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Unformatted text preview: Protostomes Molluscus skeleton grows with the body - diverse Annelids earth worms easy to classify Arthopods skeleton development is different from Molluscus a million species, complex invertebrate diverse Eucoelomate body plan is the evolutionary big steps contribute to the success in protostomes Cleavage is spiral and Determinate Mouth develops at or near Blastospore (first opening of the embryo) Anus develops elsewhere Eucoelomate Schizocoely (largest and complex with diversification) huge adaptation for evolution Schizocoely the splitting of coelom during the early stage to line on all sides of mesoderm Arthopods not many segment more complex Well developed systems, complex nervous system, muscle, and behaviors Phylum Mollusca 110,000 species and 35,000 fossils Have three-part body plan o Visceral mass contains internal organs o Mantle may secrete shell and/or contribute to development of gills or lungs o Head-Foot muscle adapted for locomotion, attachment, or food capture, sensory reception o Foot muscles to creep forward slow moving animals o Reproductive system external fertilization, separate sexes Trocophore larva veliger larva (big flat like structure with cilia with a shell) adult Molluscs diverse (means soft body) o H.A.M hypothetical ancestral Mollusc - not exist o Nervous system consists of several ganglia connected by nerve cords o Coelom is reduced, and largely limited to te region around the heart o Heart pumps hemolymph through vessels into hemocoel Blood pumps into the opening, open circulatory system large volume in fluid under low pressure hemolymph - clear Connect to the gills where they get nutrients and oxygen Kidney to filter blood and waste usually ammonia most toxic for water organisms maintains the balance in the body such as ion Radula feeding apparatus is associated with head with teeth (distinct between mollusc species) gradually replace over time Complete digestive system gland to provide enzyme for digestive system Respiratory system gills with large surface area to exchange gas through water (tenidia) some modified into a lung for gas exchange The second distinct structure is the mantle folded and secrete the protective structure for the body o Shell Layers Periosrtacum conchiolin tough protein protects the inner layers of the cells Prismatic calcium carbonate take from the water to secrete the shell to grow bigger as the organism grows thick and it grows inside from the edges Nacreous calcium carbonate over protein mother of pearl gets thicker over time o HAM Bivalves (two plates), chitons (many plates to their shells, rocky surface roll up their teeth can hold on to rock because their teeth have iron in it ), monoplacophora (one plate,...
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