Wednesday, May 10, 2006


Amphibians are cold blooded vertebrate that spend some time on land but must breed and develop into water. Frogs, salamanders and toods are amphibians. The word amphibians is derived from the greek word amphibia, which means “two lives.” Ampbibians are dependence on both aquatic and terrestrial habitat for survival. Other may be fully terrestrial, even if they born on land. Others may only need a moist habitat while others may be completetly aquatic. Amphibians are vertebrates animals. Temparature body of the amphibians is depend on the temparature of the environment. They have no skins which means amphibians skins is naked, lacking hair, feathers, or true scale, and is highly glandular with mucous and glandular glands. Amphibians eggs, lay are shell-less and must be deposited in humid environment due to avoid desiccation. Most species are found in tropical and subtropical environmentin south america, asia, and africa.

Most amphibians are biphasic, meaning that they go through aquatic stage and a terrestrial stage. Respiration constrains on single eggs and egg masses have affected the mode of amphibians reproduction in water and in air, because aquatic eggs require less oxygen and it develop faster, and hatch ealier.The Indian tree frogs, use the secretions and wiping behaviour to lower evaporation and it also relied on moist microclimate for endure prolonged survival away from water. Frogs are examples of amphibians as they live both in land and in water. During Amplexus, large masses of eggs are laid in water and those eggs are hatch in the water. Tadpoles are survive by eating small aquatic insects until they finally metamorphose.

The reason why the amphibians lived from aquatic to terrestrial environment:
Western toads as an examples of amphibians, adults feed on variety of terrestrial insects and arthropods, snails and slugs. Toads breed in january to july and leaving back eggs in strigs of over 16,00 in very slow moving water.
Western spadefoot, they prefer to stay in open grassland or woodland and produce eggs in seasonal stream. They spend much of time in burrows but are active on the surface.
The foothill yellow-legged, they are found mainly in permanet streams and occasionally found in back water habitats, isolated pools and slow moving rivers. Adult eat bothaquatic and terrestrial invertebrates especially insects. The foothill yellow-legged frog needs, shallow, slow flowing water with pebble substrate for breathing sites. 300 to200 clusters eggs are attached under water to substrate. Tadpoles requires water for 3 to 4 months before metamorphosis. They are usually vulnarableto many problems experienced in terrestrial.
Salamanders are amphibians, related to the frogs and toads. California slender salamanders habits in a valley-foothill hardwood and mixed conifer. It forages under or within surface such as decaying logs, pieces of bark or leaf litter an earthwormsit is commonly laid underground. California newts, it also occur in valley foothill, hardwood, and mixed conifer habitstsduring spring (septamber to may) they move into creek to mate and lay eggs. During summer the aquatic larvae are common in Big Chico Creek where they eat many small aquatic organism.

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. 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. 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.

Jennings.1996.Amphibians of the Big Chico Creek.[Online]. Available:[2006,May 11:20]
Linette Netshiheni
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