Early tetrapod's and amphibians

• transition from water to land, air is less dense, land has higher temperature fluctuations and there is more oxygen available on land
• tetrapods are dependent on water for breathing, their skin helps them breathe, mucus glands, small lungs and are ectothermic
• Modern Amphibians are largely water dependent, reproduction happens in the water, larvae have gills and thin skin for cutaneous respiration.
• Mordern amphibians are ectothermic and very diverse in species
• Grandular skin- rich in mucus and poison glands
• aposematic coloration- warning coloration and mimicry
• thin skin and water dependency makes them highly succeptable to environmental change
• Order Gmynaphonia - Caecilians
• Order gymnoaphoria - elongate, limbless and burrowing, many vertebrae, no limbs and reduced eyes, eats worms and other small vertebrates
• Reproduction in gmynaphonia - internal fertilization, egg deposited in moist ground near water, larvae developed within egg
• Order urodela- salamanders
• Order urodela ost have aquatic larvae and terrestrial adults, both are carnivores
• Respiration in urodela - vascular skin, external gills, lungs, both or neither. Typically born with gills which are lost at metamorphosis
• Breeding behaviors of urodela - egg and larval stages require water, internal fertilization in most, spermatophores
• Paedomorphis in urodela - dont complete metamorphosis and retain gills and fin like tail
• Order Anura- frogs and toads
• Order anura must live near water, reproduction requires water and water permeable skin
• Order anura all have tailed larvae with tailess jumping adults
• Reproduction in anura- amplexus
• Anuran families - ranidae (large frog in North America), Hylidae (tree frog) Bufonidae (true toads)
• Aunurans can undergo winter hibernation by keeping glucose in their circulatory system
• Anurans can keep young larvae in mouth, or under skin