Introduction: Before tetrapods existed, all vertebrates were confined to living in aquatic habitats. The only animals that lived on land were arthropods. Through natural adaptations, the fish developed into amphibians. This colossal stage of change made necessary the evolution of new ways of breathing, locomotion, and reproduction. Paleontologists needed to understand how this transition took place.
The theory that cetaceans evolved from a goat-like being is not at all farcical. The similarities between the skeletal systems are more than coincidental. The only difference is that the cetaceans adapted to a marine lifestyle. The front limbs became modified as paddle-shaped flippers, the bones of which are still reminiscent of jointed limbs and digits, but the hind limbs were lost. The broad horizontal tail flukes that provide the main propulsive thrust bear no anatomical connection to the lost hind limbs, but are a seperate and distint development.
Or dialysis patients who may be facing kidney failure could receive new medicine that is guaranteed to work because it was ... ... middle of paper ... ...oples thoughts on this subject. Also, the effects are very devastating on the other hand when the damage that is done can be greater than the benefits. Works Cited "11 Facts about Animal Testing." Do Something. Do Something, n.d.
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... ... middle of paper ... .... An example of amphibian which is well adapted to living on land is true frogs in the order (Anura) and family (Ranidae). These structural characteristics include modifications in the inner ear. The inner ear consisted of pappilae and double transmission channels these helped to detect airborne sounds. The reasons for modifications in the ears were due to the fact that air is 1000 times less dense.
They must have gills or how would they be able to stay underwater for such lengthy periods of time? Could mermaids give birth to live offsprings without laying eggs? Possibly, but they are not mammals and can not sexually reproduce due to the lack of reproductive organs. Additionally, the species remains in pleasant habitats that provides sufficient light intensity and thermal conditions. Allowing humans to witness the supernatural beings in plain sight.
There are differences between bone structure and hard tissues of living modern humans to those of chimpanzees and bonobos (Boer, 2005). Speech is a unique trait that only humans so far have developed. This trait was most likely a prerequisite for the development of culture within human society. Throughout society, it has been shown that speech can vary from being extremely complex to astonishingly simple. Finally, the way infants acquire speech has become more well known helping provide the starting point of evolution of speech.
The respiratory system is essential for life as it allows gas exchange in organisms. Respiratory systems are not all the same though; an organism’s respiratory system is typically unique to the environment they are living in. Along with this movement is another factor that affects the type of respiratory system in an animal. Gills for example allow fish and other gilled animals to take in oxygen from the water, but sharks gills are different from a fish’s gills. Sharks gills do not push water through automatically like that of a fish so they have to keep swimming in order to breathe (Raven, 2011).
If animals were not used in medical research, we might still be living in a world where we must fear diseases like polio, smallpox, and even measles. Human Benefits. Medicine alone is not the only thing that has been vastly improved due to animal testing, the way we treat diseases and surgeries has all drastically changed and improved.
Contrary to primary belief, dogs, cats, and primates only account for .02% of overall testing. Primates, because they share 99% of human DNA, are used to study neurodegenerative disease such as Alzheimer's. Animal testing, although seen as inhumane and unnecessary, should remain a necessary form of experimentation for medical science. Animal testing is becoming increasingly more humane. Scientists have discovered that the stress put on larger animals such as primates, dogs, cats, and rabbits, can alter test results.
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.