Chordates Dr. Margaret Diamond The Animal Kingdom Chordates Dr. Margaret Diamond

Chordates Subphyla Urochordata – tunicates (invertebrate) Cephalochordata – lancelets (invertebrate) Vertebrata – jawless fish, cartilagenous fish, bony fish, amphibians, reptiles, birds, mammals

Chordate characteristics At some stage all have: Notochord Provides support Dorsal hollow nerve cord Spinal cord Fluid filled Pharyngeal gill slits or pouches Develop into gills or other body parts Post-anal tail

Chordate characteristics

Invertebrate Chordates Urochordata – tunicates Cephalochordata – lancelets Have all chordate characteristics BUT no vertebrae

Vertebrate Classes

Agnatha – Jawless Fish Lampreys and hagfish Have been around for 500 my Eel-like Smooth, slimy skin Round, jawless mouth Cartilagenous skeleton – no backbone May be parasitic Ectotherm (cold-blooded)

Cartilagenous Fish Chondrichthyes Sharks, rays and skates Skeleton of cartilage Lateral line system Senses changes in water pressure Excellent sight and smell Placoid (tooth-like) scales with denticles Oil in liver helps them to float – sink if stop swimming Gills – some must swim to breathe Ectotherm

Bony Fish Osteichthyes Tuna, goldfish, Nemo, etc. – 95% of all fish Bony skeleton Bony scales Swim bladder for buoyancy; can float in one place without swimming Ectotherm

Amphibia Frogs, salamanders, newts First vertebrates on land Legs Lungs Eggs fertilized and laid in water Larva = tadpole; develops in water Skin is thin, smooth, moist Can breathe through skin Ectotherm

Reptilia Lizards, snakes, turtles, dinosaurs, crocodiles First vertebrates to live completely on land – adaptations Thick, dry skin Amniote egg with leathery shell; laid on land Internal egg fertilization Stronger legs Ectotherm

Birds Aves Amniote egg with hard shell Internal fertilization Endotherm = warm-blooded Feathers Light-weight bones No teeth – crop and gizzard Crop stores food Gizzard has stones to grind food Air sacs – increase oxygen intake Legs and feet covered with thick, dry scales Endotherms (warm-blooded)

Mammalia Mammals Endotherms Internal fertilization Most give birth to live young (not eggs) Mammary glands (nurse young) Hair Teeth Lungs with diaphragm (helps with breathing – pulls air in and pushes it out) Larger brain