Amphibians (Frogs and Salamanders)

Amphibians

Overview of Amphibians

• Amphi = "both", Bios = "life"
• Have a biphasic lifestyle
• Larval stage
• Tadpole: Frogs
• Larvae: Salamanders
• Fully aquatic
• Lacks legs
• Metamorphosis
• Larvae develop legs, lungs, eardrums, digestive track
• Many have evolved to be direct developers
• Lost the aquatic larval stage
• Fertilization is mostly external
• Some females lay many eggs with little parental care
• Others lay few eggs with great parental care
• Complex social behaviors
• Vocalizations
• Territoriality
• Amphibians are declining rapidly
• Fungal infections (Chytrid)
• Climate change
• Habitat destruction

Salamanders

• Urodeles
• ~550 species
• Some fully aquatic
• Some Biphasic life style
• Aquatic youth
• Terrestrial adults
• Paedomorphism: adults retain larval features even though sexually mature
• Walk on land with side to side movement of the body
• Similar to early tetrapod

Frogs

• Anurans
• ~5,420 species
• Includes Toads: frogs with leathery skin
• Adapted to drier conditions on land
• Better terrestrial locomotion
• Powerful hind limbs to jump
• Captures prey with sticky tongue
• Defensive toxins and warning colors to deter predators Example: Poison Dart Frogs

Caecillians

• Apodans
• ~170 species
• Legless
• Blind
• Typically in tropical climates