Anuran Life Cycle

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Class amphibia, order anura contains all of the world’s frogs and toads. These creatures are defined by their large eyes, moist skin, relatively large hind legs and their lack of tails. Amphibians diverged from their closest primeval relatives, lobe-finned fish, in the Devonian era as the first tetrapods to set foot on land1. Examining the morphology of these animals can elucidate much of what made amphibians excellent candidates for land colonization. They had digits that allowed them to walk (albeit clumsily) on land, lungs that allowed them to breathe the air above them, and the beginnings of a neck that would allow them to snap at moving prey. Over time the clade diversified and Vieraella herbstii, the earliest known ‘true frog’ which lacked a tail, appeared in the Late Jurassic period2. The appearance of V. herbstii marked the beginning of the order Anura. Like all amphibians, Anurans lack the ability to produce amniotic eggs. Because they are unable to lay their eggs on land, nearly all organisms in this class spend their lives near a source of freshwater. The frogs need freshwater to lay eggs and pass on their genes but without a ready source nearby, any frog lineage will dry out. Another limitation faced by all amphibians, not excluding frogs, is the fact that their skin is vital for their respiration. They take in O2 and release Co2 through their porous covering and to do so, they need to stay moist3. Desiccation is a very real threat to all of amphibia which is why they are largely found in tropical environments and other areas of high humidity and precipitation. Frogs are all carnivores that feast on mostly arthropods like insects and spiders but some of the larger breeds can prey on small mammals and birds. Their s... ... middle of paper ... ...//sci.waikato.ac.nz. The University of Waikato, n.d. Web. 31 Mar. 2014. . [2] Evans, SUSAN E., ANDREW R. Milner, and F. R. A. N. C. E. S. Mussett. "A discoglossid frog from the Middle Jurassic of England." Palaeontology 33.2 (1990): 299-311. [3] Reece, Jane B., and Neil A. Campbell. Campbell Biology / Jane B. Reece ... Boston: Benjamin Cummings, 2011. Print. [4] Levine, R. P. "Contribution of Eye Retraction to Swallowing Performance in the Northern Leopard Frog, Rana Pipiens."Journal of Experimental Biology207.8 (2004): 1361-368. Print. [5] Fryer, Benjamin. "Rana Pipiens." AmphibiaWeb.com. Amphibiaweb, 4 June 2004. Web. 03 Apr. 2014. [6]Gilbert SF. Developmental Biology. 6th edition. Sunderland (MA): Sinauer Associates; 2000. The Frog Life Cycle. Available from: http://www.ncbi.nlm.nih.gov/books/NBK10035/

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