Extinction of Frogs an Indicator of a Declining Planet?
Are The Threatened and Extinction Of Frogs An Indicator Of A Declining planet?
Outline
I. Introduction
Thesis Statement: Is the amphibian disappearances or deformities an early warning of serious environmental problems?
II. Origins
a. Early
b. Evidence
III. Habitat
a. Ecosystem
IV. Indicator
a. Detection
V. Disappearance
a. Arizona
VI. Why?
a. Diseases
b. Pollution
VII. Frogs
a. Endangered
b. Threatened
VIII. Conclusion
Disappearance of Frogs
Amphibian populations are declining or are disappearing around the world. Scientists are impetuously searching for clues as to why there is a decline in our frog species. In existence for over 350 million years, frogs have survived through the age of the dinosaurs and through the mass extinction of those dinosaurs. Why now, are the populations of a unique, colorful species declining in rapid numbers? Some scientists believe that ultraviolet radiation is the cause. Others are blaming the toxic substances so easily discarded every day by large companies. Scientists have found that many deadly virus infections and a chytrid fungus’ are the cause of die offs.
Amphibians have been in existence for over 350 million years. They were once fish, aquatic dwelling animals, and were the first vertebrates to evolve from water to land. Amphibians survived both the dinosaur age and the mass extinction of the dinosaurs. According to Neil Shubin of the University of Pennsylvania, there is evidence of frogs living in the Jurassic period around 200 million years ago. A fossilized skeleton dug up in 1982 in Arizona, was found in a layer of rock known to be from the Jurassic period.
Wetlands are their primary breeding habitat, but forests are where they spend most of their non-breeding season. Amphibians have an ecological importance in both fresh water and terrestrial habitats. They are both predators and prey, and constitute great biomass. The role of the amphibians on wetlands or terrestrial ecosystems is not clearly defined; however, ecologists are investigating their significance in the environment.
Since frogs breathe either partially or wholly through their skin, they are considered an indicator that the ecological balance is changing. They are exposed to the environment completely all the time and are more vulnerable than a human, detecting changes in the environment before any human has any indication of what is happening. Other factors making them a prime indicator is the fact that they dwell both in water and on land and they store contaminates, causing a high concentration of toxins to be found in their fatty tissues. This concentration can be...