Evolution of Fish :Chondrichthyes Evolution of Fish Armin Eskandari


Gnathostomata :Gnathostomata Gnathostomata(Jawed Vertebrates) Placoderms Chndrichthyes (Cartilaginus fishes) Osteichthyes (Bony fishes)


Anatomical Charteristics(Chondrichthyes) :Anatomical Charteristics(Chondrichthyes) Cartilaginous skeleton Not Fused Theet to Jaw Theets Replaced in rows Unsegmented and eppidermal fin rays(ceratotrichia) Single,Ventral Nosetrilson (each side of head) Spiral valve intestinal Pelvic Fin Males:Klasper (internal Fertilization) heterocercal caudal fin


Fossil form (Chondrichthyes) :Fossil form (Chondrichthyes) Sharkes From Upper Deveoian :No Clasper Fossil record of silurian common by Devonian Samples Contrast with Bony fishes(Their early Evolution in Freshwater)


Chondrichthyes Ecology :Chondrichthyes Ecology Found in Marine (a few in tropical rivers) Carnivores, with different prey: Other fish (most sharks) Benthic invertebrates (dogfish, skates, rays) Planktivores - Zooplankton (basking - filter-feeders) Piscivores : (Piscivore : a Carnivorous animal which lives on eating fish).   small scale -  Whale shark(Rhinodon)   large scale - great white shark (Carcharodon)


Chondrichthyes Reproduction :Chondrichthyes Reproduction Oviparous (skate) Eggs develop in cases outside the mother Viviparous (a few) Embryos nourished from uterine lining Ovoviviparous (dogfish) Embryos nourished by yolk in uterus oviparous - egg hatches outside, (Artemia ) ovoviviparous - egg hatches inside, young "born alive“ (,Artemia) viviparous - live bearing


Diversity of Chondrichthyes :Diversity of Chondrichthyes Squaliformes - typical modern sharks (350 spp.) fusiform, pelagic, marine predators, sometimes benthic or sedentary, rarely freshwater     5-7 gill openings         neutral buoyancy without swimbladder     genital claspers in males (sexual dimorphism)


Sensory System :Sensory System - directional olfaction in hammerhead shark (Sphyrna) - vibration : lateral line systems - vision - tapetum lucidum works well in reduced light &colour - electroreception (The eye has a layer of reflecting plates called tapetum lucidum behind the retina) - Ampullae of Lorenzini  detect weak electrical fields -  fluid fills sacs on rostrum (snout)


Class Chondrichthyes :Class Chondrichthyes sC: Elasmobranchii    O: Squaliformes (Modern Sharks)   O: Rajiformes (Skates&Rays )     sC: Holocephali    O: Chimaeriformes (Ratfish,Chimaeras)


sC: Elasmobranchii :sC: Elasmobranchii Predators, appeared in middle Devonian,No good fossil (teeth), Ray appeared inJurassic, 5-7 gill openings, a spiracle(lose in some forms), placoid scalese,Upper jaw not fused to cranium,lower jaw has amphistylic and hyostylic attach,teth replace numerous and rapidly,


Re: sC: Elasmobranchii :Re: sC: Elasmobranchii Devonian Cladoselachiaus Shark is ancestral, no clasper, a longhate Skull,Amphstylic Jaw, No Anal Fin, Paired Fin, sharp teeth, Pradotor (Carboniferous Molluscs and Cephalopods Was flat), Pavment like teeth,


Re: sC: Elasmobranchii :in Devonian Cladoselachians diversify in salt water,The Xenacanth Sharks(Xenacathii)were common in freshwater.(like lobe finned fishes during Triassic.P) İn Permian cladoselachians replaced by: 1-Hybodont Sharks (infraclass: Neoselachii) 2-modern sharks 3- Rays Re: sC: Elasmobranchii Hybodont feeding on large,active invertebrates( such as squid), with sharp teeth infront of jaw(biting) and blunt teeth behind them(Crushing). İn Jurassic P. Hybodonts rise to modern Elasmobranchs(infraclass: Neoselachii). Elasmobranchs (infraclass: Neoselachii) characterized by: 1-Diferent form of pelvic fin Cartileges, 2-Teeth and placoid Scales, 3-Calcified Vertebrae.


sC: Holocephali :sC: Holocephali Chimaeras:bootom-Dwelling,feeding on invertebrates,in upper Devonian and Carboniferous,a single gill cover over 4 gill opening,No Spiracle,Upper jaw fused to cranium,Male have a claspert,Modern type Chimaeras first appeared in the jurassic P.


Slide 15:Holocephalii(chimeridae, ratfishes) 30 Species,bottom dwelling,present since 400My


ACANTHODII :ACANTHODII Climatius, an acanthodian about three


Re: ACANTHODII :The fossil remains of the first jawed fish are found in Lower Silurian rocks and belong to the acanthodians, characterized by: large spines( Spiny Shark),scales covering much of the body Oldest jawed vertebrates(440 milyon),fossils most some were in 20cm,larg and flexible eyes,Boyy coverd by aerodynamic body(armor), spin front of all fins,Finflod yheory:origin of paired fins(and limb): predecessors of fin were lateral fold = used to swimming and ... Plankton feeding in freshwater and marine in permian.p , after extinct of placoderms, İn last 30 years offshoot of Chondrichthyes. Re: ACANTHODII


Osteichthyes(Bony fishes) or teleostomi :Osteichthyes(Bony fishes) or teleostomi Sarcopterygii(Lobe-finned fishes) Acthinopteriygii(Ray-finned fishes) Coelacanthiformes( (Coelacanths) Dipnoi(Lung fishes) Osteichthyes(Bony fishes) Evolved in fresh water


Re: OSTEİCHTHYES sarcopterygıı :Re: OSTEİCHTHYES sarcopterygıı Sarcopterygıı(lobe-finned fishes): 1-Actinistia ,2-Dipnomorpha, 3-ostenopterygii Present swimbladder and developed t to Lung and hydroststic organ,evolved in fresh water in tropical regions, first osification and contain a layer of dermal bone overlaid(Asipenseriformes),


Slide 20:Re: sarcopterygıı


Re: sarcopterygıı Actinistia :Re: sarcopterygıı Actinistia


Re: sarcopterygıı Dipnomorpha :Re: sarcopterygıı Dipnomorpha


Re: sarcopterygıı Osteolepimorpha :Extincted, rise to tetrapoda,air-breathin pradator in tropical invaironments, Re: sarcopterygıı Osteolepimorpha


Slide 24:Actinopteygii(Ray finned fishes) Actinopteygii Neopterygii(other modern bony fishes) Chondrostei(Sturgeons and paddlefishes)


Slide 25:Re: ACTINOPTERYGİİ Condrostei


Re: ACTINOPTERYGİİ Condrostei :Re: ACTINOPTERYGİİ Condrostei


Re: ACTINOPTERYGİİ Condrostei :Re: ACTINOPTERYGİİ Condrostei


Re: ACTINOPTERYGİİ Condrostei :Re: ACTINOPTERYGİİ Condrostei


Re: ACTINOPTERYGİİ Condrostei :Re: ACTINOPTERYGİİ Condrostei


Re: ACTINOPTERYGİİ Condrostei :Re: ACTINOPTERYGİİ Condrostei


Re: ACTINOPTERYGİİ Condrostei :Re: ACTINOPTERYGİİ Condrostei


Re: ACTINOPTERYGİİ Condrostei :Re: ACTINOPTERYGİİ Condrostei


Re: ACTINOPTERYGİİ Condrostei :Re: ACTINOPTERYGİİ Condrostei


Slide 36:Re: ACTINOPTERYGİİ Neopterygii


Slide 37:Neopterygii (modern Bony fishes)


Neopterygii (modern Bony fishes) :Neopterygii (modern Bony fishes) Male Male


Neopterygii (modern Bony fishes) :Neopterygii (modern Bony fishes)


Evolutiomary Trends within The teleosts :Evolutiomary Trends within The teleosts


References: :References: http://www.mun.ca/biology/scarr/Chondrichthyes.htm http://io.uwinnipeg.ca/~simmons/16cm05/1116/chordate.htm www.fish.gov.au/fishnames/fishnames.php?pid=308 http://www.atlanticanglers.com/fish/ http://www.diving.no/index.php?option=com_content&task=view&id=34&Itemid=1 http://www.palaeos.com/Vertebrates/Units/070Chondrichthyes/070.950.html http://www.elp.manchester.ac.uk/pub_projects/2003/MNZO0MLK/lectur9.jpg http://www.sju.edu/research/bear_gulch/pages_fish_other/fish_parts_head.php http://www.learningtreasures.com/suite101/science/bony_fish.jpg http://www.marinebiodiversity.ca/shark/english/reproduction.htm http://www.discoverfossils.com/Geology/images/GeologicalPeriodLg.jpg http://www.cites.org/gallery/species/fish/great_white_shark.html http://www.thejump.net/id/more-fish/Ratfish-Chimaera-monstrosa.jpg