WILD 3580 1st Edition Lecture 14 Outline of Last Lecture I Functions of Smell II Electroreception III Magnetic Reception IV Exam review Outline of Current Lecture I Amphibian Evolution II Classification III Ecological Roles IV Skin Current Lecture I II Amphibian Evolution Rhipidistians fishes subclass Osteolepimorphi o Gave rise to amphibians terrestrial tetrapods Choanae internal nares connection between nasal cavity and respiratory system Maximum diversity during Carboniferous period Age of Amphibians in the Paleozoic era Classification 3 Orders Anura frogs and toads most diverse 4700 species Caudata salamanders 475 species and Gymnophiona Caecilians 170 species 1 Ectothermic variable temperature body temperature depended on environment a Energetically inexpensive 2 Small body size a 90 of frogs and salamander species weigh less than 20 grams i Minimizing overlap with other larger species between niches ii Tendency to lose energy ectothermic iii Smaller endothermic species have higher metabolic rates b Largest amphibian is the giant salamander 5 feet 3 Double life a Many amphibians have a larval stage and an adult stage i Larvae Metamorphosis Adult 4 Skin lacks scales and is permeable to water These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute III IV a Some breath through their skins and absorb water through the skin b However water can also be lost in drier environments 5 Toes lack claws or nails Ecological Roles Mostly active at night no sun higher humidity maintain water near water o Hard to observe during the day time o Easily to underestimate their importance 1 Invertebrate Predator a Primary vertebrate predator in some areas b Adult amphibians are carnivorous feed on invertebrates c Efficient at converting food to body mass don t have to maintain metabolism can convert food energy into growth and development 2 Plant Predators a Larval amphibians feed on plants 3 Energy transfer a Between invertebrates and plants in higher tropic levels b Amphibians are the link between lower trophic levels to higher levels Skin Water permeable Functions o Barrier between external and internal environments protection from pathogens and abrasions o Respiration o Absorption and release of water o Secretions to keep the skin moist o Protection through toxic secretions o Coloration concealment or warning Structure o Epidermis outer layer is divided into 3 sublayers Stratum corneum outer most layer Dead cells that shed that are filled with keratin o Keratin a dense fibrous structural protein Alpha keratin makes up softer structures hair skin nails ect amphibians only have this Beta keratin make up harder structures shells beaks scales ect Relatively thin layer compared to other vertebrates Ecdysis periodic shedding of skin o Amphibians eat the skin recycle nutrients o How often they shed depends on many factors Stratum granulosum middle layer where cells go to die Living cells die and are filled with keratin Keratin replaces the cytoplasm of the cells Stratum germinativum basal bottom innermost layer Cells that undergo mitosis
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