BIOL 111 Lecture 11: Annelids and Molluscs

• School: McGill University
• Department: Biology
• Course: BIOL 111
• Professor: Andrew Hendry

Document Summary

Sister species, closest relatives to one another. Based upon the two above, we infer bilaterally symmetrical and triploblastic. Feeding structure called lophophora" made of crowns of tentacles from ciliates. Similar rrna sequences, supported by molecular data. Segments are all similar, but are differentiated and modified based on function. Efficient nervous control, impulse can be sent straight to segment"s ganglion. Beneficial increase in body size, enables body regeneration. Also present in arthropods, vertebrates (e. g. spinal column segments) Well developed, anterior brain, sentimental ganglia, ventral nerve cord. Aortic arches=multiple hearts essentially, dorsal and ventral blood vessels. Crawling, burrowing, swimming, pelagic, tube dwelling, boring. Leeches are used as biological aids to increase blood flow. Has gills, or acts as lung (cavity) Modifications on ancestral body plan through adaptive radiation. Large adductor muscle to close its shell. Shell or no shell dependant on species. Mantle cavity and anus moved over head.