CLASS AMPHIBIA

Amphibia refers to "double life", or life in water and on land

Includes the salamanders, frogs, toads, and caecilians with approximately 3,900 spp.

Characterized by:

Amphibian reproduction variable Amphibians are Amphibians are represented by three subclasses Three primary orders of Amphibia within the Subclass Lissamphibia Order Caudata - Salamanders In southern US reproduction occurs primarily in the winter Sexual dimorphism limited - little differences between males and females 90% of all salamanders utilize spermatophores for internal fertilization

Egg and larval development may follow one of five general pathways

Reproductive strategies based on site of oviposition Family Cryptobranchidae - hellbenders Family Ambystomatidae - mole salamanders Family Amphiumidae - congo eels Family Plethodontidae - lungless salamanders Family Necturidae (Proteidae) - mudpuppies Family Salamandridae - newts Family Sirenidae - sirens Order Anura - frogs and toads Generalized reproductive pattern
males vocalize to attract females
amplexus (clasping of the female by the male for mating) brings the cloacas of the male and female together
external fertilization of eggs by sperm; both deposited in the water
tadpoles develop - length of development depends on the species
metamorphosis
adults predaceous - insectivorous/carnivorous

Two primary reproductive positions:
Axillary - male grasps the female just behind the forelimbs
Inguinal - male grasps the female around the waist just in front of the hind limbs
remain in position until eggs and sperm are released for fertilization

Family Ascaphidae - tailed frog

Family Pelobatidae - spadefoot toads Family Leptodactylidae - narrow-toed toads Family Bufonidae - true toads Family Hylidae - tree frogs Family Ranidae - true frogs Family Myrohylidae - narrow-mouthed toads Primary skeletal modifications in Anurans Order Apoda (Gymnophiona) - Caecilians Generalized amphibian integument