Biodiversity

Thursday, May 11, 2006

ADAPTATION REQUIRED TO MAKE TRANSITION FROM AQUATIC TO TERRESTRIAL LIFE USING AMPHIBIANS.

Amphibians are cold blooded vertebrate that spend some time on land but must breed and develop into water. Frogs, salamanders and toods are examples of amphibians. Amphibians are animals who lay their eggs in water and spend at least part of life on land. Amphibians begin their lives under water and breathe through gills. Adults live on land and breathe through lungs. Amphibians do not have muscles to help them to inflate and deflate their lungs. They depend on oxygen through their thin, wet skin.


Amphibians keep their bodies moist inorder to prevent the loss of water through their skin. They avoid dry by ling near the river and they must return back to water to reproduce. Amphibians such as bullfrogs and some salamanders spend most of their life in water. Toads and salamanders are independence from water and they are forced to return to water to reproduce. Tadpoles have gills which is used to breathe in water. Amphibians lives on land has a lung to breathe. Most of terrestrial amphibians they feed on insects including mosquitoes and black flies, and on aquatic they feed on plants or fish. Amphibians on land they jump and on aquatic they used to swim. For examples frogs, on aquatic they walk on swim and in land they jump.

Some of the amphibians live their whole life in water, while others live on land and return to water only to mate and lay their eggs. Some amphibians have smooth skin and live in water. E.g frogs. Some amphibians have warty skins and live on land. E.g Toads, they adapted to dry condition it breed intemporary pools after. Most reptiles are not dependent upon body water for reproduction. They can live in desert. Some reptiles such as snakes and few lizards have gone back to living in water but breath air through their lungs and emerge from water to lay their eggs on lands.


Crocodiles, gavials and caimans are aquatic but come out of the water to relax and build nests for their eggs. Crocodile and alligators breathe with lungs but they spend much time in water. Turtles are live on streamlined for swimming. They have feet which makes them coming onto land to lay eggs. Snappers and softshells come out from water to walk easy. Painted turtles and red-eared sliders come out inorder to busk in the sun. land turtles such as box turtles and wood turtles spend most of life on land but it like to soak in water occasionally.


The limitations to a terrestrial life of amphibians exhibit are: habitat loss, road construction, livestock activity: these livestock has resulted in the following disturbances: grazing and trampling have ruduced vegetation cover and create drier soil condition, water diversion, "unnatural flow regimes, introduce non-native fishes and bullfrogs and activities which increase sediments such as road construction, logging and intensive cattle grazing within frog habitat
Clearcutting, disturbance related to roads trails and deseases are the most important limiting factors of terrestriallife"(1). Deseases mass mortality of amphibians are caused by different deseases found on land. Climate condition have a major influence, such as drought which cause the death of amphibians.

“Terrestrial egg masses are more diffusion limited, because gravity and surface tension collapse them, preventing convection between the eggs, and restricting the source for oxygen diffusion. Terrestrial embryos are often larger than their aquatic counterparts and have higher demands for oxygen. Terrestrial conditions have selected for adaptations that reduce respiratory competition between embryos, for example, separating of embryos by large volumes of jelly or reducing the number of eggs in a clutch. The size of foam nests is unlimited, because oxygen for each embryo is supplied directly from the foam”(2).
References


1. Living Things Amphibians. [Online].Available from: http://www.greenscreen.org/newsletter/articles/Amphibians.html%20[2006, May 11]

2. Jennings.1996.Amphibians of the Big Chico Creek.[Online]. Available from: http://www.csuchico.edu/bei/BCCER/Biota/amphibians.htm%20[2006,May 11:20]

3. Wikipedia Contributors, Amphibians [Internet]. Wikipedia, The free encyclopedia, 2006 may 09, UTC [Cited 2006 may 11]. Available From:http://en.wikipedia.org/wiki/Amphibian

Linette Netshiheni
CSIR
Pretoria
0001
Cell: 0820446442
Tell: 012 841 2133
Fax: 012 842 3676
tnetshiheni@csir.co.za
Weblog: http://tnetshiheni-linette.blogspot.com/

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