Infraclass Teleostei: “Teleosts”  The vast majority of modern fishes are “teleosts.”  They have replaced the heavy, armored scales of their ancestors with much lighter more flexible scales that overlap each other and also have evolved homocercal symmetrical tails.

Class Actinopterygii Subclass Chondrostei [37 species] Order Acipenseriformes (paddlefish and sturgeons) Order Polypteriformes (bichirs) Subclass Neopterygii Infraclass Holostei [8 species] Infraclass Teleostei Order Lepisosteiformes (gars) Order Amiiformes (bowfin) 12 superorders

Teleosts  The teleosts are extremely abundant and have diversified into an enormous number of species (depending on authority about 24,000 species).  They represent about half of all vertebrate species and have colonized all marine and freshwater habitats from -11,000 m to +4,500m and occupy water that ranges in temperature from polar (-1.8ºC) to hot springs (43ºC).

Teleost characters  Homocercal tail  Circular scales without ganoine  Ossified vertebrae  Swim bladder – structure and function discussed previously.  Skull with complex jaw mobility

Jaw mobility in teleosts  The skull in teleosts has become greatly lightened from the much more robustly constructed skull of the holosteans and is much more flexible.  Bones in the upper jaw, which were once firmly fixed to the skull and had teeth have become more loosely attached and teeth are often absent.

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Jaw mobility in teleosts  The maxillary bone (on the upper jaw) is mobile in teleosts [and in bowfins, but not gars].  In addition the premaxillary bone (which is anterior to the maxilla) is also mobile.

Jaw mobility in teleosts  This mobility in the upper jaws has contributed to a major development in the teleosts, which is the conversion of jaws from simple devices for grasping to sophisticated suction devices.  An approaching fish can push prey away just as your hand does when you reach for something underwater, but a rapid expansion of the orobranchial cavity creates a flow of water into the fishes mouth.

Jaw mobility in teleosts  The mobility of the maxilla and premaxilla allows the upper jaw to extend and protrude from the mouth.  Jaw protrusion is achieved by levering forward the premaxilla from behind.  The premaxilla is attached with ligaments that allow the bone to slide forward on top of the skull.

Jaw mobility in teleosts  In a feeding fish this protrusion is accompanied by other movements of the orobranchial cavity [mouth and gill cavities], the head is raised, jaw lowered and the opercula are moved laterally.  The net result of all these movements is a sudden expansion of the volume of the oral cavity that quickly sucks water (and prey) into the mouth.

Lake Victoria cichlid

Jaw mobility in teleosts  Based on anatomical comparisons of their structure in different groups it is clear that protrusible jaws have evolved independently multiple in different teleost clades.  Jaw protrusion is widespread among the perciform fishes, but also occurs in silversides, cods and anglerfishes, and in minnows.

Pharyngeal Jaws  Mobile and often powerful pharyngeal jaws have evolved several times in actinopterygians.  Ancestral ray finned fishes possessed many dermal tooth plates within the pharynx. Some toothplates over time became fused together and to parts of some gill arches.

Pharyngeal jaws  The earliest pharyngeal jaws were not very mobile, but could be used to hold prey before swallowing. Today a variety of pharyngeal jaws occur in different groups.  For example, in minnows the primary jaws lack teeth but the pharyngeal jaws are enlarged and close against a horny pad on the base of the skull. They are used to grind plant material.

Pharyngeal jaws  In many groups the upper and lower pharyngeal jaws can move independently of each other.  For example, in some moray eels the pharyngeal jaws can be extended from the throat into the oral cavity to grasp prey and pull it into the throat and esophagus.

These X-rays show the normal position of the pharyngeal jaws (upper), and how they can move forward into the mouth to seize food (lower). (Credit: Rita Mehta, Section of Evolution and Ecology and Candi Stafford, School of Veterinary Medicine, UC Davis.) Legend pasted from eleases/2007/09/ htm

Moray Eel Pharyngeal jaws

Pharyngeal jaws  The cichlids of Lakes Victoria, Malawi and Tanganyika have diversified enormously into about 500 species in a period of only about 14,000 years.  The possession of pharyngeal jaws which can process food has allowed the outer jaws to be greatly modified to consume a wide variety of prey. Foods consumed include, other fish, plankton, algae, fish scales, bivalves, and diatoms.

Teleost classification  How the Neopterygii should be subdivided differs greatly from authority to authority.  We will use a recent classification that divides the teleosts into a dozen superorders (some very large)

Infraclass Teleostei Superorder Elopomorpha [eels, tarpon, bonefish] Superorder Clupeomorpha [herrings, anchovies] Superorder Ostariophysi [carp, piranha, catfishes, electric eels] Superorder Paracanthopterygia [cod, anglerfish, toadfish] Superorder Protacanthopterygii [salmon, pike] Superorder Acanthopterygi [perch, tuna mackeral] Five other superorders of relatively small numbers of fishes Superorder Osteoglossomorpha [elephant fishes, Arapaima]

Infraclass Teleostei Superorder Stenopterygii [jellynose fish, hatchet fishes] Superorder Cyclosquamata [Bombay duck, lancetfishes] Superorder Scopelomorpha [lanternfishes] Superorder Lampridiomorpha [oarfish, ribbonfishes] Superorder Polymixiomorpha [beardfishes] The other five superorders

Superorder Elopomorpha  Elopomorpha: includes tarpons, bonefishes, and eels.  Specialized laterally compressed and transparent leptocephalous [Greek slim headed] larvae are a unique feature of the group.  Unlike most fish larvae they grow large (6-30cm) and are good swimmers.  They have a long larval life of 3 months to a year adrift on the ocean being moved by ocean currents.

Eel leptocephalus larvae

Bonefish Tarpon fishn/Tarpon-FISH-Justin- S-America-Venezuela-Los-Rogos.jpg

Tarpons  There are two species of tarpon, one found in the Atlantic and Caribbean (“the” tarpon or Atlantic tarpon) and the Indo-Pacific tarpon.  One of the most popular of game fishes they grow 5-8’ in length and weigh lbs. They put up a tremendous fight when hooked and will leap high from the water. Generally caught and released as they don’t taste great.  An ocean fish, but tolerant of brackish and even freshwater. The swim-bladder serves as an accessory breathing organ and this enables tarpon to tolerate low- oxygen conditions.

Eels  Most elopomorphs are eel-like and marine, but some tolerate freshwater.  The American eel has a very unusual life- cycle. The eels grow to sexual maturity in rivers and streams (taking 10 years or more) and then migrate downriver into the ocean to breed. (They are catadramous.)

Eels  They swim to the Sargasso Sea (an area of the North Atlantic between the Azores and West Indies) where they apparently spawn and die, presumably at depth.  Eggs and larvae float to the surface and drift on the currents until they reach the near the coast. Then they transform into miniature eels and travel up rivers to mature.

American Eel Anguilla-rostrata-2.jpg Eel larvae

Eels  European eels also spawn in the Sargasso Sea. Their larvae travel on clockwise currents mainly of the Gulf Stream and are distributed to North Africa, Northern Europe, the Mediterranean and as far as the Black Sea.  Because they drift in cooler waters, European eels grow more slowly than American eels. Development is slowed less than growth however, and as a result European eels have more vertebrae than American eels.

Superorder Clupeomorpha  Are a commercially very important group of about 360 species of mostly marine schooling, silvery fishes.  They include herring, shad, pilchards, anchovies and sardines and schools can be enormous and provide an important food source for many larger marine predators including sharks and dolphins.  They feed on plankton which they gather using a specialized mouth and gill-straining apparatus. Teeth are small or absent.

Superorder Clupeomorpha  Clupeomorphs lack a lateral line and are physostomous, which means there is a direct connection between the swim bladder and the gut.  Most are quite small -- size range is from 2 to 75cm.

Herring

Reef fish attacking a school of Pacific herring  HjVe0 HjVe0 HjVe0

Superorder Ostariophysi  Ostariophysi (from Greek for bone and bladder).  The second-largest superorder of fish and includes about 28% of all living fishes and almost 70% of freshwater species. Total number of species is estimated at about 7900 species. Worldwide distribution except for Antarctica and New Zealand.  Catfish, Cyprinids [minnows and carp], electric eels, piranhas.  Display very diverse traits, but many have protrusible jaws and pharyngeal teeth act as second jaws.

Superorder Ostariophysi  Members of the group possess two unique derived features: alarm substances in the skin and alarm substances in the skin and the Weberian apparatus. the Weberian apparatus.  When the skin is damaged, pheromones are released into the water and these stimulate a fright reaction in other members of the species and other ostariophysians. In response, they may quickly seek cover or school together.

Weberian Apparatus  Weberian apparatus: The name ostariophysian (Greek: bone and bladder) refers to a series of small bones that connect the swim bladder with the inner ear.  The Weberian apparatus greatly enhances hearing in these fish and as a result they are more sensitive to sounds and can hear a wider range of sounds than other fishes.

Weberian apparatus  When sound waves strike the swimbladder it vibrates.  A bone (the tripus) in contact with the swim bladder then conducts this vibration via ligaments to two other bones, the second of which moves and compresses a section of the inner ear against a fourth bone.  This fourth bone (the claustrum) then stimulates the auditory region of the inner ear.

Weberian apparatus:

Cyprinids  The cyprinids are one of the largest families of the Ostariophysi (about 2,400 species) and the group includes the carp, goldfish and minnows.  The cyprinids lack a stomach and their jaws are toothless. Instead they depend on their pharyngeal teeth to chew food against a chewing plate formed from an extension of the skull.  The pharyngeal teeth are sufficiently strong that fish such as carp are able to consume hard shelled prey such as snails and mussels.

Carp  Colloquially carp refers to the largest species of cyprinids and these have a close historical association with humans having been farmed for food especially in Eastern Europe and Asia and as an ornamental fish for centuries.

Carp others/carp jpg

Koi carp Goldfish and koi carp are among the most well known of the ornamental carp

Catfish  About 1,800 species. Named catfish for the prominent barbels (as many as 4 pairs) that many species have, which resemble a cat’s whiskers and are used for food finding. how-to-catch-catfish/

Catfish  Freshwater fish found worldwide. Most are bottom-feeders and are negatively buoyant having a small swim-bladder and a heavy flattened head.  Catfish (like carp) have been widely caught and farmed for centuries. They can easily be raised in large ponds in warm climates and there is a large catfish aquaculture industry in the southern U.S.

Catfish  Many species are quite small reaching only 4” in length, but others can be enormous. The largest is the giant Mekong catfish that has been known to reach over 10’ long and a weight of 650lbs. This is the record for the world’s largest freshwater fish.

Catfish  Most catfish possess a strong hollow spine-like ray on their dorsal and pectoral fins. These can be locked in place as a defensive mechanism and can inflict severe wounds. Some species produce a toxic protein that can be delivered by these spines. In a few species the toxin is dangerous and in rare cases lethal to humans.

Piranha  Piranha belong to the family Characidae in the Ostariophysi. They are south American fish and occur in the large river basins of the Amazon, Orinoco and similar rivers. Estimates of the number of species range from species  They are known for their sharp teeth and have a fearsome reputation as carnivores.

Piranha  They are relatively small deep-bodied schooling fish 5-10” long and easily recognized by their dentition. They possess a single row of sharp triangular teeth in both the upper and lower jaws.  The piranhas (specifically one species the red- bellied piranha) reputation for ferocity appears to have been greatly exaggerated, but attacks on humans do occur especially in situations where in shallow water where fishing and gutting is taking place.

Piranha piranha.jpg Animal%20Articles/Piranha.html

Piranha clip  50HU 50HU 50HU

Superorder Protacanthopterygii  The superorder includes about 500 species of which the esocid [pike] and salmonid fishes are the most familiar.  The group originated about 150 mya and numerous fossils are known from the Cretaceous.  They are a temperate water group and most species are found in the northern hemisphere.

Superorder Protacanthopterygii  Many Protacanthopterygii (e.g. salmonids) possess an adipose fin, which is a soft fleshy fin found on the back behind the dorsal fin and just forward of the caudal fin.  Function of this fin is unclear, but trout that have had it removed have an 8% higher tailbeat frequency and it has been suggested that it may have a sensory function in detecting sound, touch and changes in pressure.

Adipose fin Coho salmon

Superorder Protacanthopterygii  The salmonids include salmon, trout, char and grayling and the group includes many commercially important species.  The smallest salmonids are only about 5” long, but some salmon can reach 6’ in length.  Many species of salmon are anadromous and spend their adult lives at sea, but all salmonids spawn in freshwater.

Coho Salmon Rainbow Trout: staticfiles/NGS/Shared/StaticFiles/ animals/images/primary/rainbow-trout.jpg

Superorder Protacanthopterygii  Trout are close relatives of salmon, but usually live their entire lives in freshwater.  Salmon and trout are important commercial and recreational species.  Salmon have been a major focus of the aquaculture industry.

Superorder Protacanthopterygii  The esocids are a small order (only 10 species ) which is closely related to the salmonids and among the most primitive of euteleosteans.  They include pike, muskellunge, pickerels and relatives.  These fish (which superficially resemble gars) are voracious, stealth-hunting predators and important freshwater game fish in North America and northern Eurasia.

Muskellunge Muskellunge.jpg

Pike  Pike have a long, powerful muscular body and an elongated snout filled with long pointed teeth on which it impales its prey.  They have deeply forked tails, and paired dorsal and anal fins set well back on the body. These appear to be adaptations for rapid straight line acceleration.  Pike typically lie in wait and suddenly rush from cover to capture their prey.

Northern Pike

Superorder Paracanthopterygii  Includes about 1,340 species of cod, toadfish and anglerfish.  An almost exclusively marine group that ranges in length from a few cm to about 2 meters.

Gadiformes  Cod and their relatives (including pollock, ling, hake, and haddock) totaling about 475 species are cold water marine fishes and the basis of some of the most historically important marine fisheries.  Cod are the largest of the gadoids and may weigh up to 90 kg. They are mostly bottom dwellers and occur on the continental shelves from shallow water to 200 fathoms.  Cod migrate over long distances and assemble in large numbers to spawn. A single female may produce millions of eggs, which drift in the plankton.

Atlantic Cod:

Anglerfishes  Anglerfishes are named for their method of foraging which involves using a lure to attract fish close to them.  The lure is a modified spine of the anterior dorsal fin and can be wiggled like a prey item.  In deep sea anglerfish the lure contains bioluminescent bacteria that help attract prey from a distance.  Some bottom-dwelling anglerfish depend on camouflage and these fish have arm-like pectoral fins that they use to move long the bottom.

Anglerfish Black devil Anglerfish deeplight/media/fig3b_600.jpg

Superorder Acanthopterygii  Includes two major groups: Atherinomorpha and Atherinomorpha and Perciformes. Perciformes.  Atherinomorpha: More than 1,600 species of silversides, killifishes, grunions, flying fish and relatives.  These are mostly small silvery fish that are surface feeders.  There are about 50 species of flying fish (mostly tropical) that are members of the Atherinomorpha and they use their enlarged pectoral fins to glide 50 to 400m (depending on updrafts from waves) to escape predators.

Silversides

Flying fish

Acanthopterygii  The second major group is the Perciformes: more than 7,000 species of perch and their relatives.  Range in size from 7mm to 5m long. A paraphyletic group there is no set of derived traits that groups them all together, but they usually have dorsal and anal fins with anterior spiny portions, whereas the posterior spines are usually soft rayed. The two portions may be partially or completely separated.  Snook, sea bass, sunfish, perch, darter, snapper, cichlids, barracuda, tuna, most coral reef fish.

European Perch

Snook Black Seabass images/Black%20Sea%20Bass2.jpg

Barracuda images/cc_barracuda_national_park_service.jpg

Infraclass Osteoglossomorpha  Osteoglossomorpha: [greek bony tongue]. About 220 species of tropical freshwater fish. Includes from the Amazon Osteoglossum or Arawana, and Arapaima among the largest purely freshwater fish (regularly 3m long, but up to 4.5 m).  Also includes the African elephant nose fish, which are bottom feeders and that use weak electric signals to communicate with each other

Arawana

Arapaima

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