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Excretion and Osmoregulation Essay

In every aspect of an environment, there is a variance in the concentration of fluids present in the environment and the bodies of organisms. Osmoregulation is the regulation of water and ion concentrations in the body. Keeping this regulation precise is critical in maintaining life in a cell. Balance of water and ions is partly linked to excretion, the removal of metabolic wastes from the body. An animal’s nitrogenous wastes reflect its phylogeny and habitat Introduction:

Osmoregulation is the control of water content and the concentration of salts in the body of an animal. In freshwater species osmoregulation must counteract the tendency for water to pass into the animal by osmosis. Various methods have been developed to eliminate the excess such as contractile vacuoles in protozoans and kidneys in freshwater fish. Marine vertebrates have the opposite problem; these species prevent excessive water loss and enhance the excretion of salts with short tubules. In terrestrial vertebrates the dangers of desiccation are reduced by the presence of long renal tubules that increase the reabsorption of water and salts. Moreover, an osmoregulator is referred to as the state when body fluids whose concentration is different from that of their environment, so these organisms use up a lot of energy in having to control and gain water. An osmoconformer, is when body fluids with a solute concentration is equal to that of seawater. Furthermore, this report aims to identify the osmoregulator and the osmoconformer of the given species as well as to compare the specific gravity of each body fluid. Materials:

As per the BI108 lab 6 handout.
As per the BI108 lab 6 handout.

The Malpighian tubules function as an excretory system and aid in osmoregulation. The tubules empty into the alimentary canal, and remove nitrogenous wastes from the insect’s body. These structures were named for an Italian anatomist named Marcello Malpighi, who discovered the tubules in the seventeenth century. In Earthworm (pheretima posthuma), the excretory system is performed by segmentally arranged, microscopic, coiled, glandular & vascular & complicated excretory tubes, called as Nephridia. The Nephridia are found in all segment of the body of earthworm except the first 2 or 3 segment. According to the position & structure of Nephridia in the body, 3 types of Nephridia are found: Septal Nephridia, Pharyngeal Nephridiam and Integumentary Nephridia. The contractile vacuole controls the amount of water in paramecium.

Figure 2.0
Figure 1.0 displays the graph of specific gravity against concentration for P. lurca and U. coarctata. From the Figure 1.0 it can be seen that P. lurca is an osmoconformer in that the body fluid is equal to the concentration of seawater. Moreover, this means that the body fluid (internal fluid) is the same concentration as that of its surroundings. On the other hand, U. coarctata is depicted in the graph as seen by the plot as an osmoregulator. So, the body fluid has a solute concentration that is different from its surroundings. These suggest and confirm that the hypothesis is correct and it is quite evident as obtained in the results and graph plotted. Similarly, the body fluids collected (extracellular fluids) are known to be denser than water itself. To add on, the dissections of the various arthropods which included the cockroach, sipunculid and also the annelid, the earthworm. Earthworms and sipunculids have structures called nephridia for excretion, whilst cockroaches have malphigian tubules for excretion. Conclusion

In conclusion, in determining which organism was the osmoregulator and osmoconformer various other structures of numerous arthropods were also studied and analyzed. The hypotheses was indeed proven correct, as the P.lurca is the osmoconformer and U.coarctata is the osmoregulator. Osmoregulation is an important process in any animal as it assists in maintaining stable internal conditions in terms of water content and the concentration of ion soluble contents in any given body. Furthermore, as predicted by obtaining specific gravity would indeed determine the two types of osmoregulation, the organisms P.lurca and U.coarctata displayed different specific gravities that contributed in the decision. Hence, to reiterate, osmoregulation is a vital process that enables an animal’s survival as well as it contributing to the environment.


Martin, E. and Hine, R. (2008). Osmoregulation. Oxford Dictionary of Biology. (Web Link: http://www.oxfordreference.com/view/10.1093/acref/9780199204625.001.0001/acref-9780199204625) Bot, C. 2013 Sipuncula, Wikipedia encyclopedia, viewed on 24th September 2014, http://www.wikipedia.org Campbell, N and Reece, J and Mitchell, L and Taylor, M. 2003, Control of the Internal Environment, Biology- Concepts and Connections, Fourth Edition p.506, 507, Pearson Education Incorporation- Benjamin Cummings, San Francisco Hickman, C and Roberts, L and Larson, A I’Anson, H and Eisenhour, D, 2008, Integrated Principles of Zoology, Fifteenth Edition, McGraw Hill. Walker, R. L, 1993 ‘Using crustaceans to illustrate the principles of osmoregulation, Acid- base balance and respiratory physiology’ Tested Studies for laboratory teaching, Volume 7, p-149-178 Yintan 2013, Wikipedia encyclopedia, viewed on 20th September 2014, http://www.wikipedia.org Martin, E. and Hine, R, 2008, A Dictionary of Biology, Sixth edition, Oxford University, Great Britain. 2013, ‘Biology Notes: ‘Osmoconformers and osmoregulators’ Hadley, D., Malpighian Tubules, About Education viewed on 26th September, 2014 on http://insects.about.com/od/m/g/def_malpighian.htm Science (about Earthworm), (Web link: http://sachit.nepalscout.tripod.com/id1.html) Eukaryotes: Protists and fungi, BSCS Biology, 9 ed. Chapter. 12, pg. 328, viewed on 25th September, 2014 on http://books.google.com.fj/books?id=xC-WGtA7eP8C&pg=PA326&lpg=PA326&dq=contractile+vacuole+in+paramecium+function&source=bl&ots=1mI4GsePJi&sig=Yo2c_8IYaJ4Y

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