1. Write an essay that discusses what biodiversity means and how it has been affected by natural and man-made pathways. Your essay should be approximately 500 words in length with references in APA format.
Biodiversity means that there is a variety of different forms of life. The word bios stands for life while the world “diversitas” stands for variety. Biodiversity means that different forms from a variety of families and species exist in different ecosystems. Biodiversity can take the form of genetic, species diversity level and ecosystems level. This also means that biodiversity also stands for preservation of that type of diversity in comparison to a single species, such as humans, taking over a large proportion of land and habitat. This also means that humans should devote efforts to protect this variety of life in the world and preserve the diversity of species living among us. On another level, biodiversity stands for the problem of decreasing species in the world due to human activity (“Biodiversity, 2011).
There are many ways biodiversity has been affected by natural and man-made methods. Natural methods of decreasing biodiversity has been climate change. Global warming affects ecosystems as well as the species within the ecosystem. For example, the Arctic is especially affected by global warming and climate change. As the climate changes, species lose their ability to adapt to changing conditions such as warmer temperatures and much more extreme weather exams. Changing rain and drought can also affect a species ability to survive in a new environment. Species such as whales have adapted their entire lives to live on ice and form 25% of the Arctic Ocean’s production. Their destruction, in turn, affects the other in their food chain who eats and co habitats with a single species’ survival. Therefore, the survival of algae affects the survival of the polar bear up the food chain. This in turn decreases biodiversity overall, even if it does not affect one species directly (“Climate change affects biodiversity,” 2011).
Man made pathways that can decrease biodiversity include logging, hunting and other pressures humans place on their environment. In order to create space, humans have destroyed countless habitats of many species and taken away entire ecosystems. To create homes, humans also log forests, which preserve many species and populations. Lastly, humans also hunt species in many cultures, such as in Asia, where tigers and other rare animals are used to make medicine. Pharmaceutical companies are also exploring options of creating medication from other rare species such as diclofenac from vultures. This creates additional pressure on maintaining biodiversity among other human wants and needs. As a result, biodiversity is decreasing in many populations around the world. Sport hunting is considered to be one of the main reasons that lions are significantly dwindling while other animals such as tigers, leopards and deer are hunted for their skin. This makes rare animals more valuable and therefore more susceptible to extinction. In areas where habitats are being encroached on by humans, animals such as amphibian populations, are experiencing starvation and loss of protection and home (“Climate change affects biodiversity,” 2011).
2. There are nine major animal phyla. Choose two phyla that you find particularly interesting. Give common examples of each phylum and distinguish among them relative to types of tissues/tissue layers (none, diplobastic, triplobastic), body symmetry (assymetrical, radial symmetry, and bilateral symmetry) and presence and type of body cavity (acoelomate, pseudocoelomate, coelomate). Be careful not to confuse digestive cavities with body cavities. They are very different things. Briefly, discuss why the phyla would be similar or different for these characters based on evolutionary relationships and environmental influences. Answer should be a least 3 paragraphs in length.
Two major animal phyla I find interesting are Porifera, which are sponges, and Cnidaria, which consists of Hydra, Anemones and Jellyfish. They are similar in that they both lack organs. However, the level of organization in a sponge is cellular while Hydra, Anemones and Jellyfish is on a tissue level. Both species have similarities in sexual and asexual reproduction abilities as well as absent circulatory, respiratory and excretory systems.
However, sponges have absent germ layers as well as absent symmetry, cephalization, body cavity and segmentation. They are supported by an endoskeleton that consists of spicules. They also have a intracellular digestive system. Hydra, Anemones, and Jellyfish have two germ layers as well as radial symmetry. They also have a nerve net nervous system and a hydrostatic skeleton. However, they have a gastrovescular cavity for a digestive system while others have an intracellular digestive system (Audesirk, 2011).
The similarities for the phyla of Porferias and Cnidarias arise from the fact that they are invertebrates with limited motion. As a result, many of the specialized labor and complex systems are not necessary for their survival. They also both live underwater in a very similar environment, leading to the developmental similarities in lack of circulatory, respiratory and excretory systems (Audesirk, 2011).
3. Discuss the characteristics that define humans as belonging to the phylum Chordata. How do these characteristics change after the embryonic stage of growth? Answer should be a least 3 paragraphs in length.
Humans belong to the phylum Chordata because Chordata has the characteristics of vertebra. We have an organ system and bilateral symmetry as well as a digestive, circulatory, respiratory and excretory system, making up a complex species with functioning internal systems. We also have three germ layers as well as sexual reproduction, separating us from Echnidemata and Porifera(Audersik, 2011).
These characteristics change after our embryonic stage of growth due to changes in human structure. Bilateral symmetry in humans change after the embryonic stage due to the positioning of the organs. For example our heart is located to the left and our anatomy is not a true mirror image. Another characteristic that changes after the embryonic stage would be that we have reduced segmentation, which is common in other species (Audersik, 2011).
However, humans still belong to the phylum of Chordata due to the high level of organization, our germ layers of endoderm, ectoderm and mesoderm as well as the complexities of our body systems, such as a digestive system that separates the mouth and the anus. We also have kidneys in our excretory system, which differentiates us from Echnodermata who have absent excretory systems, Insects, who have excretory glands and Snails who have nephridia as their system (Audersik, 2011).
Audesirk, G. (2010). Biology: life on earth. New York, NY: Benjamin-Cummings Pub Co.
Biodiversity. (2011, May 24). Retrieved from http://www.biodiv.de/menue1/encyclopedia/biodiversity.html?L=1
Climate change affects biodiversity
. (2011, May 24). Retrieved from