1. Fish and Amphibians

2. Phylum Chordata
The phylum Chordata includes fish, amphibians, reptiles, birds, mammals and a few invertebrate classes. They are placed in this phylum because they all have a notochord.

3. Invertebrate Chordates
The simplest chordates are the tunicates and the lancelets. They both have a notochord in their larval stage.
Lancelets Tunicate

4. Subphylum Vertebrata
The remainder of the organisms belong to the subphylum Vertebrata. They all have vertebrae surrounding their spinal chord, an endoskeleton, most have a hinged jaw.

5. Classification Kingdom Animalia Phylum Chordata Subphylum Vertebrata
Classes Agnatha
Chondrichthyes Osteichthyes
Amphibia

7. Agnatha: Jawless Fish Examples: sea lamprey, hagfish
Characteristics: Lack jaws, cartilage skeleton, no scales, unpaired fins, cold blooded (ectothermic).

9. Chondrichthyes: cartilage fish
Examples: sharks, skates, and rays
Characteristics: Cartilage skeleton, moveable jaws, paired fins, placoid scales, internal reproduction, cold blooded.

10. Shark Reproduction
Sharks are ovoviviparous. That means that they have internal reproduction, have eggs that hatch inside the mother and then the babies are born alive.

11. Identification of male sharks

13. Osteichthyes: bony fish
Examples: trout, salmon, lung fish, Ceolacanth
Characteristics: Bony skeleton, paired fins, moveable jaws, swim bladder, bony scales, indirect external reproduction, cold blooded and a lateral line system.

14. Classification of Bony Fish
Lung Fish – are fish that have a pouch branched off from the esophagus. It is a very primitive lung. This is not very efficient but they can survive during droughts by digging into the mud, breathing slowly until the rains come.

15. Lungfish in mud

16. Lobed Finned Fish One living species: Ceolacanth
The Ceolacanth has bones in its fins. These fish are common in the fossil record.

17. Ceolacanth

18. Ray Finned Fish
These bony fish have rays in their fins. Most fish belong to this class.

19. Reproduction
Fish reproduce by indirect external reproduction. The female prepares a nest, lays her eggs in the nest and then the male squirts sperm over the top of the egg pile. Not all of the eggs get fertilized.

21. Amphibians Examples: Frogs, salamanders, toads, newts…
Characteristics: Moist thin skin, lungs as an adults: gills as a larva, two chamber heart as larva: three as adult, Must lay eggs in water (no shell on eggs), toes with no claws, no scales, tympanic membrane, direct external fertilization and cold blooded (ectothermic).

23. Larva
The larva stage of an amphibian has a two chamber heart, fins, gills.

24. Classification of Amphibians
Frogs and Toads belong to the order Anura. They have large hind legs and no tail. They must go back to water to lay their eggs (except as few toads).

25. Urodela
Salamanders and Newts belong to the order Urodela. They have tails, long slender bodies and equal sized legs. Some like the mudpuppy keep gills their whole life.

28. Apoda
The order Apoda are the legless amphibians. They live in tropical regions and live in moist soil.

29. Reproduction
Amphibians reproduce by direct external reproduction. In a hold called amplexus, the male, on the back of the female, pushes the eggs out of the female and fertilizes each egg as it passes out of the female.

30. Metamorphosis
All amphibians go through some type of metamorphosis. This is the change from an egg, to a larva (tadpole) to an adult.

31. Pollution
Amphibians are very sensitive to pollution. Worldwide the number of amphibians is decreasing. Pollution kills them and can cause strange mutations. Radiation getting through the ozone layer causes damage to the embryos.

32. Other problems