1500_12_Molluscs - BIO1500 W07 Mollusca

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Unformatted text preview: BIO1500 W07 Mollusca http://www.mblwhoilibrary.org/exhibits/leuc kart/wall_charts/slide_index.html Mollusca basic facts ! >110,000 described species ! 0.5mm-21m (giant squid) ! Primitive groups marine, but many terrestrial ! Eucoelomate protostome phylum Giant squid from Logy Bay, Newfoundland in Reverend Moses Harvey's bathtub, November/December, 1873 http://en.wikipedia.org/wiki/Giant_squid Mollusca represent one of the largest animal phyla Mollusca Chordata Arthropoda Platyhelminthes Nematoda (?) Porifera Annelida Echinodermata Sarcomastigophora Apicomplex Ciliophora ~1,000,000 MOLLUSCA: classification 1) Polyplacophora: chitons (~500 chitons species) 2) Gastropoda: snails (~40,000 Gastropoda species) 3) Bivalvia: clams, oysters (>100,000 species) 4) Cephalopoda: squids, octopus Cephalopoda (~600 species) Evolution of mollusc body plan diversity Evolution Defining body plan traits of Molluscs 1. Subdivision into three body regions: head, visceral mass (visceral, excretory and reproductive), foot (movement) Visceral mass Mantle cavity Mantle Foot Defining body plan traits of Molluscs 2. Head Cerebral ganglion Radula Stomach and digestive gland Defining body plan traits of Molluscs 5. Radula: rasping, tongue like organ used for feeding http://www.gireaud.net/images/snail_radula.jpg Defining body plan traits of Molluscs 5. Radula: rasping, tongue like organ used for feeding Radular muscles Radular muscles Radula Odontophore Odontophore muscles Odontophore muscles Mouth Defining external body plan traits of Molluscs 5. Radula: rasping, tongue like organ used for feeding Radular teeth Radular teeth Defining body plan traits of Molluscs 5. Radula: rasping, tongue like organ used for feeding http://www.gireaud.net/images/snail_radula.jpg http://molbiol.ru/pictures/80805.html Defining body plan traits of Molluscs 3. Visceral mass housing visceral, excretory and reproductive organs Pericardial cavity Gonad Metanephridium Stomach and digestive gland Defining body plan traits of Molluscs 4. Mantle: outer protective tissue fold that may secrete a hard proteineacous or mineral shell (not in all species) Mantle Mantle cavity Gills Defining body plan traits of Molluscs 6. Foot: muscular ventral substrate contact organ that can be modified into tentacles or “water wings” Foot Class POLYPLACOPHORA: chitons metameric body plan Flattened oval body with 8-plate shell Radula functions as scraping organ to harvest algae from rock Class POLYPLACOPHORA Class metameric body plan Flattened oval body with 8-plate shell Radula functions as scraping organ to harvest algae from rock Mouth Mantle cavity Gills Foot Anus Class POLYPLACOPHORA metameric body plan Flattened oval body with 8-plate shell Radula functions as scraping organ to harvest algae from rock Digestive gland Mouth Stomach Gonad Pericardial cavity Nephridium Anus Class GASTROPODA: sea slugs, snails Class ~40,000 species marine or terrestrial Single shell that can be coiled or spiral Radula used for rock grazing Marine species possess gills Terrestrial species utilize mantle cavity as lungs Class GASTROPODA: sea slugs, snails Class GASTROPODA: sea slugs, snails Class Chelidonura varians Eliot, 1903 http://www.medslugs.de/E/Pac-W/Chelidonura_varians_05.htm Class GASTROPODA: sea slugs, snails Chelidonura varians Eliot, 1903 http://seaslug.info/display.cfm?id=9980 Class GASTROPODA: sea slugs, snails Class Tethys fimbria http://www.seaslugforum.net/showall.cfm?base=tethfimb Class GASTROPODA: sea slugs, snails Chromodoris geminus http://img.photobucket.com/albums/v297/Pufferfishy/BlogLink/Sea%20Slug%20Madness/Cgeminus.jpg Class GASTROPODA: sea slugs, snails Class huridilla gracilis (Risbec, 1928) http://img.photobucket.com/albums/v297/Pufferfishy/BlogLink/Sea%20Slug%20Madness/Tgracilis.jpg Class GASTROPODA: sea slugs, snails Flabellina rubrolineata (O'Donoghue, 1929) http://www.seaslugforum.net/factsheet.cfm?b ase=flabrub Class GASTROPODA: sea slugs, snails Torsion: mantle cavity and anal opening move from posterior to anterior. Torsion occurs during development as one of the lateral muscles grows faster than on the other side. Torsion Anus Anus Mouth Foot Class GASTROPODA: sea slugs, snails Class Torsion: mantle cavity and anal opening move from posterior to anterior. Torsion occurs during development as one of the lateral muscles grows faster than on the other side. Example of right-handed torsion: Mouth Mouth Heart Anus Gills Mantle cavity Mantle Mantle cavity cavity Gills Anus Heart Class GASTROPODA: sea slugs, snails Torsion: mantle cavity and anal opening move from posterior to anterior. Torsion occurs during development as one of the lateral muscles grows faster than on the other side. Left-handed snail Right-handed snail http://www.creativegeniusonline.com/Ann%20Carol%20Snail%20earrings%20low.jpg Class GASTROPODA: sea slugs, snails Class Torsion matters for predators Class GASTROPODA: sea slugs, snails Torsion matters for predators Class GASTROPODA: sea slugs, snails Class Torsion matters for predators Class GASTROPODA: sea slugs, snails External morphology Shell Anus Foot Pneumostome Tentacle (Eye stalks) Tentacle Mouth Genital pore Class GASTROPODA: sea slugs, snails Class Digestive tract Digestive gland Intestine Anus Crop Salivary gland Mouth Class BIVALVIA: clams, scallops, mussels, oysters ~950,000 marine and 500 freshwater species Equipped with two shells hinged dorsally and pulled together with adductor muscles Head and radula reduced Filter feeding through specialized appendages (palps) and gills - Class BIVALVIA: clams, scallops, mussels, oysters Class External morphology Hinge Labial palp Labial alp Gills Excurrent siphon Foot Incurrent siphon Class BIVALVIA: clams, scallops, mussels, oysters Anatomy of visceral mass Pericardial cavity Heart Intestine Excurrent Stomach Incurrent Intestine Gonad Class BIVALVIA: clams, scallops, mussels, oysters Class Circulatory system Pericardial cavity Artery Heart Atrium Artery Gills Foot Class BIVALVIA: clams, scallops, mussels, oysters Locomotion Class CEPHALOPODA: squids, octopus Class ~600 marine species Rudimentary shell serving as endoskeleton Foot modified to tentacles Anterior tentacles modified to pincer fancs in mouth regions Locomotion by walking or jet propulsion Exceptionally well developed visual organs Octopus can change body coloration Class CEPHALOPODA: squids, octopus Morphology Tentacle (2) Arm (8) Funnel (siphon) Collar Eye Fin Class CEPHALOPODA: squids, octopus Class Anatomy http://www.njscuba.net/biology/images/anatomy_squid.gif Class CEPHALOPODA: squids, octopus Class This specimen, an immature female, was caught at 760 m (2500 feet) in the Antarctic off Dronning Maud Land by t h e S o v i e t t r a w l e r E u r e k a ( _ _ _ _ _ _ ) in 1981. Photograph by Alexander Remeslo.[1] Class CEPHALOPODA: squids, octopus Colossal Squid (Mesonychoteuthis hamiltoni) caught in the Ross Sea. Probably the largest specimen ever recorded, close to the maximum estimated size for the species. http://en.wikipedia.org/wiki/Image:Colossal_Squid_Ross_Ice_Shelf.jpg Class CEPHALOPODA: squids, octopus Class Colossal Squid (Mesonychoteuthis hamiltoni) caught in the Ross Sea. Probably the largest specimen ever recorded, close to the maximum estimated size for the species. http://en.wikipedia.org/wiki/Image:Colossal_Squid_Ross_Ice_Shelf.jpg Class CEPHALOPODA: squids, octopus Complete specimen caught in 2003. http://en.wikipedia.org/wiki/Colossal_squid Class CEPHALOPODA: squids, octopus Class ...
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This note was uploaded on 08/03/2010 for the course BIO 1500 taught by Professor Pandolfi during the Winter '08 term at Wayne State University.

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