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Amphibian Phylogeny Lungfish • First discovered 1830 • Lungs similar to land animals • Modified swim bladder • They are closest relative of tetrapods (4 legs) • • • • Tooth enamel Similar skull bone structure Pulmonary and systemic circuit of blood flow Four similar sized limbs Lungfish Coelacanth • http://www.pbs.org/wgbh/nova/nature/anatomycoelacanth.html • Type of lobed-finned fish Origins of Amphibians • Metamorphosis Apoda: Worm like Urodela: Newt/Salamander • Michigan Species • • • • • • • • • Blue-spotted Salamander Eastern Newt Eastern tiger salamander Four-toed salamander Marbled salamander Mudpuppy Red-backed salamander Small mouthed salamander Western lesser siren Examples of Michigan Urodela • Blue-spotted • Marbled Eastern Newt 4-toed Anura • Michigan Species • • • • • • • • • • • • Blanchard’s cricket frog Bullfrog Eastern American toad Fowler’s Toad Grey tree frog Green frog Mink frog N. leopard frog N. spring peeper Pickerel frog W. chorus frog Wood Frog Michigan species • Bullfrog • Wood greenfrog Spring peeper leopard Pickerel Salamanders • Tailed amphibian • American Hellbender • • Must live in moist areas • Secrete mucus • Maintain moisture • Balance salt levels • Protection Salamanders vs. Lizards: Skin Salamanders Similar to Ours Claws No Posture Body low to the ground Life Cycle Start as Larvae Lizards Covered in Scales Yes Body held higher above the ground Start as smaller adults Salamander Respiration • Types of Respiration: • External gills • Mudpuppy • Lungs • Single simple lung • Very inefficient • Skin (cutaneous respiration), all salamanders can do this • Why they must remain moist Environmental Issues • Salamanders, like all amphibians are one of the first organisms to be affected by environmental changes due to their soft-shelled eggs and respiring skin. • Aquatic eggs are jelly-like and can be affected by UV and chemicals in the water. • All salamanders can breathe through their skin so any chemicals that come in contact with them easily pass into their bodies. • Moisture is critical to all salamanders. • Deforestation leads to areas with less moisture, effectively destroying terrestrial salamander habitat Anura (Frog/Toad) • Live everywhere (except Antarctica) • Most species in tropics • Ectotherms • Evolved capabilities to live in all biomes • Desert, mountain, tropics, freshwater systems Toads • • • • Rough, dry skin Very terrestrial Use soil to maintain body moisture Need water source for larva stage (tadpole) Toads Frogs • Smaller body structure than toad • More angular than toad body • More reliant on water than toads • Moist skin • Secrete mucus • Similar to function in salamanders Anterior Anatomy • Key Features • Nicitating membrane • 3rd eyelid • Tympanic membrane • External eardrum • Eustachian Tubes • Balance pressure • Teeth • 2 vomerine teeth: • Maxillary teeth: hold prey Anterior Anatomy Skeletal System • Similar to mammalian skeleton • Functions as system of levers • Muscle attachment Digestive • Very similar to other vertebrates • Digestive Tract: What nutrients pass through • Mouth Esophogus Stomach Small Intestine (duodenum, ileum) Large Intestine/Colon Cloaca Vent • Accessory Organs: Provide enzymes • Liver/gall bladder • Gastric gland • Pancreas Excretory System • Use skin to excrete some waste (respiratory waste) • Cloaca collects digestive waste • Kidney major excretory organ • Urinary system Circulatory System • Pulmonary and systemic circulation • Pulmonary: Heart Lung Heart • Systemic: Heart Body Heart • Atrium(s) • Left: collects blood from lung, sends to the ventricle • Right: Collects blood from body, sends to ventricle • Ventricle • Pumps blood to both lungs and body Major Vessels • • • • Conus arteriosus: Heart systemic or pulmonary circ. Pulmonary vein: Lung Heart (LA) Pulmonary artery: Conus arteriosus lung Sinus Venosus: Body Heart Problems w/ 3 chambered Heart • Not as efficient as a 4 chambered (mammalian heart) • Oxygenated and deoxygenated blood mix • Lungs get some blood that is already oxygenated • Body gets some blood that is already deoxygenated Respiration • Use both lung and skin to exchange gases • Skin = pulmocutaneous circulation • 4 options for respiration • • • • • May use one or more Lungs (adult) Skin (adult) Mouth (adult) Gill (larva, some adults-mudpuppy) Nervous • Similar to that of a fish Reproductive • Do not have amniotic egg • No water barrier must keep moist • Most use external fertilization • Male fertilizes eggs as female lays them
