Phylum Chordata

Chordate: animals that have a notochord in the embryonic form

Notochord: a flexible rod that extends the length of the body

4 Characteristics of Chordates 1. Dorsal nerve cord 2. Notochord 3. Pharyngeal gill slits 4. Tail

Subphylum Vertebrata: animals whose dorsal nerve cord is protected by a series of bone

4. Vertebrae that encloses/protects the nerve cord Characteristics 1. Endoskeleton 3. Hinged Jaw 2. Skull and Backbone 4. Vertebrae that encloses/protects the nerve cord

Fish: most primitive vertebrates

Ichthyology: study of fish -first jawed vertebrates -evolved during the Devonian Period (350 MYA) -fins/scaled/gills -two chambered heart with a closed circulatory system

Fish Heart Atrium: a chamber that holds blood before pumping it into the ventricle Ventricle: muscle chamber responsible for pumping blood throughout the body

Fish external anatomy

Fish Taxonomy Fish Class Agnatha (jawless) Class Osteichthyes (bony) Class Chondrichthyes (cartilagenous)

Class Agnatha: “no jaws” -circular mouth with teeth -freshwater parasites -elongated bodies Ex. Lamprey

Class Chondrichthyes: sharks and rays -cartilage skeletons -lack gill cover -detect electric fields from muscle contractions -swim to keep from sinking Ex. Nurse shark, sand skate

Class Osteichthyes: bony fish -ossified (boney) skeleton -operculum: protective gill cover -skin glands that secrete slimy covering Ex. Muskellunge, rainbow trout, chinook salmon, Carp, lake sturgeon,walleye, flathead catfish, longnose gar, smallmouth bass, whitehorse sucker, yellow perch, black crappie, white crappie

Class Amphibia: “double life” Introduction: -linked to water for reproduction -evolved in the Carboniferous period -ecosystem was all wetlands

Class Amphibia: “double life” Characteristics: -aquatic larval stage with gills (tadpoles) -four legs - tetrapods -herbivores as larva; carnivores as adults -respiration with lungs and through skin -external ear drums -three chambered heart

Specimens -grass frog (Rana pipiens) -bull frog -american toad -red-spotted newt -red eyed tree frog -African clawed frog -poison dart frogs

Class Reptilia First terrestrial quadriped Amniotic egg (oviparous reproduction) -body covered with scales -breath entirely with lungs - “3.5” chambered heart

Specimens King snake Ball python Reticulated python Water mocassin Snapping turtle Map turtle Leatherback sea turtle Eastern painted turtle Anole American alligator