exam3 - ← Protostomes • Molluscus – skeleton grows...

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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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exam3 - ← Protostomes • Molluscus – skeleton grows...

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