animals - lecture 9 - october 8 2013 - post-2.pdf
DESCRIPTION
york u lecture 9 animalsTRANSCRIPT
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PHYLUM ROTIFERA - ReproductionSupplementary Figure Not Shown in Lecture
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OUTLINEPhylum Mollusca
Animal Diversity 6th Ed.Chapter 10, Pages 186 - 2125th Ed. Chapter 10, Pages 178 - 203
1. Introduction
2. Body Form and Structure
3. Reproduction & Development
- simple body plan- buccal mass and radula- shell structure and formation
4. Colour Change in Cephalopods (?)
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Protozoa
Ancestral Metazoan
Cnidarians
Sponges
Flatworms
NemerteansNematodes
GastrotrichsRotifers
Arthropods
Annelids
MollusksBryozoans
Brachiopods
Chordates
Echinoderms
Hemichordates
INTRODUCTION
ACOELOMATEACOELOMATEPSEUDOCOELOMATEPSEUDOCOELOMATE
COELOMATECOELOMATE
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% representation of extant molluscan
classesGastropoda
INTRODUCTION
Mollusca represented by approx. 93 000 species
*Monoplacophora (0.03%)*Aplacophora (0.40%)
Scaphopoda (1.0%)Polyplacophora (1.0%)
Cephalopoda (1.0%)
Bivalvia (21.5%)
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INTRODUCTIONMollusca are characteristically diverse
Size range: 1 mm 18 m (~ 59 ft)
Habitat range: 7000 m above sea level to abyssal depths
Locomotion: sessile, sluggish swift
Diet: herbivores, detritovores, filter feeders & predatory carnivores
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INTRODUCTION
Phylum MolluscaClass
aquatic/semi-terrestrial
Polyplacophora BivalviaGastropoda Cephalopoda
aquatic aquatic
7-8 dorsal plates
coiled orabsent
reduced, present or
absent
Form
Habitat
2 lateral plates
1. Shell
aquatic/terrestrial/semi-terrestrial
2. Foot modified to form arms
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INTRODUCTION
A typical mollusc is a hypothetical mollusc
Defining characteristics:
1. Mantle specialized tissue formed by dorsal epitheliumSecretes shell(s)
2. Radula tongue-like organ with teeth used for feeding*
3. Foot ventral body wall muscles developed for locomotionor clinging
*radula lost in bivalvia
What is a typical mollusc?
[Head-Foot]
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BODY FORM AND FUNCTION
Foot
Mantle
Shell Visceral mass
Mantle cavity
Simplest body plan consists of:1. Foot OR head-foot portion2. Visceral mass portion3. Shell
Radula in buccal mass
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BODY FORM AND FUNCTION
Foot
Mantle
Shell
Mantle cavity
Simplest body plan consists of:Respiratory organs: ctenidia ciliated molluscan gills
housed in mantle cavityCiliary function:
1. Provide continuous watercurrent into/out of cavity
- respiratory
- waste elimination
- sensory detection- gamete dispersal
- prevent fouling
2. Modified for filter feedingCtenidia
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plate
plates
BODY FORM AND FUNCTIONPolyplacophora
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plates
BODY FORM AND FUNCTIONPolyplacophora
Gastropoda
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BODY FORM AND FUNCTIONBivalvia
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BODY FORM AND FUNCTIONBivalvia
Cephalopoda
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BODY FORM AND FUNCTION
Odontophore cartilage-like supportive structure Radula firm ribbon of teeth arranged in rows Buccal Mass
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BODY FORM AND FUNCTION
Odontophore cartilage-like supportive structure
protractor muscles
retractor musclesradular sac
odontophore
radula teeth
Radula firm ribbon of teeth arranged in rows Buccal Mass
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BODY FORM AND FUNCTIONdirection of esophagus
protractor muscles
retractor muscles
http://www.youtube.com/watch?v=cEMK3VN8pW8
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BODY FORM AND FUNCTIONMolluscan shell(s) made up of 3 regions:
1. Periostracum thin, outer layer composedof an organic substance, conchiolin
2. Prismatic layer middle layer composedof calcium carbonate and protein matrix
3. Nacreous layer inner calcareous layercomposed of nacre (CaCO3 in protein matrix)
Secretion: mantle edge at shell margin
Secretion: mantle edge at shell margin
Secretion: mantle surface
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BODY FORM AND FUNCTIONPearl production a by-product of defense
Nacre forming materials secretedinto extrapallial spaceextrapallial
space
Mantle attached to shell along the inner shell edge (pallial line)
- foreign object (e.g. sand grain) or parasitebetween mantle and shell is enclosed in nacre
- if object is enfolded by mantle, concentriccircles of nacre form a pearl
- more commonly, object remains attached tonacreous layer of shell