Transcript Vertebrates
Vertebrates Jawless fishes to Mammals Gills to Lungs Fish – one way circulation Amphibians – circulation loop Reptiles – partial septum - little mixing of blood Mammals and Birds – completely divided Fish Classes • Agnatha – Jawless fish, evolved about 540 MYA. Ex. Lamprey • Chondrichthyes – cartilaginous fishes. Ex. Sharks and rays • Osteichthyes – bony fish • Gills for respiration Agantha - Lamprey Jaw evolution Sharks Fast, powerful predators, Lateral line system – sensory organs running down the side of the body for detecting vibrations in the water Chondricthyes Bony Fish Hard skeleton with scales Protective operculum over the gills Swim bladder for buoyancy Ray finned fish – most bony fish like the tuna, bass, perch Lobed finned fish – ancestor to the amphibians Osteicthyes Perch anatomy Lobed finned fish Fish circulation Fish Circulation Fish One way Gills – body – heart http://www.hhmi.org/bioint eractive/circulatorium/fra mes.html Diagram Amphibians Living a double life – part water/part land Gas exchange through diffusion Complete metamorphosis Partially divided heart Ex. Salamander, frogs Amphibians Amphibian circulation Amphibian Circulation Loop Septum separates atria into right and left halves Ventricle pumps blood from the heart Deoxygenated blood enters The right atrium then to lungs http://www.hhmi.org/biointer active/circulatorium/frame s.html Diagram Reptiles Watertight skin and eggs Internal fertilization – no water needed Ectothermic Scales made of keratin Lungs Dinosaurs were numerous during the Mesozoic era By about 65 MYA, the dinosaurs were gone, with only the birds left. Turtles, crocodiles, lizards and snakes Reptile Heart Reptile Circulation Septum extends into the ventricle Blood going to the body is more oxygenated than amphibians Ectothermic – cannot maintain body temp. through metabolism. Must get heat from external source Reptiles Archaeopteryx Birds Class Aves Evolved during the mesozoic era Honeycombed bones for lighter weight Wings for flight, feathers made of keratin Endothermic – warmed by own metabolism No teeth, grind food with gizzard Birds Mammals Became diverse after the downfall of the dinosaurs Hair and mammary glands Endotermic Monotremes – duck-billed platypus and echidna, egg-laying mammals Marsupials – pouched mammals Eutherians – placental mammals Mammal Heart Bird and Mammal Circulation 4 chambered heart No mixing of blood Birds have multiple airs sacs for the most oxygen available to the lungs. Mammals have less oxygen per unit blood Capillary beds of lungs where gas exchange occurs Pulmonary Circuit Pulmonary arteries Pulmonary veins Aorta and branches Venae cavae Left atrium Left ventricle Right atrium Heart Right ventricle Systemic Circuit KEY: Oxygen-rich, CO2-poor blood Oxygen-poor, CO2-rich blood Capillary beds of all body tissues where gas exchange occurs Figure 11.4 Echidna Marsupials and Eutherian Phylogenic Tree Cladograms