Amphibians

1. Amphibians

2. Characteristics • Ectothermic, Tetrapod Vertebrates with a endoskeleton that are restricted to moist or aquatic environments • Smooth moist skin developed for protection, water and temperature regulation, and gas exchange

3. Amphibious Lifestyle • Living in two different media (water and land) allows these organisms to take advantage of characteristics that each environment has to offer while limiting the competition between the fully aquatic and herbivorous larval stage and the amphibious and carnivorous adult stage

4. Waters Advantage Water shows less fluctuation in temperature than land, and is thus a very stable environment. Likewise, its buoyancy help support the body or aquatic organisms. Lands Advantage Air on land holds 20% more oxygen than water, and thus land dwelling amphibians can be more active Habitat Advantages

5. Evolution • Amphibians diversified into two distinct lineages, the amniote lineage that gave rise to the reptiles, birds, and mammals, and the non-amniote lineage that gave rise to current amphibians • Ichthyostega

6. Classification • Order Gymnophiona • Order Caudata • Order Anura

7. Order Gymnophiona (Caecilians) • Caecilians are worm-like amphibians that appear segmented • They are confined to tropical regions of the world and are burrowing creatures that feed on soil invertebrates

8. Order Caudata (Salamanders) • Salamanders tend to have unspecialized paired limbs and a tail • Most salamanders live in moist forested habitats • They have internal fertilization and lay their eggs in moist or aquatic habitats

9. Order Anura (Frogs & Toads) • Frogs & Toads have specialized hind limbs and lack a tail as adults (anura = witout tail) • Most frogs & toads live in aquatic habitats, have external fertilization, and develop through metamorphosis from aquatic larval tadpoles into more terrestrial adults