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/
“The skin of amphibians is water permeable, well supplied with glands, and often colorful, with the colors and patterns of many salamanders and anurans rivaling those of brightly colored birds. It performs many functions. It protects against abrasion and pathogens, serves as a respiratory membrane, perhaps marginally so in caecilians, absorbs and releases water, provides some dry-land species during droughts with a water-loss-resistant cocoon, and through color change (in some species) a...
Pianka, E. and Hodges, W. 1995. Horned Lizards. University of Texas. Web. Accessed at http://uts.cc.utexas.edu/~varanus/phryno.html
Campbell, N. A., Reece, J. B., & Mitchell, L. G. Biology: Fifth Edition. Addison Wesley
Nicholson KE, Harmon LJ, Losos JB. Evolution of Anolis Lizard Dewlap Diversity. PLOS ONE. 2007
Shubin, N.H., & Marshall, C.R. 2000. Fossils, genes and the origin of novelty. Paleobiology, 26(4): 324-340.
Audesirk, Teresa, Gerald Audesirk, and Bruce E. Byers. Biology: Life on Earth with Physiology. Upper Saddle River, NJ: Pearson Education, 2011. 268-69. Print.
All references and resources are taken from the Public Library of Science, Biology March 2004 issue and from Science March 16, 2004
Miller, K. R., & Levine, J. S. (2010). Miller & Levine biology. Boston, Mass: Pearson
Cain, M. L., Urry, L. A., & Reece, J. B. (2010). Campbell Biology. Benjamin Cummings.
Smith, Hobart M. and Zim, Herbet S. Reptiles and Amphibians. New York: Western Publishing Company, 1987. Print.
Zacherl, Danielle. “Biology 171 Evolution and Biodiversity.” National Association of Research in Science Teaching 2007 Annual Meeting, New Orleans LA. (2007):n. page. Print.
Frogs live on every continent except Antarctica, but tropical regions have the largest amount. Like all amphibians, frogs spend half their lives near water because they must return to the water to lay their eggs. Frogs live underwater mostly when the are growing up to be an adult frog and when they are laying their eggs. When they hatch under water they are tadpoles and the breath with gills and swim using a tail. As they mature they loose their tail and they develop to be able to breathe air. During an extensive period of heat, a drought, frogs can enter a period of damancy similar to hibernation called starvation. Most of the frogs live in tropical and semitropical regions, most species of frogs breed in the spring or in early summer. Although the different species my vary in size and color, mostly all frogs have basic body structure. They have large hind legs, short front legs and flat head and body with no neck.
Amphibians are animals that are adapted to live on the land and in water habitats (Kolesova, et el, 2007). Young amphibians spend their early life in water breathing through their gills; as they grow they tend to lose their gills and develop lungs which allow them to be adapted to life on land as they will be breathing air (Kolesova, et el, 2007). There are a number of amphibians such as salamanders that do not do not have an aquatic stage in their life, they are completely terrestrial (Kolesova, et el, 2007). Some amphibians do not...
The above information was taken from Biology, Neil Campbell, et. al., New York: Addison Wesley, 1999, p.316.