zoo 115 invertebrate zoology mollusca. mollusca – classes monoplacophora aplacophora...
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ZOO 115 Invertebrate Zoology
Mollusca
Mollusca – Classes
Monoplacophora Aplacophora Polyplacophora Gastropoda Bivalvia Scaphopoda Cephalopoda
animaldiversity.ummz.umich.edu/site/resources/Grzimek_inverts/Monoplacophora/Laevipilina_antarctica.jpg/medium.jpg
Mollusca – Class Monoplacophora
Resemble the generalized mollusc
Small (3 mm), flattened molluscs that inhabit deep water
Present in the Cambrian period – thought to be extinct until 1952
Single shellwww.manandmollusc.net/advanced_introduction/Images/Monoplacophora2.gif
Foot
Gills
Anus
Mouth
MantleMantle Cavity
http://www.labsis.usc.es/workshop/images/common/2.jpg
Mollusca – Class Aplacophora
~ 300 species Small benthic dwellers
between 200-7000m Shell-less
Secrete calcareous spicules on epidermis
Foot reduced or absent No eyes, tentacles,
statocysts, or nephridia
www.manandmollusc.net/advanced_introduction/aplac.html
Mantle Cavity
Gills
Pedal groove or foot
Mouth
Mollusca – Class Polyplacophora
~800 sp Ancient (since late
Cambrian) Lives in rocky-
intertidal region Has series of
plates for a shell. It is an herbivore
(except for one species)
http://www.ucd.ie/cobid/chitons/glossary_images/2002a0404131-c.jpg
http://www.ucd.ie/cobid/chitons/glossary_images/2002a0404135-b.jpg
Mollusca – Class Polyplacophora
Mollusca – Class Gastropoda Marine and terrestrial 2nd largest class in
animal kingdom Hard shell (most)
Mollusca – Class Gastropoda variety
Mollusca - Class Gastropoda Herbivores and
predators. Has a radula Hard shell (most) Well developed
head and cephalic tentacles
Locomotion – peristalsis of foot.
http://www.pirx.com/gallery/albums/mollusks/radula.jpg
/www.ling.helsinki.fi/~simon/gallery/snails
Mollusca – Class Gastropoda Anatomy
Mollusca – Class Gastropoda - foot
How can it do both?
/www.sfu.ca/~msr/Papers/BISC/images/nucelladesiccation
Columellar muscle
Tarsos muscle
Columellar muscle Retracts head and foot
into shell Extends head and foot Twists foot
Tarsos muscle Bottom of foot and edges Locomotion Prey capture Molding of eggs
No fluid filled hemocoel
Mollusca – Class Gastropoda Shell Coiling
http://www.cartage.org.lb/en/themes/Sciences/Paleontology/Paleozoology/FossilMollusks/AboutAmmonites/enroulement.jpg
http://www.cartage.org.lb/en/themes/Sciences/Paleontology/Paleozoology/FossilMollusks/AboutAmmonites/enroulement.jpg
http://content.answers.com/main/content/wp/en/a/a1/Snail-WA_edit02.jpg
http://etc.usf.edu/clipart/25100/25194/shell_25194_lg.gif
PlanospiralUncoiled
Whorl
http://www.palaeos.com/Invertebrates/Molluscs/Gastropoda/Images/Bellerophon.jpg
http://palaeo.gly.bris.ac.uk/Palaeofiles/Fossilgroups/gastropo/Diagrams/tort.gif
Torsion
http://www.weichtiere.at/images/weichtiere/schnecken/torsion.gif
180◦ counterclockwise rotation of visceral mass
Anus position
Gill position
WHY?
Torsion - WHY?
Larval theory – allows foot to be brought up into shell
Torsion - WHY?
Adult theory – allows for better
ventilation of mantle cavity and gills
Places osphridium anteriorly
May help increase efficiency of creeping with a coiled shell
Problem from torsion
Sanitation Slits or holes to
accommodate waste
Unidirectional flow of water
http://eebweb.arizona.edu/collections/Fishes/Invertebrate%20Slide%20Photos/Invertebrate%20Photos/Abalone%201.jpg
http://www.mesa.edu.au/friends/seashores/images/limpet_under.gif
Class Gastropoda - Diversity
Subclass – Prosobranchia Order Archeogastropoda Order Mesogastropoda Order Neogastropoda
Subclass Ophistobranchia Subclass Pulmonata
Molecular evidence indicates that these classifications are no longer valid!
Subclass Prosobranchia -
Usually with a spirally coiled shell (whorl)
Mantle cavity anterior Osphridium (not shown) Gills Anus Nephridiopore (not
shown)
http://snugglynoodles.com/images/haeckel/Haeckel_Prosobranchia.jpghttp://www.nmfs.noaa.gov/pr/images/invertebrates/blackabalone_anatomy.jpg
Order Archeogastropoda
Primative Herbivores
Radula has numerous teeth in transverse rows
1-2 bipectinate gills Mantle cavity without siphon Sexes separate
Order Archeogastropoda
Abalone Keyhole
limpets Limpets*
http://www.anth.ucsb.edu/faculty/glassow/RAMP/abalone.jpghttp://www.marlin.ac.uk/imgs/Species/Mollusca/o_diogra.jpg
* Order Patellogastropoda
http://www.marietta.edu/~biol/biomes/images/shores/shield_limpet_6150.jpg
Order Mesogastropoda
http://www.maier-kern.com/wordpress/wp-content/uploads/2006/02/DSC02058.JPG
Vermetidae
Hydrobia
Turritellidae
http://elrinconmarinosgasteropodos.iespana.es/Fotos%20coleccion/Cerithidae.jpg
Cerithidae
http://www.shellmuseum.org/Shells2/alatus2.jpg
Strombidae
Janthinidae
http://elrinconmarinosgasteropodos.iespana.es/Fotos%20coleccion/Janthinidae.jpg
http://www.seashell-collector.com/beginners/CAPULIDAE.jpg
Capulidaehttp://www.seashell-collector.com/beginners/CALYPTRAEIDAE.jpg
Calyptraeidae
http://www.eumed.net/malakos/Images/Carinaria_mediterranea.jpg
Carinaridaehttp://www.timespub.tc/fileadmin/user_upload/featured/Summer2004/Shell%2028.jpg
Naticidae
http://www.seashell-collector.com/beginners/CYPRAEIDAE.jpg
Cypraeidae
http://www.seashell-collector.com/beginners/OLIVIDAE.jpg
Olividae
http://www.dkimages.com/discover/previews/965/50007882.JPG
Tonnidae
http://seashellplace.com/catalog/images/BullmouthCameoHelmet.jpg
Cassidae
http://www.seashell-collector.com/beginners/FICIDAE.jpg
Order Mesogastropoda
Operculum present Radula with seven
teeth/row Only left gill –
unipectinate One atrium One nephridium
http://oceanica.cofc.edu/shellguide/pics/univalve.gif
Order Neogastropoda
Order Neogastropoda
Entirely marine Radula with 3 or fewer
teeth per row One gill One atrium One nephridim
Order Neogastropoda
Mollusca – Order Neogastropoda Cone snail