolved and became common. By the middle of the Devonian, a lineage of sarcopterygii left the water, establishing themselves as amphibians , terrestrial tetrapod vertebrates, in the next geological period, the Carboniferous . Amniotes branched from amphibious tetrapods early in
640-518: The Ohio River , the Lake St Clair system as well as the lower drainage basins of Lake Huron and Lake Superior . The currently recognized species in this genus are: Ammocrypta is the sister taxon of the genus Crystallaria and together these genera are the sister taxon of the clade consisting of the speciose genus Etheostoma and Nothonotus . Some authorities regard Crystallaria as
680-481: The oviparous teleosts, most (79%) do not provide parental care. Viviparity , ovoviviparity , or some form of parental care for eggs, whether by the male, the female, or both parents is seen in a significant fraction (21%) of the 422 teleost families; no care is likely the ancestral condition. The oldest case of viviparity in ray-finned fish is found in Middle Triassic species of † Saurichthys . Viviparity
720-651: The sister lineage of all other actinopterygians, the Acipenseriformes (sturgeons and paddlefishes) are the sister lineage of Neopterygii, and Holostei (bowfin and gars) are the sister lineage of teleosts. The Elopomorpha ( eels and tarpons ) appear to be the most basal teleosts. The earliest known fossil actinopterygian is Andreolepis hedei , dating back 420 million years ( Late Silurian ), remains of which have been found in Russia , Sweden , and Estonia . Crown group actinopterygians most likely originated near
760-568: The Carboniferous period. The synapsid amniotes were dominant during the late Paleozoic, the Permian , while diapsid amniotes became dominant during the Mesozoic . In the sea, the teleosts and sharks became dominant. Mesothermic synapsids called cynodonts gave rise to endothermic mammals and diapsids called dinosaurs eventually gave rise to endothermic birds , both in the Jurassic . During
800-1034: The Devonian-Carboniferous boundary. The earliest fossil relatives of modern teleosts are from the Triassic period ( Prohalecites , Pholidophorus ), although it is suspected that teleosts originated already during the Paleozoic Era . The listing below is a summary of all extinct (indicated by a dagger , †) and living groups of Actinopterygii with their respective taxonomic rank . The taxonomy follows Phylogenetic Classification of Bony Fishes with notes when this differs from Nelson, ITIS and FishBase and extinct groups from Van der Laan 2016 and Xu 2021. [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] Vertebrata Ossea Batsch, 1788 Vertebrates ( / ˈ v ɜːr t ə b r ɪ t s , - ˌ b r eɪ t s / ) are animals with
840-402: The adjacent diagram. The swim bladder is a more derived structure and used for buoyancy . Except from the bichirs , which just like the lungs of lobe-finned fish have retained the ancestral condition of ventral budding from the foregut , the swim bladder in ray-finned fishes derives from a dorsal bud above the foregut. In early forms the swim bladder could still be used for breathing,
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#1733085946596880-459: The basic vertebrate body plan: a notochord, rudimentary vertebrae, and a well-defined head and tail, but lacked jaws. A vertebrate group of uncertain phylogeny, small eel-like conodonts , are known from microfossils of their paired tooth segments from the late Cambrian to the end of the Triassic. The first jawed vertebrates may have appeared in the late Ordovician (~445 mya) and became common in
920-463: The bichirs and holosteans (bowfin and gars) in having gone through a whole-genome duplication ( paleopolyploidy ). The WGD is estimated to have happened about 320 million years ago in the teleosts, which on average has retained about 17% of the gene duplicates, and around 180 (124–225) million years ago in the chondrosteans. It has since happened again in some teleost lineages, like Salmonidae (80–100 million years ago) and several times independently within
960-440: The bulkier, fleshy lobed fins of the sister class Sarcopterygii (lobe-finned fish). Resembling folding fans , the actinopterygian fins can easily change shape and wetted area , providing superior thrust-to-weight ratios per movement compared to sarcopterygian and chondrichthyian fins. The fin rays attach directly to the proximal or basal skeletal elements, the radials, which represent the articulation between these fins and
1000-691: The conventional interpretations of their anatomy and physiology. It was once thought that the Cephalochordata was the sister taxon to Vertebrata. This group, Notochordata, was taken to be sister to the Tunicata (the Notochordata hypothesis). Since 2006, analysis has shown that the tunicates + vertebrates form a clade, the Olfactores, with Cephalochordata as its sister (the Olfactores hypothesis ), as shown in
1040-706: The different actinopterygian clades (in millions of years , mya) are from Near et al., 2012. Jaw-less fishes ( hagfish , lampreys ) [REDACTED] Cartilaginous fishes ( sharks , rays , ratfish ) [REDACTED] Coelacanths [REDACTED] Lungfish [REDACTED] Amphibians [REDACTED] Mammals [REDACTED] Sauropsids ( reptiles , birds ) [REDACTED] Polypteriformes ( bichirs , reedfishes ) [REDACTED] Acipenseriformes ( sturgeons , paddlefishes ) [REDACTED] Teleostei [REDACTED] Amiiformes ( bowfins ) [REDACTED] Lepisosteiformes ( gars ) [REDACTED] The polypterids (bichirs and reedfish) are
1080-403: The embryo , a layer of cells along the back folds and fuses into a hollow neural tube . This develops into the spinal cord , and at its front end, the brain . The brain receives information about the world through nerves which carry signals from sense organs in the skin and body. Because the ancestors of vertebrates usually moved forwards, the front of the body encountered stimuli before
1120-437: The end of the body. The ancestral vertebrates, and most extant species, are aquatic and carry out gas exchange in their gills. The gills are finely-branched structures which bring the blood close to the water. They are positioned just behind the head, supported by cartilaginous or bony branchial arches . In jawed vertebrates , the first gill arch pair evolved into the jaws. In amphibians and some primitive bony fishes,
1160-515: The first reptiles include modern reptiles, mammals and birds; the agnathans have given rise to the jawed vertebrates; the bony fishes have given rise to the land vertebrates ; the traditional " amphibians " have given rise to the reptiles (traditionally including the mammal-like synapsids), which in turn have given rise to the mammals and birds. Most scientists working with vertebrates use a classification based purely on phylogeny, organized by their known evolutionary history and sometimes disregarding
1200-432: The fish's habit of spending long periods out of water in the mangrove forests it inhabits. Males are occasionally produced at temperatures below 19 °C (66 °F) and can fertilise eggs that are then spawned by the female. This maintains genetic variability in a species that is otherwise highly inbred. Actinopterygii is divided into the subclasses Cladistia , Chondrostei and Neopterygii . The Neopterygii , in turn,
1240-494: The highest mountain streams . Extant species can range in size from Paedocypris , at 8 mm (0.3 in); to the massive ocean sunfish , at 2,300 kg (5,070 lb); and to the giant oarfish , at 11 m (36 ft). The largest ever known ray-finned fish, the extinct Leedsichthys from the Jurassic , has been estimated to have grown to 16.5 m (54 ft). Ray-finned fishes occur in many variant forms. The main features of typical ray-finned fish are shown in
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1280-438: The inner part is crossed with fibrous connective tissue. Leptoid scales are thinner and more transparent than other types of scales, and lack the hardened enamel - or dentine -like layers found in the scales of many other fish. Unlike ganoid scales , which are found in non-teleost actinopterygians, new scales are added in concentric layers as the fish grows. Teleosts and chondrosteans (sturgeons and paddlefish) also differ from
1320-425: The internal skeleton (e.g., pelvic and pectoral girdles). The vast majority of actinopterygians are teleosts . By species count, they dominate the subphylum Vertebrata , and constitute nearly 99% of the over 30,000 extant species of fish . They are the most abundant nektonic aquatic animals and are ubiquitous throughout freshwater and marine environments from the deep sea to subterranean waters to
1360-438: The larvae have external gills , branching off from the gill arches. The tetrapods have lost the gills of their fish ancestors; they have adapted the swim bladder (that fish use for buoyancy) into lungs to breathe air. At the same time, they adapted the bony fins of the lobe-finned fishes into two pairs of walking legs , carrying the weight of the body via the shoulder and pelvic girdles . Vertebrates vary in size from
1400-411: The main clades of living actinopterygians and their evolutionary relationships to other extant groups of fishes and the four-limbed vertebrates ( tetrapods ). The latter include mostly terrestrial species but also groups that became secondarily aquatic (e.g. whales and dolphins ). Tetrapods evolved from a group of bony fish during the Devonian period . Approximate divergence dates for
1440-513: The possession of complete lateral lines and unbroken canal on the head. They also share high meristic counts which are thought to be indications of basal morphology, referred to as plesiomorphies . Ammocrypta is found in eastern North America where thy are found across the central part of the coastal plain of the Gulf of Mexico , the whole of the drainage basin of the Mississippi River and of
1480-409: The rest of the body, favouring cephalisation , the evolution of a head containing sense organs and a brain to process the sensory information. Vertebrates have a tubular gut that extends from the mouth to the anus . The vertebral column typically continues beyond the anus to form an elongated tail . This means that (unlike in some invertebrates like annelid worms) the anus is not usually at
1520-715: The smallest frog species such as Brachycephalus pulex , with a minimum adult snout–vent length of 6.45 millimetres (0.254 in) to the blue whale , at up to 33 m (108 ft) and weighing some 150 tonnes. Vertebrates originated during the Cambrian explosion at the start of the Paleozoic, which saw a rise in animal diversity. The earliest known vertebrates belong to the Chengjiang biota and lived about 518 million years ago. These include Haikouichthys , Myllokunmingia , Zhongjianichthys , and probably Yunnanozoon . Unlike other Cambrian animals, these groups had
1560-404: The vertebrate subphylum. Specifically, five CSIs in the following proteins: protein synthesis elongation factor-2 , eukaryotic translation initiation factor 3 , adenosine kinase and a protein related to ubiquitin carboxyl-terminal hydrolase are exclusively shared by all vertebrates and reliably distinguish them from all other animals. A specific relationship between vertebrates and tunicates
1600-438: The vertebrates have been devised, particularly with emphasis on the phylogeny of early amphibians and reptiles. An example based on Janvier (1981, 1997), Shu et al. (2003), and Benton (2004) is given here († = extinct ): While this traditional classification is orderly, most of the groups are paraphyletic, meaning that the classification does not accurately reflect the natural evolved grouping. For instance, descendants of
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