1) Surface area, particularly in relation to other aspects of organismal body fo
ID: 194335 • Letter: 1
Question
1) Surface area, particularly in relation to other aspects of organismal body form, has important implications for the physiology and therefore also ecology of many organisms. Discuss/explain two different examples from any of the material or animal groups we've discussed so far. You may choose any two examples, but they must illustrate different cases (e.g. Discussing the same phenomenon/function in two different organisms does not suffice.) In your discussion, describe the example (i.e. what is/are the features, organisms, etc) but also discuss the important implications for the organism(s). You may simple drawings (of your own) to supplement your answers, but you must explain the drawings. (Simply reproducing a drawing from elsewhere does not demonstrate that you understand its significance.) You must reference any sources you use, whether that is lecture notes, textbook, internet, or journal articles. The expectation is that this will require about 2-3 quality paragraphs in total (i.e. not 2-3 per example, but 2-3 in total for both). Rubric Example 1: Explanation of example (structure, organism if applicable); significance of surface area to "trait X" relationship; diagrams explained, if applicable; sources provided; written well free of glaring typographical/grammar/spelling errors; typed Example 2: Same, i.e. Explanation of example (structure, organism if applicable); significance of surface area to "trait X" relationship; diagrams explained, if applicable; sources provided; written well, free of glaring typographical/grammar/spelling errors; typedExplanation / Answer
Example 1: Porifera
Phylum Porifera [Lat.,=pore bearer] are a basal Metazoa clade as sister of the Diploblasts. The Phylum is divided into three classes Hexactinellida, Demospongiae and Calcarea. All adult sponges are sessile (nonmotile), and nearly all are marine; there are six families of freshwater sponges. They are multicellular organisms with their body full of pores and channels allowing water to circulate through them, consisting of jelly-like mesohyl sandwiched between two thin layers of cells. They are sedentary filter feeders which possess a well constructed and complex network of water conducting canals and choanocyte chambers which are lined with the flagellated choanocyte cells. Hence they can process water mass corresponding to their own mass every 5 seconds. Sponges fall into 3 groups based on body organization
1)Asconoids are small , simple forms with a tube-shaped body
2)Syconoids also have a tubular body whose wall is much thicker and highly folded into a series of incurrent canals that deliver water into radial canals lined with choanocytes.
3)Leuconoid:the largest and most complex ones and permits for an increase in body size
1 of 3 body patterns for sponges; spongocoel is folded canals, canals lined with choanocytes, increases surface area., small, with radial canals, extra surface area for more choanocytes.
Example 2: Cnidaria
Cnidaria is a phylum containing over 10,000 species of animals found exclusively in aquatic (freshwater and marine) environments: they are predominantly marine species. Mostly marine animals, the cnidarians include the corals, hydras, jellyfish, Portuguese men-of-war, sea anemones, sea pens, sea whips, and sea fans.The phylum Cnidaria is made up of four classes: Hydrozoa (hydrozoans); Scyphozoa (scyphozoans); Anthozoa (anthozoans); and Cubozoa (cubozoans). Only cnidarians manufacture microscopic intracellular stinging capsules, known as nematocysts or cnidae, which give the phylum its name. nidarians are radially symmetrical (i.e., similar parts are arranged symmetrically around a central axis). They lack cephalization (concentration of sensory organs in a head), their bodies have two cell layers rather than the three of so-called higher animals, and the saclike coelenteron has one opening (the mouth). Cnidarians have two body forms—polyp and medusa—which often occur within the life cycle of a single cnidarian. The cnidarians have large surface-area-to-volume ratio. All cells are preset at a short distance from the body surface. Therefore oxygen, carbon dioxide and nitrogenous wastes exchange by diffusion.
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