PHYLUM ROTIFERA - ReproductionSupplementary Figure Not Shown in Lecture

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 (?)

Protozoa

Ancestral Metazoan

Cnidarians

Sponges

Flatworms

NemerteansNematodes

GastrotrichsRotifers

Arthropods

Annelids

MollusksBryozoans

Brachiopods

Chordates

Echinoderms

Hemichordates

INTRODUCTION

ACOELOMATEACOELOMATEPSEUDOCOELOMATEPSEUDOCOELOMATE

COELOMATECOELOMATE

% 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%)

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

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

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]

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

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

plate

plates

BODY FORM AND FUNCTIONPolyplacophora

plates

BODY FORM AND FUNCTIONPolyplacophora

Gastropoda

BODY FORM AND FUNCTIONBivalvia

BODY FORM AND FUNCTIONBivalvia

Cephalopoda

BODY FORM AND FUNCTION

Odontophore cartilage-like supportive structure Radula firm ribbon of teeth arranged in rows Buccal Mass

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

BODY FORM AND FUNCTIONdirection of esophagus

protractor muscles

retractor muscles

http://www.youtube.com/watch?v=cEMK3VN8pW8

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

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