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What is fish with out an eye. FSH History • Earliest fish had no jaws and no paired fins-filtered feed • 1st fish bodies covered with bony plates • For 100 million years-fish were the only vertebrates Superclass Agnatha • Jawless vertebrates • Most primitive, living vertebrates • Ostracoderms (extinct); lamprey and hagfish • Lack paired appendages; cartilaginous skeleton; notochord throughout life; rasping mouth Superclass Gnathostomata, I • Placoderms (extinct): first with hinged jaws and paired appendages • Class: Chondrichthyes~ Sharks, skates, rays • Cartilaginous fishes; well developed jaws and paired fins; continual water flow over gills (gas exchange); lateral line system (water pressure changes) Rise of Sharks & Bony Fish • About 400 mya all the other fish disappeared and were replaced by sharks and bony fish. • The jaws improved-developed the hyomandibular arch from gills • More fins developed. • Continue Sharks became the top predators- skeletons of cartilage • Sharks first fish with bony teeth • Sharks use internal fertilization and pups born alive • Skates and ray develop around 200 mya Life cycles: Oviparous- eggs hatch outside mother’s body Ovoviviparous- retain fertilized eggs; nourished by egg yolk; young born live Viviparous- young develop within uterus; nourished by placenta Bony Fish • Evolved 400 mya • Developed heavy bony skeleton for protection and anchoring of muscles • Evolved in fresh water • Developed two types – Ray finned most fish perch- has swim bladder95% of all fish are teleosts (advanced ray finned fish) – Lobe finned evolved 390 mya-fin is more like limb than fin-EX :Coelacanth • Some lobed-finned fish walk on land Key Adaptations • 1. Gills for breathing • 2. Backbone • 3. Single looped circulation system- blood is pump from heart to gills to body back to heart • Nutritional requirements fish are unable to make all the amino acids needed so they must get these amino acids by eating them- (true for all vertebrates) Superclass Gnathostomata, II • Class: Osteichthyes • Ossified (bony) endoskeleton; scales operculum(gill covering); swim bladder (buoyancy) • Most numerous vertebrate • Ray-fined (fins supported by long, flexible rays): bass, trout, perch, tuna, herring • Lobe-finned (fins supported by body skeleton extensions): coelocanth • Lungfishes (gills and lungs): Australian lungfish (aestivation) Bony Fish adaptations • Swim bladder secrets and absorbs gases in order to make fish rise or sink in water-gas is CO2 • Lateral line system sensory organ located along the side of a fish (hearing) • Gill cover (operculum) hard plate covering the gills that pumps to push water over gills (so fish doesn’t have to swim to breath.) Homework • Draw a picture of a fish and label each findetermine what each fin does.