Where are Actinopterygii found?
They are found in every aquatic habitat from the abyssal depths of the ocean to freshwater streams and ponds; a few can even crawl on land for short periods of time. Ray-finned fishes constitute a major source of food for millions of people.
When did lobe-finned fish first appear?
about 450 million years agoThe lobe-finned fishes diverged from the ray-finned fishes about 450 million years ago (mya) and were highly successful during the Devonian, when hundreds of species lived in the oceans and rivers of most continents.
How long have bony fish existed?
about 419 million years agoBony fishes, class Osteichthyes, are characterised by bony skeleton rather than cartilage. They appeared in the late Silurian, about 419 million years ago.
What makes a fish Actinopterygii?
annotated classification Actinopterygii (ray-finned fishes) Fins supported by rays of dermal bone rather than by cartilage.
What was the first fish to ever exist?
The first fish were primitive jawless forms (agnathans) which appeared in the Early Cambrian, but remained generally rare until the Silurian and Devonian when they underwent a rapid evolution.
What is the difference between actinopterygii and Sarcopterygii?
Sarcopterygii and actinopterygii are two groups of osteichthyans. The key difference between sarcopterygii and actinopterygii relies mainly on their fin structure. Sarcopterygii fish species have lobed fins, while the actinopterygii fish species have ray fins.
What animal was the first to exist on earth?
SpongesThe First Animals Sponges were among the earliest animals. While chemical compounds from sponges are preserved in rocks as old as 700 million years, molecular evidence points to sponges developing even earlier.
What was the first fish to walk on land?
TiktaalikFirst Land-Walking Fish Looks Like It Had 'All-Wheel Drive' : The Two-Way Fossils of Tiktaalik, which lived some 375 million years ago and is believed to be the first fish that walked on land, had more robust hindquarters than previously known.
What is the oldest fish fossil?
Fangjinshania lived as far back as 436 million years ago, which tells us the fossil record of such sharks is much older than we previously thought.
Are most fish Actinopterygii?
By species count, actinopterygians dominate the vertebrates, and they comprise nearly 99% of the over 30,000 species of fish. They are ubiquitous throughout freshwater and marine environments from the deep sea to the highest mountain streams.
How many Actinopterygii are there?
Diversity and Lower Taxonomy: The subclass Actinopterygii comprises some 27,000 species of ray-finned bony fishes, making it the largest radiation of any vertebrate group.
How many Actinopterygii orders are there?
42 ordersThe ray-finned fishes (actinopterygians) are the largest group of living fishes and compose half of the living vertebrates. There are around 42 orders, 431 families and nearly 24,000 species.
Are fish older than dinosaurs?
Coelacanths: Fish That Predates Dinosaurs, With History Dating Back To 420 Million Years, Caught Alive.
Why are some fish so bony?
Their fine bones may help to maintain neutral buoyancy.
What percentage of fish are bony fish?
Osteichthyes includes the largest number of living species of all scientific classes of vertebrates, more than 28,000 species. Osteichthyes account for about 96% of all fish species.
Which fish is known as bony fish?
OsteichthyesOsteichthyes (/ˌɒstiːˈɪkθi. iːz/), popularly referred to as the bony fish, is a diverse taxonomic group of fish that have skeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes, which have skeletons primarily composed of cartilage.
Which order of organisms evolved from the Palaeonisciformes?
Several of the chondrostean orders developed characteristics that approached the holostean level of anatomic organization and are sometimes called subholosteans. One of these orders, the Parasemionotiformes, evolved from the Palaeonisciformes in the Early Triassic and may have given rise to at least some of the holosteans. This evolutionary line leads to the Pholidophoriformes, which gave rise to modern bony fishes, or teleosts.
When did bony fish first appear?
They first appear in the fossil record about 200 million years ago (as the family Leptolepididae), with their homocercal caudal fin and caudal skeleton already fully developed.
How do ichthyologists study fish?
In forming hypotheses about the evolution of fishes and in establishing classifications based on these hypotheses, ichthyologists place special emphasis on the comparative study of the skeleton. There are two primary advantages of this approach. First, direct comparison between extant and fossil groups is possible, the latter usually represented only by bony remains. The second advantage is that the bones of living fishes are relatively easy to observe and to study, compared with other body structures. Proper preservation and special preparation of the nervous system, for example, are difficult and expensive when the fishes being compared are from the far ends of the Earth. In the study of the relationships of species within a group, major use has been made of similarities and differences in the dimensions of external features, such as head and body length, and of counts of external characters, such as teeth, fin rays, and scales. Colour pattern is also important. In recent years, valuable data on classification of fishes have been obtained from studies of comparative behaviour, physiology, genetics and functional anatomy.
Where do bony fin rays come from?
The bony fin rays of sarcopterygians and actinopterygians probably arose from scales lying in the fin folds. Modern teleost fishes have flexible fin rays (called soft rays) of jointed segments of bone, or spiny rays, each of solid continuous bone. The first dorsal fin of acanthopterygian fishes is of the spiny type.
When did the Chondrostei go extinct?
The Chondrostei may have first arisen as early as the Early Devonian, increased in numbers and complexity until about the Permian, and thereafter declined, becoming almost extinct by the middle of the Cretaceous, 100 million years ago.
Why is the tail of a fish not an effective swimming organ?
The original tail fin of primitive fishes was not an effective swimming organ, because of its asymmetry. The steady improvement in tail shape over 400 million years is one of the prominent features of fish evolution. In primitive fishes the tail (vertebral) axis turned upward (heterocercal) or downward (hypocercal), ...
When did the Actinopterygians first appear?
Actinopterygian fossils first appeared in deposits from the late Silurian (425 to 405 Ma) or early Devonian (405 to 345 Ma) period. While there is a need for more research to understand the evolutionary relationships among the earliest actinopterygians, ichthyologists have found that actinopterygians did not begin to dominate the fish fauna until the beginning of the Carboniferous period, 360 million years ago (Ma). The most derived forms (i.e. teleosts) were uncommon until the late Cretaceous (144 to 65 Mz) period. It was at this time that major diversification began and has continued to this day, as actinopterygians dominate the world’s fish fauna. ( Grande, 1998; Helfman, et al., 1997; Moyle and Cech, 2004)
How many species of actinopterygians are there?
The truly spectacular array of body forms within this class can only be appreciated by familiarizing oneself with some of the more than 25,000 species of actinopterygians – the largest and most diverse of all vertebrate classes – that exist today. Consider the fact that actinopterygians may fly, walk, or remain immobile (in addition to 'swimming'), exist in virtually all types of habitats except constantly dry land (though some can walk over land), feed on nearly every type of organic matter, utilize several types of sensory systems (including chemoreception, electroreception, magnetic reception and a “distance-touch” sensation – see Communication), and some even produce their own light or electricity. In addition, color diversity in ray-finned fishes is “essentially unlimited, ranging from uniformly dark black or red in many deepsea forms, to silvery in pelagic and water-column fishes, to countershaded in nearshore fishes of most littoral [near-shore] communities, to the strikingly contrasted colors of tropical freshwater and marine fishes” (Helfman et al. 1997:367). Of course, extravagant coloration is not helpful for fish at risk of being eaten, yet bright coloration is environment-specific (see Helfman et al. 1997:367) and bright colors at one depth are cryptic at others due to light attenuation (see Communication). Further, color change is common in brightly colored (as well as many other) fishes and occurs under a variety of circumstances. Pigments are responsible for a many types of color change, but there are also structural colors, resulting from light reflecting off of crystalline molecules housed in special chromatophores (cells located mainly in the outer layer of skin). The silvery sheen displayed by many pelagic fishes is an example of structural color. Numerous actinopterygians are also sexually dimorphic (males and females look different), and body form changes drastically during development, so there is significant diversity within, as well as among, species. ( Berra, 2001; Bertelson and Pietsch, 1998; Helfman, et al., 1997; Moyle and Cech, 2004; Paxton, 1998)
Why do ray finned fish migrate?
Many ray-finned fishes exhibit migratory behavior; daily migrations are usually related to feeding or predator avoidance while longer migrations are usually for reproduction purposes. Some fishes stay within saltwater ( oceanodromous) or fresh water ( potamodromous) their entire lives, while others migrate between the salt and fresh water as part of their life cycle (e.g. to reproduce) or to feed ( diadromous ). Diadromous species can be broken down into three types: those in which growth occurs primarily in saltwater but move into freshwater to spawn (termed anadromous) – e.g. salmon; those in which growth occurs primarily in freshwater but move into saltwater to spawn (termed catadromous) – e.g. anguillid eels; and those that migrate between salt and fresh water for purposes other than spawning, such as feeding (termed amphidromous) – e.g. various gobies , sleepers and galaxiids. While many ray-finned fishes migrate well outside their home range – in many cases hundreds of kilometers, against current and even up waterfalls – they have remarkable abilities to find their way back. For instance, salmon can remember the odor of the rivers they originated from, as well as the odor of other rivers they have passed during migration. In addition, salmon (among other actinopterygians) use currents, salinity and temperature gradients, and topographic cues (buoys or islands) for orientation. Tidepool sculpins separated from their home pool by 100 m can also find their way back using olfactory and visual cues. While younger fish rely on visual or olfactory cues, some older fish, even if removed from their original locale for multiple years, only require visual cues, utilizing a cognitive map to navigate. ( Helfman, et al., 1997; Moyle and Cech, 2004; Paxton, 1998)
What are the phylogenetic trends of early actinopterygians?
The phylogenetic trends within early actinopterygians provide a basis for understanding why this group has been so successful, as more derived forms (i.e. neopterygians and teleosts ), which make up nearly all existing ray-finned fishes, have repeated and extended early trends.
How many developmental periods are there in fish?
In general, five major developmental periods are recognized in fish: embryonic, larval, juvenile, adult, and senescent. Fish development is known for its confounding terminology, so there are many gray areas within these major categories, and, as with many other animals, many species tend to defy classification into discrete categories. For instance, species in several teleostean families bear live young (viviparous) – Poeciliidae, Scorpaenidae, and Embiotocidae (to name a few), and the young in some families ( Salmonidae) seem to emerge as juveniles after hatching (externally) from the egg. ( Moyle and Cech, 2004)
How long does it take for a coral reef fish to hatch?
It is important to note that the young of reef fishes develop quite differently from most temperate fishes that have been studied. While the eggs of most temperate fishes hatch from 3 to 20 days after laying, the eggs of most coral reef species hatch within only a day. Also, at any given size, the larvae of reef fishes are more developed than most temperate, non- perciform fish: they have "more complete fins, develop scales at smaller size, [have] seemingly better sensory apparatus at any size, and are morphologically equipped for effective feeding within a few days of hatching" (173). Finally, the settling habitat for reef fishes (coral reefs) tends to be relatively fragmented and, therefore, much more difficult to locate, unlike the habitat of temperate fishes, which tends to have large expanses suitable for settling. This brief glimpse into the pelagic stage of reef fishes reveals the diversity and complexity of development in actinopterygians. ( Lies and McCormick, 2002)
What is an actinopterygii?
Actinopterygii. Actinopterygii includes a remarkably diverse assemblage of fishes, including more than half of the living species of known vertebrates; From: Encyclopedia of Biodiversity, 2001. Download as PDF.
What is the most common ancestor of Actinopterygii?
Osteichthyes is defined as the most recent common ancestor of Actinopterygii and Sarcopterygii, and all of that ancestor's descendants. Osteichthyes is diagnosed by the presence of lungs (see below) and by most of the bony skeleton being formed from cartilaginous precursors. Many bony fishes have an elongated sac, the gas bladder, situated dorsal to the digestive tract. Gas bladders can serve either a buoyancy control function (swim bladder) or a gas exchange function (respiratory gas bladder). In the latter condition, they are highly vascularized and serve as a supplementary reserve for oxygen to be used in respiration. Although gas bladders and lungs differ in their position relative to the digestive tract (lungs are ventral to the digestive tract) and lungs tend to be paired while gas bladders are single, their developmental origins and gross anatomical features are quite similar. These similarities provide some evidence that the two structures are homologous. Actinopterygii includes a remarkably diverse assemblage of fishes, including more than half of the living species of known vertebrates; over 24,000 valid species are known (see Eschmeyer, 1998 ). The skeleton of actinopterygians is extensively ossified and the internal pectoral skeleton has broad bony plates that facilitate support of fin rays.
What are the two classes of Actinopterygii?
The Actinopterygii are divided into two classes: Cladistia (bichirs), represented by a single modern order (Polypteriformes) restricted to Africa, and Actinopteri, with the subclasses Chondrostei and Neopterygii. Only the subclass Neopterygii occurs in South and Central America, branched in two infraclasses, Holostei and Teleostei. The Holostei (gars) are secondary freshwater fish with only eight modern species, three of the genus Atractosteus, family Lepisosteidae, occurring in Central America. There are four major groups within Teleostei: Elopomorpha, Osteoglossomorpha, Otomorpha, and Euteleosteomorpha ( Fig. 1.4 ).
What are the clupei and ostariophysi?
Three synapomorphies define the group ( Arratia, 1999 ): the medial extrascapular fused to the parietal or fused to the parietal and supraoccipital; autopalatine ossifying early on ontogeny; and bases of hipural 1 and 2 not united by cartilage at any stage of growth. Clupeomorpha includes the Clupeiformes, and Ostariophysi includes the Gonorynchiformes and the Otophysa with four orders: Cypriniformes, Characiformes, Siluriformes, and Gymnotiformes. The Alepocephali was tentatively included as a third subcohort of the Otomorpha based on molecular studies, but so far no morphological synapomorphies have been found to support this hypothesis ( Betancur et al., 2017 ).
How long is a leptocephalous larva?
As a ribbon and commonly 10 cm long, but reaching up to 2 m, the larva shrinks during metamorphosis into the juvenile form.
What is a ray-finned fish?
13.3.1.1 Ray-finned fish— (Actinopterygii) Ray-finned ( Actinopterygii) fish are named after their fins that are supported by rays of bony spines that in turn are supported by bony spines rather than the fleshy alternatives of the lobed-finned fishes.
Where are Neopterygii found?
Only the subclass Neopterygii occurs in South and Central America, branched in two infraclasses, Holostei and Teleostei. The Holostei (gars) are secondary freshwater fish with only eight modern species, three of the genus Atractosteus, family Lepisosteidae, occurring in Central America. There are four major groups within Teleostei: Elopomorpha, ...
What is the fossil record of Actinopterygii?
Actinopterygii. : Fossil Record. The fishes that dominated much of the Mesozoic were once classified in another paraphyletic grouping -- the holosteans. This group included a number of lineages, including relatives of today's gars and bowfins.
What is the name of the earliest teleost?
Aspidorhynchus at the right, also from the Solnhofen Limestone, was one of these earliest teleosts; note the long snout, which is typical of Aspidorhynchus and its kin. By the beginning of the Cenozoic, the teleosts were the dominant fish in the world's waters.