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Download Phylum Chordata Subphylum Vertebrata Class Amphibia
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Phylum Chordata Subphylum Vertebrata Class Amphibia Amphibians Amphi – double; frogs, toads, caecilians, salamanders • Thin, moist skin • 4 legs • terrestrial, but closely tied to water Amphibians • both internal and external fertilization • eggs lack protective • membrane and shell – need water to prevent dessication. red eye tree frog eggs http://nationalzoo.si.edu/Animals/Reptile sAmphibians/Exhibit/Topics/zoo_breedi ng.cfm?inc=o Ectotherms • body temperature is dependent on environmental temperature • become dormant during times of year when it is too hot or too cold - estivate Metamorphosis Metamorphosis in frogs Herbivorous tadpoles hatch with internal gills • increase in mouth and tongue size • loss of gills / formation of lungs • growth of legs, resorption of tail • new visual pigment in eyes • hemoglobin protein in blood • insectivorous adult Metamorphosis in salamanders • young aquatic salamanders have gills and a tail fin • adults do not have gills or fins – breathe through skin or with lungs Metamorphosis in salamanders Some salamanders do not have larval stage, but hatch as small versions of adults Circulatory System • 3-chambered heart • one chamber gets oxygen rich blood from lungs • one chamber gets oxygen poor blood from body tissues • blood from both go to third chamber – blood goes to body tissues and skin Order Anura Frogs and Toads Frogs • smooth, moist skin • long legs Toads • bumpy, dry skin • short legs Both are tailless and insectivorous Order Anura Frogs and Toads • vocal cords capable of producing a wide range of sounds. • Vocal cords are sound-producing bands of tissue in the throat. Order Caudata Salamanders • long, slender body with a neck and tail. • smooth, moist skin • lack claws • a few cm to 1.5 m • carnivorous Order Apoda Caecilians • burrowing amphibians, have no limbs, and have a short, or no, tail. • primarily tropical animals with small eyes that often are blind. • eat earthworms and other invertebrates found in the soil. • have internal fertilization. Origins of Amphibians • Most likely, amphibians arose as their ability to breathe air through well-developed lungs evolved. • The success of inhabiting the land depended on adaptations that would provide support, protect membranes involved in respiration, and provide efficient circulation. Origins of Amphibians • Amphibians first appeared about 360 million years ago. • Amphibians probably evolved from an aquatic tetrapod around the middle of the Paleozoic Era. Challenges to life on land • Land life for amphibians held many dangers. • Unlike the temperature of water, which remains fairly constant, air temperatures can vary greatly. • In addition, without the support of water, the body was clumsy and heavy. Challenges to life on land • Able to breathe through their lungs, gills, or skin, amphibians became, for a time, the dominant vertebrates on land.
