Abstract
This paper examines how amphibians have not been exploited by humans like other animals have, they are kept as household pets and in some countries their flesh is seen as quite a delicacy. It therefore attempts to understand why are so many amphibian populations are in decline around the world. It shows how in some areas of the globe the decline is evidently due to loss of habitat but how in other areas, the reasons could be attributed to factors such as the depletion of the ozone layer or pollution. It looks at the advantages of amphibians to humans such as their use as environmental indicators and the use of their toxins as pain killers and covers methods of conservation.

From the Paper
"Habitat loss seems to be a significant cause of the diminishing amphibian populations over much of the world. Human population growth has led to many of the wetlands that are essential for amphibians to be drained for agriculture, filled in or paved. In Britain alone, many years of draining wetlands in order to improve crop yields has resulted in the destruction of 82% of marshland. Now, only isolated patches remain. Deforestation is an added strain on amphibians as the dense canopy provides shelter and protection for not only the adult amphibians but also their developing young, from predators and ultraviolet light."

Tags:ozone, layer, habitat, ecology, medication, environment

From the Paper
"The Decline of the Amphibians
During the last 20 years, scientists worldwide have begun to notice some disturbing trends among amphibian populations. Moreover, the most troubling changes have occurred within the last decade. It seems that certain of the globe's 5,130 amphibian species have rapidly declined in number. Several species, in fact, may have already become extinct. To date, researchers do not know the reasons for this occurrence. However, some believe that atmospheric ozone depletion is responsible for the animals' decline. It could be that different amphibian species are highly vulnerable to ultraviolet radiation. Regardless of the underlying mechanisms though, the amphibians' plight may have serious implications. As "indicator" species, their decline could foretell major future environmental problems."

Abstract
The paper begins by listing the frog's external characteristics and order of taxonomy. It continues to describe its physiology. It studies the behavior of the frog, dividing this topic up into behavior (including a look at its biological clock), learned behavior and social behavior. The paper includes a picture of the frog.

From the Paper
"Rana boylii sierrae Camp. or foothill yellow-legged frog is found mostly in rivers and riverbanks, hiding around the rocks or emerges for sunlight. Ashton et al. writes that the species is morphologically identified in about 37.2 - 82.0 mm adult size, with dark and light gray dorsal color with some brown or red spots, much vague in the juvenile appearance. It is described that Rana boylii has "rough skin, inconspicuous tympanum, horizontal pupils, fully webbed hind feet, poorly developed dorsal lateral folds, lack of dorsal stripe, and lack of black eye mask."

Tags:external, characteristics, appearence, taxonomy, physiology, behavior, innate, learned, social

Abstract
This paper discusses how fire has historically played an important role in creating and maintaining ecosystems across the United States, especially in prairies and forests. In particular, it looks at how, in areas where fire has been suppressed and non native plant species have intruded prescribed fire is often used to attempt to restore natural habitats and how this can increase the natural habitat available to herpetofauna. The effects of fire on herpetofauna in a tallgrass prairie are compared to that on herpetofauna in various forest ecosystems. The paper concludes that in both ecosystems, the benefit of prescribed fire to the entire community outweighs the negative effects to the herpetofauna and that land managers must know the amphibians and reptiles that live in each community, their seasonal activity, and their habits in each area to most effectively conduct prescribed burns to restore their natural habitat. This paper contains tables.

From the Paper
"Fire has served an essential role in fire-dependant ecosystems, such as prairies and forests, for thousands of years (Axelrod, 1985; Swetnam and Baisan, 1996; Dale, 2006). Prairies can be found in areas too moist for desert and to dry for forests. Prairie ecosystems vary according to the environment, including soil type, water, grazing and fire (www.nps.gov, 2010). One specific ecosystem within prairies dependent upon fire is the tallgrass prairie. Tallgrass prairies once covered over 140 million acres across North America (www.nps.gov, 2010). Today only 4% remains. The largest area of tallgrass prairie remaining in the United States is in the Flint Hills, which stretches through eastern Kansas from the Nebraska border into north-eastern Oklahoma (Anderson, 1990). Historically, fire was a common in all prairies and occurred in tallgrass prairies every 2-3 years in the early spring (Collins and Gibson, 1990). The burning of the tallgrass prairie increases plant productivity, decreases litter on the ground, and decreases woody vegetation (Wilgers and Horne, 2006). Humans have altered this natural pattern of burning in prairies."

Tags:ecosystems, natural, habitats

Abstract
This paper provides an explanation of the evolutionary development of the circulatory, respiratory, digestive, sensory, and integumentary systems of phylum chordata. Comparisons between the systems various classes of phylum chordata are made, and the evolutionary advantages of the higher classes are highlighted. The paper is also accompanied with relevant diagrams and figures.

Outline:
Circulatory System
Evolution of the Heart
Piscine Heart
Amphibian and Reptilian Hearts
Avian and Mammalian Hearts
Respiratory System
Respiration in Agnatha and Chondrichthyes (Gills)
Respiration in Osteichthyes (Gills)
Respiration in Amphibians (Gills, Skin, Lungs)
Respiration in Reptiles, Birds, and Mammals (Lungs)
Digestive System
General Trends in Evolution of the Digestive System
Ruminant Stomach
Avian Gizzard
Sensory System
Usage of Olfactory System and Usage of Visual System
Prevertebrates: An Introduction
Anamniotes
Amniotes
Integumentary System
Anamniotes
Amniotes

From the Paper
"One of the most fascinating developments made by the vertebrates was the heart. The complex and efficient four-chambered pumping mechanism possessed by mammals and birds evolved from what was only a muscular artery in protochordates. The heart itself is a specialized muscle responsible for circulating blood through the blood-vascular network. Marine protochordates possessed little more than a muscular region near the base of the aorta because, virtually anywhere on their bodies, they were capable of exchanging O2 and CO2 through their relatively thin skin. When scales and thicker skin emerged, however, this capability was lost, and respiration was localized in the pharyngeal region. An effective pumping device was required, and thus, the heart evolved."

Tags:integument, circulation, sensory, system, respiration

Abstract
This paper will discuss the nature of the poison arrow frog, and seek to understand why it is now becoming endangered. By looking into the habitat of this amphibian, we can learn why this animal is in endangered from extinction.

Abstract
This paper explains that osmosis is the movement of pure solvent from an area of low solute concentration to an area of high solute concentration through a semi-permeable membrane. The paper then explains the hypothesis of an experiment that the amount of salt dissolved in water affects osmosis in model frog skin cells. The paper also examines the major mechanism of water reabsorption in amphibians.

From the Paper
"The hypothesis for this experiment was that the amount of salt dissolved in water would affect osmosis in model frog skin cells. The prediction for this hypothesis is that the more salt that is dissolved in the water, the smaller the amount of water that will move into the cell. This would naturally result in an imbalance of the natural physiological ionic concentration of the amphibians and dehydrate them. The expected response would be an endeavor on the part of the animal to maintain its hydration which usually takes place through the skin and not through drinking as in vertebrate mammalian species, where the hypothalamus plays a role in triggering the drinking response when the animal is dehydrated. Experimental data suggests that the major mechanism of rehydration in the amphibian species is through skin and not through the process of drinking water (Bentley & Yorio, 1979). "

Tags:semipermeable, membrane, stratum, epithelium

Abstract
The following paper discusses the issue of genetic cloning by looking at its origins and scientific advances.The paper examines the research on genetic engineering and cloning that was used to clone plants, unicellular organisms, amphibians and simple mammals. It looks at significant advances in agriculture, industry and medicine. Although there are many potential benefits to this technology, the prospect of cloning humans has raised many practical, ethical and religious dilemmas that are discussed in this paper.

From the Paper
"Genetic engineering is the changing of an organism's DNA, genetic material to eliminate unwanted traits or to produce desirable traits. The earliest form of genetic engineering dates back to the scientist Gregor Mendel who did experiments with peas. He bred only the peas with the most desirable traits in order to achieve a healthier and stronger pea (McCuen 8). This method, called selective breeding, is still used today with plants and animals in order to increase food production. Corn plants are selectively bred in order to produce a larger tastier kernel. Another type of genetic engineering called hybridization or crossbreeding involves breeding animals of different species in order to obtain the most desirable traits of both. Male donkeys are crossbred with female horses to produce mules, which are good work animals (Levine 1). Genes are made of DNA, deoxyribonucleic acid. The discovery of DNA in 1953 by Drs. Watson and Crick led to a much better understanding of the structure and function of genes. Since that scientific discovery many scientists have developed techniques to manipulate the DNA in genes in order to control different genetic processes. In the 1970s, scientists discovered restriction enzymes, which are enzymes that are able to cut and splice DNA. This led to the scientific technique known as recombinant DNA, which has paved the way for more sophisticated types of genetic engineering (McCuen 8)."

Tags:cloning, dna, genetic, human, techniques, genetic, engineering, scientists, complex, mammals, possibility, humans

Abstract
This paper studies the Great Basin Spadefoot species and looks at where they can be found in the world. The writer discusses conditions and habitat for the Great Basin Spadefoot and describes their eating and living habits. The writer describes features of the species, including hibernation, reproduction, danger of extinction and various aspects of the spadefoot life. In this article, the writer discusses research and studies that have taken place regarding the Great Basin Spadefoot including mention of a large-scale collapse of an entire community of frog species and growth experiments. The writer makes use of the writings and studies of biologists and other experts to provide this insight into the spadefoot world.

From the Paper
"Within the United States, the Great Basin Spadefoot lacks special state or federal status. They occur throughout the Columbia Basin and are locally common in many areas and within Washington state, there have been no declines documented. Spadefoots apparently can tolerate some habitat alteration, which often persists in irrigated agricultural lands. Moreover, it is believed that they may have actually increased in abundance due to the prevalence of breeding sites provided in some areas by irrigation water, however no systematic surveys have been conducted to document such patterns."

Tags:frog, amphibian, toad, tadpole

Abstract
This paper takes a look at the Permian and Cretaceous-Tertiary periods of life on Earth - pre-historic forms of life from sea creatures to land and air creatures. During both of these periods, mass extinction occurred and a comparison of these two extinctions is documented in this paper.

From the paper:

"From the perspective of daily human life, we often think of tragedy on the level of individual death and destruction, and the concept of mass extinction as being confined to a species or at worst, an ecosystem. However, over the course of the existence of the earth, the planet has weathered many greater catastrophes. Geologists must take a much longer-term perspective of catastrophe when studying extinction. This paper will compare and contrast the Permian and Cretaceous-Tertiary mass extinctions."

Tags:dinosaur, marine, reptile, amphibian, ocean, terrestrial, nature, organic, volcanoe, demise