Phylum Chordata Chordate animals that have a notochord

Phylum Chordata

Chordate: animals that have a notochord in the embryonic form

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

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

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

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 1. Atrium: a chamber that holds blood before pumping it into the ventricle 2. Ventricle: muscle chamber responsible for pumping blood throughout the body

Fish external anatomy

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

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. Box fish, walleye, largemouth bass, porcupine puffer, piranha, black molly, catfish

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