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Higher Chordates: “Fishes”. Petromyzontida - Sarcopterygii. Subphyla Vertebrata. Subphyla: vertebrata. Key adaptations allowed them to be more efficient @ capturing food and avoiding being eaten Endoskeleton Vertebrae:bone or cartilage
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Higher Chordates: “Fishes” Petromyzontida - Sarcopterygii
Subphyla: vertebrata • Key adaptations allowed them to be more efficient @ capturing food and avoiding being eaten • Endoskeleton • Vertebrae:bone or cartilage • Took over role of notochord & encloses spinal cord in most verts. • Closed circulatory system • Single well developed heart • Skull with a brain • Anterior to the spinal cord • Extinct vertebrate: • Conodont (jawless w/ “cone teeth”)
Class: Petromyzontida • ~35 species • Lamprey • Agnatha: Jawless • More pronounced Cartilage Skull • Keratin Teeth (not bony) http://www.youtube.com/watch?v=3K0ZrWWpqio
Clade: Gnathostomes • ~470mya • Jaws “jaw mouth” • Hinged structure • Derived from skeletal supports of the gill slits • Teeth • Rip apart food • Lateral line system • Organs run along the side of the body • Detect vibrations in the water • Extinct: placoderms/acanthodians
Class Chondricthyes • ~750 species • “Cartilage Fish” (bone in teeth & scales) • Cartilaginous “backbone” may have derived from bony skeleton ancestor • Sharks, Skates, Rays, Ratfish & Chimeras
Chondricthyes characteristics • Premier Predators • Streamlined body (power, not grace) • Oil bladder (helps buoyancy, sinks if it doesn’t swim) • Acute Vision (but colorblind) • Detect electric fields—lateral line system • For shark fins • Dorsal for stability • Pectoral & Pelvic for lift • Caudal for propulsion
Chondricthyes characteristics • Gills • Gas exchange (O2) • Short digestive tract • Nostrils of sharks used for smelling only
Chondricthyes characteristics • Reproduction (variety) • Oviparous • lay eggs & hatch externally • Ovoviviparous • keep eggs in uterus until hatching • Egg membrane sometimes breaks during delivery • Viviparous • Placenta – true live birth
Clade Osteichthyes • “Bony fish” • Ossification of the skeleton (Bone) • w/ Calcium Phosphate • Draw H2O across gills • Operculum protective bony covering • Swim bladder (buoyancy) • Gases moving between swim bladder & blood • Sound like any organ that humans have??? • Lateral line system • Mostly oviparous • Fish (Actinopterygii, Actinistia, & Dipnoi) http://www.youtube.com/watch?v=zvrigHi3pS0 http://www.scienceisart.com/B_SwimBladder/SwimBladder.html
1 http://www.kscience.co.uk/animations/anim_3.htm
Class Actinopterygii • Ray finned fish • Fins supported by bony rays http://www.howjsay.com/index.php?word=actinopterygii&submit=Submit
Each fin on a fish is designed to perform a specific function: • Dorsal fin. Lends stability in swimming. • Ventral (pelvic) fin. Serves to provide stability in swimming. • Caudal fin. In most fish, the Caudal or tail fin is the main propelling fin. • Anal fin. Also lends stability in swimming. • Pectoral fins. Locomotion and side to side movement. • Adipose fin. Stability.
Actinistia (coelacanth) Dipnoi (lungfish) Surface to gulp air into lungs Class SarcopterygiiLineages Actinistia & Dipnoi • Rod shaped bones surrounded by thick layer of muscle in pectoral & pelvic fins…hence “Lobe finned fish”. http://www.ucmp.berkeley.edu/vertebrates/sarco/dipnoi.html
What’s the difference? • Lobe-finned • Ray-finned