BIO 2135 Lecture 2: Form and Function Notes for Midterm 2
20 Apr 2017
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Fun facts: are a part of the locotrophozoa. Includes earthworms, leeches, spoonworms and beardworms: found in freshwater, marine and wet terrestrial environments, predatory on the substrate that surrounds them. Ancestral characteristics and changes: ancestrally all metameres had paired metanephridia and a ganglion that was capable of producing gametes and therefore could act as its own organism. Symmetry: bilaterally symmetric each metamere, head is composed of the prostomium, peristomium and pygidium= not actually true segments though, homonomous segments: no difference in the segments down the length of the body. Respiration: gas exchange occurs across the body wall (some species have gills), large ones might have respiratory pigments to increase the oxygen carrying capacity. Metabolic waste: use diffusion across their epithelium. Reproduction: monoecious and dioecious, trophophore larvae differentiates into sections from the front to the back where each segment has its own mesoderm that differentiated from the schizocoel, hermaphrodidic.
