Infraclass Teleostei: “Teleosts”

1. 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.

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

5. 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).

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

7. 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.

8. http://people.biology.ufl.edu/sahilber/VertZooLab2007/Vert%20Zoo%20Images/Lab%202/Bowfin_skull_1.jpghttp://people.biology.ufl.edu/sahilber/VertZooLab2007/Vert%20Zoo%20Images/Lab%202/Bowfin_skull_1.jpg

9. 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.

10. 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.

11. 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.

12. http://141.213.176.11/site/accounts/information/Actinopterygii.htmlhttp://141.213.176.11/site/accounts/information/Actinopterygii.html

13. 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.

14. Lake Victoria cichlid http://www.petfishtalk.com/shows/090325.htm

15. 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.

16. 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.

17. 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.

18. 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.

19. 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 http://www.sciencedaily.com/r eleases/2007/09/070905134523.htm

20. Moray Eel Pharyngeal jaws http://en.wikipedia.org/wiki/File:Pharyngeal_jaws_of_moray_eels.svg

21. 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.

22. http://cichlid.umd.edu/cichlidlabs/kc/res/Cichlid.html

23. 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)

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

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

26. 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.

27. http://en.wikipedia.org/wiki/Leptocephalus Eel leptocephalus larvae http://www.australianmuseum.net.au/image/Eel-leptocephali/

28. Bonefish http://www.islaculebra.com/puerto-rico/fishing.html Tarpon http://www.wildernessaccess.com/images/ fishn/Tarpon-FISH-Justin- S-America-Venezuela-Los-Rogos.jpg

29. 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 80-280lbs. 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.

30. 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.)

31. 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.

32. http://www.richardcorfield.com/assets/images/silent_landscape/sargasso.jpghttp://www.richardcorfield.com/assets/images/silent_landscape/sargasso.jpg

33. American Eel http://www.peacefulparks.org/800x600/eels/ Anguilla-rostrata-2.jpg Eel larvae http://media-2.web.britannica.com/eb-media/17/54217-004-411C3896.gif

34. 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.

35. 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.

36. 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.

37. Herring http://pond.dnr.cornell.edu/nyfish/clupeidae/blueback_herring.jpg

38. Reef fish attacking a school of Pacific herring • http://www.youtube.com/watch?v=oBhK0_HjVe0

39. 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.

40. Superorder Ostariophysi • Members of the group possess two unique derived features: • alarm substances in the skin and • 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.

41. 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.

42. 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.

43. Weberian apparatus: http://www.aqua.org.il/pic/Articles/CatFish/12.JPG

44. 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.

45. 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.

46. Carp http://www.naturephoto-cz.com/photos/ others/carp-20524.jpg

47. Goldfish and koi carp are among the most well known of the ornamental carp Koi carp http://www.aqua-fish.net/show.php?h=koi

48. 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. http://fishingforbeginners.net/how-to-catch-catfish/

49. 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.

50. 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.