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Higher Chordates: Fishes & Amphibians

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

1 Higher Chordates: Fishes & Amphibians
Chapter 34

2 Phylum Chordata

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

4 Subphyla Vertebrata Endoskeleton Closed circulatory system
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 Lack paired fins, scales
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 H2O 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” Gas exchange
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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