Mollusca

Paul Ko

Andy Zhao

Michael Chiu

Period 5http://www.fossilmuseum.net/Tree_of_Life/PhylumMollusca/images/Nautilus-wpd.jpg

4 Major Classes:•Polyplacophora•Bivalvia•Gastropoda•Cephalopoda

http://upload.wikimedia.org/wikipedia/commons/a/a4/Ab_mollusca_01.jpg

Class Polyplacophora

http://www.wallawalla.edu/academics/departments/biology/rosario/inverts/Mollusca/Polyplacophora/TonicellaLineataDLC1991.jpg

• Chiton• Marine• Shell with Eight Plates• Foot used for locomotion• Radula• No head

Bivalvia

• Clams and oysters• Sedentary or sessile filter-feeding• Marine and Freshwater or Terrestrial•Head reduced•Paired Gills•No radula

http://www.korseby.net/outer/fauna/mollusca/bivalvia.jpeg

http://upload.wikimedia.org/wikipedia/en/4/47/Banana_slug_closeup.jpg

Gastropoda

• Aquatic and terrestrial snails and slugs•Marine, Freewater/terrestrial•Usually has a shell•Foot for locomotion•Radula

http://static.open.salon.com/files/octopus1244124973.jpg

Cephalopoda

• Predatory cuttlefish, squids and octopi.•Marine•Head surrounded by tentacles•Tentacles usually have suckers•External, internal or absent Shell•Mouth with or without radula

Body Cavities

o The body cavities in Mollusca are called mantle cavities (coelom), which are:

http://www.southtexascollege.edu/nilsson/4_GB_Lecture_figs_f/4_GB_23_AnimaliaInvert_Fig_f/BodyCavity_Coelom_29A.GIF

o Water-filled cavities that house the gills, anus, and excretory pores. o There are also blood cavities known as hemocoel which store blood in open-circulatory mollusca.

Body Symmetry

• All mollusca have bilateral symmetry meaning…

• The organism can be cut in half with the two sides looking more or less exactly the same.

• Ex:

http://chemistry.csudh.edu/faculty/jim/cozaugo4-600/octopus.jpg

http://infusion.allconet.org/webquest/PhylumMollusca.html

Nervous System

http://media.photobucket.com/image/cuttlefish/Nephlabobo/ComCuttlefish9.jpg

http://animaldiversity.ummz.umich.edu/site/resources/biodidac/bivanerv.jpg/medium.jpg

•Relatively complex nervous system, varies from species to species.

•All Mollusca have tentacles that have sensors to detect chemicals, vibrations and touch.

•Mollusca have ganglia, a sort of brain-like organ.

Circulatory System• Other than cephalopods, all

Mollusca have an open circulatory system

• These cavities are known as hemocoel, and in mollusks, it has replaced the coelem.

• Cephalopods need a closed-circulatory system because their activities require more energy.

http://www.esu.edu/~milewski/intro_biol_two/lab__11_mollusca/images/bivalve_circulatory.jpg

Digestive System• Radula to scrape up food• Digestive tract is

complete and ciliated• Includes mouth, anus

and complex stomach• Food is taken up by the

digestive glands arising from the stomach, where it is passed into the blood

http://kentsimmons.uwinnipeg.ca/16cm05/1116/33-16-MolluskBodyPlan-L.gif

Excretory System

• Waste is in solid form so it prevents the fouling of water over gills

• Excretory functions are regulated by a pair of nephridia and tubular structures

• Collect fluids from coleom and exchanges salts and substances with body tissues during excretion

http://awakeningwomen.files.wordpress.com/2009/09/dumbo-octopus.jpg

Locomotion/Musculature

• Foot comprised of 3 main body parts– Viceral mass: contains interal organs– Mantle: fold of tissue over visceral mass, includes shell (if

present– Mantle Cavity: houses gills and anus and excretory skills

• Herbivores are commonly gliders, move on muscular contraction

• Carnivores, more advanced locomotion– Cephalopods – Jet Propulsion– Cuttlefish/Sea Hares – Undulating later fins– Bivalves – Foot for burrowing

http://www.ck12.org/ck12/images?id=113229

Skeletal System

N/A

BUT………………………….

They have shells madeof calcium carbonate

http://www.naturfoto-cz.de/photos/others/roman-snail-21973.jpg

Sensory Structures/Features

• Some mollusks have large complex eyes (notably the cephalopods)

• Squids can locate and capture transparent prey with specialized polarization vision.

http://www.news.wisc.edu/newsphotos/images/Hawaiian_bobtail_squid04.jpg

Reproduction• Sexual Reproduction

• External Fertilization: Sperm cell is united with egg cell away from the parents.

• Trochophore = Larvae

• Internal Fertilization

Example: Land snails are hermaphrodites. They have a pouch for holding the sperm of the mate.

http://www.dlia.org/atbi/species/Animalia/Mollusca/Gastropoda/images/reproduction/mesomphix_inornaus_DD300.jpg

http://www.vattenkikaren.gu.se/fakta/arter/mollusca/bivalvia/ostredul/ostrliv.gif

http://www.bobtherieau.com/images/blog/claM.jpghttp://www.nicertutor.com/doc/class/bio1903/Locked/media/

ch32/32_13Trochophore.jpg

Gas Exchange• Generally takes place in the true gills (ctenidia)

• Absorbs the Oxygen from water and diffuses Carbon Dioxide into the water.

www.biol.wwu.edu/donovan/biol460/12mollusca.ppt

http://kentsimmons.uwinnipeg.ca/16cm05/1116/33-16-MolluskBodyPlan-L.gif

Unique Features• Mantle: Encloses mantle cavity, which

circulates oxygen and water.

• Radula: The mouth, with teeth bent inwards. Ctenidia

Calcium Carbonate Shells

http://s3.amazonaws.com/wootdesigncontestentries/Shigwarm/Giant_Squid_vs._Jet_Fighter-f1e6n4-d.jpghttp://www.bio.miami.edu/dana/pix/ham.jpg

QUIZ QUESTIONS!!1. Which of the following phyla do not have symmetry? a. Mollusca b. Porifera c. Echinodermata

2. Which of the following classes of Mollusca need a closed circulatory system?

a. Cephalopoda b. Bivalvia c. Gastropoda d. Polyplacophora

http://en.wikipedia.org/wiki/File:Tonicella-lineata.jpg

Quiz Questions (Cont.)3. Excretory functions are regulated by…

a. Nephridia b. Tubular structures c. Both d. Neither

4. Land Snails reproduce…a. Through internal fertilization b. Through external fertilizationc. Sexuallyd. Asexually

5. Why don't they serve escargots at a McDonald's restaurants?

http://biology.unm.edu/ccouncil/Biology_203/Images/Protostomes/squid.jpg

Answers

1. b

2. a

3. d

4. a

5. They only serve fast food

Thank You

http://lair2000.net/Mermaids_Retreat/Research/kraken.jpg