Xenopus Laevisas a Model OrganismPhylogenetic analysis of data from DNA sequences and morphology indicate thatXenopusis monophyletic and thatSiluranais its sister group. The most basal lineages of Pipidae diverged prior to the breakup of Gondwana. The bizarre morphology ofXenopusis in part due to changes in the mode of metamorphosis. Speciation inXenopusis unique among Anura in being associated with various levels of polyploidy owing to allopolyploidy. Several kinds of molecular studies indicate substantial divergence between Xenopus and Silurana. Taxonomic name: Xenopus laevis (Daudin 1802)The species is Common names: African clawed frog (English)Organism type: amphibianTaxonomy:

Phylum: ChordataClass: AmphibiaOrder: AnuraFamily: PipidaeLife cycle: from aquatic larval stage to aquatic adult stage.Larvae: Aquatic, gilled tadpolesAdults:Reach sexual maturity 6-10 months following metamorphosisReproductionReproduction is successful in acidic and alkaline waters (pH 5-9) and may occur year round.Male attracts attention through vocalization.Females respond with acceptance or rejection.Mating occurs in water; males hold females in pelvic amphiplexus Females release eggs singlyFertilization is external; eggs adhere to vegetationFemales produce up to 27,000 eggs per clutch, and may produce multiple clutches under favorable conditions.

General Biology:Morphology Smooth skin Body flat, head small Webbed, clawed hind feet No tongue No teeth No external tympanic membrane (eardrum) Achieves 5" snout-to-vent lengthBehavior Aquatic as adults (air breathing) and larvae (gilled) Adults can move overland between water bodies Adept swimmer; moves awkwardly on land Adults are predatory; tadpoles are mid-water suspension feeders of zooplanktonDistinguishing Characteristics: Clawed hind limb toes distinguish the African clawed frog from all North American frogs and toads. Larvae appear transparent and have long barbels (making the tadpoles superficially resemble catfishes), distinguishing them from all other North American frog and toad tadpoles. Habitat Characteristics:

Wide variety of permanent and temporary freshwater habitats: marshes, streams, rivers, ditches, canals, lakes, reservoirs, and ponds. Most commonly found in stagnant or still waters of ponds or sluggish streams, but may also inhabit fast-flowing water. Highly salt-tolerant: can survive brackish waters consisting of up to 40 percent seawater. Aestivate for up to eight months during dry periods.Temperature Adults tolerate temperature ranges of 0-35 oC and tadpoles can survive temperature ranges of 10-30 oC. Populations persist under winter ice in some states.DIET African clawed frogs feed on aquatic insects, fish, amphibians (including cannibalism of their own larvae), and birds, and will scavenge on decaying debris. Cannibalism may play a major role in regulating population size. Adults can take terrestrial prey; tadpoles filter feed, primarily on zooplankton