BIO2231 - Mollusca I Flashcards

Question 1

Q

Describe

Lophotrochozoa

4 points.

Answer

A

aka " Spiralia

<ul><li>Molecular characteristics separate this group from Ecdysozoa </li><li>Spiral determinate cleavage (typical protostome) </li><li>Some phyla have a lophophore e.g. Bryozoa (discussed in upcoming </li><li>Some phyla in this group have trochophore larvae e.g Mollusca, Annelida</li></ul>

_{BIO2231 4aa}

Question 2

Q

Mollusca - list members.

Answer

A

<ul><li>Snails & slugs</li><li>Squid, cuttle fish & octopus</li><li>Clams, oysters etc.</li><li>Tusk shells</li><li>Chitons</li></ul>

_{BIO2231 4ab}

Question 3

Q

Phylum Mollusca - Main features

Answer

A

<ul> <li>Bilaterally symmetrical</li> <li>Triplobastic coelomates</li> <li>Trochophore larva</li> <li>Organ system level</li> <li>Marine, freshwater & terrestrial</li> <li>2ⁿᵈ largest phylum</li></ul>

_{BIO2231 4ac}

Question 4

Q

Describe

Hemocoel

Answer

A

Formed by fusion of blastocoel with bits of the coelom from embryo

_{BIO2231 4ad}

Question 5

Q

"Generalised mollusc" - Basic body plan

Body wall

Answer

A

Body wall: dorsally >> Mantle!

<ul> <li>Mantle cavity with gills (ctenidia) or lung</li> <li>Skirt (mantle edge)</li> <ul> <li>sensory</li> <li>secretory</li> </ul> <li>Shell</li></ul>

_{BIO2231 4ae}

Question 6

Q

What is the Periostracum?

Answer

A

Outer organic layer of the mollusc shell

_{BIO2231 4af}

Question 7

Q

What is the Prismatic Layer?

Answer

A

Middle CaCO₃ layer of the mollusc shell

_{BIO2231 4ag}

Question 8

Q

What is the Nacreous?

Answer

A

Inner mother of pearl layer of the mollusc shell.

_{BIO2231 4ah}

Question 9

Q

Describe

Mollusc Shell

Answer

A

<ul> <li>Material secreted by mantle</li> <li>Mantle lines the shell</li> <li>Three layers</li> <ul> <li>Periostracum (organic)</li> <li>Prismatic (CaCO₃)</li> <li>Nacreous (mother of pearl)</li> </ul></ul>

<ul> <li>Originally probably dome shaped</li> <li>Protects visceral mass </li> <li>Many modified forms</li></ul>

_{BIO2231 4ai}

Question 10

Q

Describe

What are Ctenidia?

Answer

A

A comblike structure, especially a respiratory organ or gill in a mollusc, consisting of an axis with a row of projecting filaments

_{BIO2231 4aj}

Question 11

Q

List

Respiratory structures

5 points.

Answer

A

<ul> <li>Mantle cavity wall</li> <li>Ctenidia (gills) w. many modifications</li> <ul> <li>Blood supplied from heart, with 2 arteries going into gills</li> </ul> <li>"Lungs" in pulmonate snails (lost gills)</li> <li>"secondary gills" (lost ctenidia , developed modified gills)</li></ul>

_{BIO2231 4ak}

Question 12

Q

"Generalised mollusc" - Basic body plan

Coelom

Answer

A

Coelom >> Reduced!

<ul><li>Around heart (& kidney) </li><li>Hemocoel (open circulatory system) with sinusses (cavity or space in tissues)</li></ul>

_{BIO2231 4al}

Question 13

Q

"Generalised mollusc" - Basic body plan

Excretory system

Answer

A

<ul><li>Blood from heart flows through heart wall, becoming pericardial fluid.</li><li>Fluid enters nephridium via nephrostome and is filtered.</li><li>Passed out of body through mantle cavity or nephorostome</li></ul>

_{BIO2231 4am}

Question 14

Q

What is a Metanephridia?

Answer

A

Type of nephridium , inner end opens into coloem

_{BIO2231 4an}

Question 15

Q

What is Pericardial fluid?

Answer

A

Fluid around heart

_{BIO2231 4ao}

Question 16

Q

"Generalised mollusc" - Basic body plan

Feeding

3 points.

Answer

A

Feeding >> Radula!

<ul><li>Digestive system complex </li><li>Anus in mantle cavity </li><li>Diverse</li></ul>

_{BIO2231 4ap}

Question 17

Q

Definition

Radula (Mollusc specific)

9 points.

Answer

A

<ul> <li>Tongue like with many teeth</li> <li>Originally rasping structure</li> <li>Moves over supporting odontophore "</li> <li>Transports food inside (conveyor)</li> <li>Specialised in some species</li> <ul> <li>E.g. hunters:</li> <ul> <li>radula drills hole in prey’s shell</li> <li>proboscis inserted through hole and tissue extracted</li> <li>Cone shells have toxic radula</li> </ul> </ul></ul>

_{BIO2231 4aq}

Question 18

Q

"Generalised mollusc" - Basic body plan

Head-Foot

4 points.

Answer

A

<ul><li>Ventral muscular foot for locomotion </li><li>Often modified </li><li>Head poorly defined </li><li>Retractable</li></ul>

_{BIO2231 4ar}

Question 19

Q

"Generalised mollusc" - Basic body plan

Nervous system

3 points.

Answer

A

<ul><li>Ring around oesophagus </li><li>Nerve cords </li><li>Ganglia</li></ul>

_{BIO2231 4as}

Question 20

Q

Describe

Class Polyplacophora

5 points.

Answer

A

<ul> <li>Dorsoventrally flattened</li> <li>Dorsal plates, extended mantle</li> <li>Marine, not very mobile</li> <li>Many gills in pallial groove</li> <li>Radula scrapes algae</li></ul>

<div>Southern Australia has highest diversity in the world</div>

_{BIO2231 4at}

Question 21

Q

Describe

Class Gastropoda

7 points.

Answer

A

<ul> <li>Generally slow moving</li> <li>Marine, terrestrial, freshwater</li></ul>

<div>Mantle</div>

<ul> <li>mantle tissue secretes shell</li> <li>mantle cavity contains gills</li></ul>

<div>Visceral mass (hump)</div>

<ul> <li>internal organs</li></ul>

<ul> <li>head with sensory structures</li> <li>muscular foot for locomotion</li></ul>

_{BIO2231 4au}

Question 22

Q

Describe

Class Gastropoda

7 points.

Answer

A

<ul> <li>Largest most diverse class</li> <ul> <li>Snails, limpets, periwincles , abalones, sea hairs, nudibranchs etc</li> </ul> <li>Shells for protection (univalve, coiled)</li> <ul> <li>Many shapes evolved, or sometimes lost</li> </ul> <li>Planospiral >> conispiral</li> <li>Torsion of visceral mass & mantle cavity</li> <li>Trochophore larva >> Veliger larva</li></ul>

_{BIO2231 4av}

Question 23

Q

Describe

Gastropod evolution - coiling

<div>7 points.</div>

Answer

A

<ul> <li>Early gastropods were bilaterally symmetrical</li> <li>Planospiral shell not compact</li> <li>Conispiral shells more compact but unbalanced</li> <li>Better weight distribution achieved by moving shell</li> <ul> <li>upwards and back</li> <li>and to the right</li> </ul> <li>BUT resulted in compression of right side of mantle cavity, impairing organ function, so</li> <li>Bilateral asymmetry of some organs (right side lost)</li> <li>WAIT, let's go back again</li> <ul> <li>Detorsion (partial or full) </li> <li>Planospiral shells</li> </ul></ul>

_{BIO2231 4aw}

Question 24

Q

Gastropod respiration

Answer

A

<div>Most marine gstropods: have lost one gill</div>

<div>Terrestrial pulmonate snails: A “lung” through The loss of both gills and using mantle cavity</div>

_{BIO2231 4ax}

Question 25

Q

Class Gastropoda - Prosobranchs

3 points.

Answer

A

<ul><li>Most gastropods </li><li>Mainly marine and some freshwater </li><li>Respire with leaf like ctenidia</li></ul>

_{BIO2231 4ay}

Question 26

Q

Class Gastropoda - Opistobranchs

5 points.

Answer

A

<ul><li>Mostly marine, few freshwater </li><li>Sea hares, sea slugs and nudibranchs </li><li>Show partial or full detorsion </li><li>Shell and mantle cavity reduced or absent </li><li>Ctenidia replaced by folded external gills in some species</li></ul>

_{BIO2231 4az}

Question 27

Q

Class Gastropoda - Pulmonates

4 points.

Answer

A

<ul><li>Garden snails, slugs </li><li>Mainly terrestrial but NOT ALL </li><li>No ctenidia </li><li>Vascularised mantle cavity modified as lung for "breathing" air</li></ul>

_{BIO2231 4ba}

Brainscape's Knowledge GenomeTM

BIO2231 - Mollusca I Flashcards

Brainscape's Knowledge Genome^TM