Phylum Porifera Essay Example | Topics and Well Written Essays - 1250 words

Phylum Porifera - Essay Example The sponges were considered to be plant-animal classification until 19th Century because they were not able to move, especially during their adult life where they attach themselves to a rock. However, this paper aims to evaluate in a critical aspect about the notions that Phylum Porifera is paraphyletic rather than monophyletic. The essay achieves its purpose by providing credible sources to demonstrate the comparative knowledge of morphology and embryologoy in an effort of evaluating the suggested hypothesis. The paper demonstrates the suggestions of the notion in respect to bilaterian’s ancestors. The sponges are among the simplest animals in the Kingdom Animalia. Their feeding system is unique among other types of animals. However, the evolution of animals is believed to transform the sponges from their earlier form of multi-cellular organisms to the present day animals. As earlier mentioned, it is learnt that Poliferans had an early branching event, which resulted to their separation from other metazoans. The sponges differentiate themselves from other animals in different nature such as lacking digestive, nervous, and circulatory systems. On their side, they adapt themselves by maintaining the constant flow of water through their pored bodies in order to get oxygen and food, as well as removing waste from the body. In addition, their shape of the body is adaptive to maximal reliability of water flow though their central cavity, where it uses a hole called osculum to deposit the nutrients. Most of the sponge species feed on the food particles or bacteria in the water, where some of them host micro organisms for photosynthesizing processes to act as endosymbionts. Such associations ensure there is maximum production of oxygen and food in the water, as compared to what they consume. However, some sponges that live in environment with small or no food have become carnivores since they mainly prey on

Mass Media and the Impact of Violent Imagery on Teens Essay

Mass Media and the Impact of Violent Imagery on Teens - Essay Example Within this context, one must learn to see media as more than just entertainment. It is also a library, a channel of communication and a means of self-betterment. In other words, teenagers must be guided toward a better understanding of mass media specifically because its function in society is subjective and undefined. Teenagers who are guided toward a broad utilitarian view of the media are more apt to use it responsibly and are less likely to exhibit negative behavior than those who are exposed indiscriminately to violent video games, programmes and films. Those who criticise the culture of violence that unquestionably proceeds from films, television, the Internet and video games have quite successfully leveraged the impressionable vulnerability of youth. However, this ideological position, which is now widely accepted, underestimates the capacity of teenagers for independent thought and reason. ‘The systematic derision of children’s resistant capacities can be seen a s part of a broader conservative project to position the more contemporary and challenging aspects of the mass media, rather than other social factors, as the major threat to social stability today’ (Gerbner 1993, p. 139). This tendency to emphasize the negative end of the spectrum, which is apparently enhanced every time a young person perpetrates an act of violence, is the rallying cry of interest groups and politicians seeking to prove a point. These factions have benefited from the published opinions of scholars and theorists who warn against the terrible residual effect of violence in the media on young people. George Gerbner, a communications professor, and social scientist, wrote that while there have been bloodier eras in human history, none have been so filled with violent imagery as the present: ‘We are awash in a tide of violent representations the world has never seen. There is no escape from the massive invasion of colorful mayhem into the homes and cultura l life of ever larger areas of the world’ (Gerbner 1993, p. 139). Gerbner and others associate violence with power, the acquisition of which is of keen interest to people of all ages. For teenagers, exercising power in the ‘virtual’ world of video games is an elaboration of personal power that is otherwise beyond the reach of young people. Gerbner argues that violent behavior among young people should be studied from the standpoint of the ‘cradle-to-grave’ violent imagery with which young people are bombarded. It is not perceived, isolated causes of violent acts that should be considered, Gerbner claims, but other less apparent factors to which pervasive media violence has contributed. He holds that the uniquely modern phenomenon of media-produced violence has engendered unconscious, deeply rooted feelings of vulnerability and personal insecurity and that it is this, more than anything, that produces aggressive and violent behavior in teenagers (Gerb ner 1993, p. 139).