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Higher Chordates: Fishes & Amphibians Chapter 34.

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Presentation on theme: "Higher Chordates: Fishes & Amphibians Chapter 34."— Presentation transcript:

1 Higher Chordates: Fishes & Amphibians Chapter 34

2 Phylum Chordata

3 Recall: Subphylum Urochordata –Tunicates Subphylum Cephalochordata –Lancelets Class Myxini –Hagfish –Least derived craniate lineage still surviving Chordates with a head

4 Subphyla Vertebrata Endoskeleton –Vertebrae: bone or cartilage Closed circulatory system –Single well developed heart Skull with a brain –Anterior to the spinal cord Extinct vertebrate: –Conodont

5 Class Agnatha Jawless fish –Ostracoderms extinct –Cyclostomes Lampreys, hagfish Lack paired fins, scales First organisms with a backbone Appeared 500 mya

6 Class Acanthodia Spiny fish Developed jaws with bony edges –Gnathostomes Internal skeletons of cartilage Extinct Appeared 430 mya

7 Class Placodermi Fish with massive heads Extinct Appeared 410 mya

8 Class Chondricthyes Cartilage fish (bone in teeth & scales) Sharks, skates, rays, ratfish & chimeras Appeared 400 mya

9 Chondricthyes characteristics Premier Predators –Streamlined body (power, not grace) –Oil bladder (buoyancy) –Acute vision (but colorblind) –Detect electric fields

10 Chondricthyes characteristics Reproduction (variety) –Oviparous lay eggs externally –Ovoviviparous keep eggs in uterus until hatching –Viviparous Placenta – live birth

11 Class Osteichthyes Ossification of the skeleton (Bone) Draw H 2 O across gills –Operculum bony covering Swim bladder (buoyancy) Mostly oviparous Appeared 400 mya 95% of today’s fishes

12 Subclass Actinopterygii Ray finned fish –Bony rays in fins for maneuvering, defense, and other functions

13 Subclass Sarcopterygii Lobe finned fish –Rod-shaped bones in fins surrounded with thickened layer of muscle –Swim or “walk” across substrate Actinista (coelacanth) Dipnoi (lungfish)

14 Evolution of tetrapods One of the most significant events in vertebrate history was when the fins of some lobe-finned organism evolved into the limbs and feet of tetrapods

15 Class Amphibia “Two lives” –aquatic larva develops into a terrestrial adult Gas exchange –Lungs and moist skin All amphibians must lay eggs in water

16 Order Urodela Salamanders –tails

17 Order Anura Frogs and toads –No tail

18 Order Apoda Caecilians –Legless –Wormlike –Burrowing

19 Amphibian Metamorphosis

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