Midterm 2

Question 1

Mollusc key characteristics

Answer 1

• Visceral Mass

* Head- foot

Question 2

The Head

Answer 2

• Feeding
  
  • Sense organs
  • Brain, eyespots-to-eyes, tentacles

Question 3

The Radula

Answer 3

• Part of the Head-Foot
  
  • Chitinous ribbon of teeth
  • NOT in any Bivalve
  • Odontophore cartilage holds teeth
  • Muscles move it in and out
  • Muscles to move odontophore and muscles to move radula

Question 4

The Foot

Answer 4

Locomotion, attachment

Ventral

Question 5

• Visceral Mass

Answer 5

• Internal organs
  
  • Digestive, excretory, reproductive and respiratory
    contains mantle and mantel cavity

Question 6

Mantle

Answer 6

• the “skin”
  * Can have muscles, or chemoreceptors, etc
  * Makes the shell

Question 7

• Mantle Cavity

Answer 7

open to “world”

* Excretion (metabolic and digestive), respiration, reproduction

Question 8

• Periostracum

Answer 8

• Outer organic layer (resistant protein conchiolin)

Question 9

• Prismatic layer

Answer 9

• Calcium carbonate stacks

Question 10

• Nacre

Answer 10

• Continuously thickens
  
  • Calcium carbonate + protein sheets
    Pearls

Question 11

Mantel layers

Answer 11

Nacre
Prismatic layer
Periostracum

Question 12

Reproductive System of Molluscs

Answer 12

• Never asexual
• Diocieous or monoecious
• Trochophore larvae in most
• Veliger larvae common
  
  • Aquatic Bivalves and Gastropods
• Some have direct development (no larvae)

Question 13

The Aplacophorans

Answer 13

• Contains classes Caudofoveata and Solenogastres
• Wormlike and shell-less
• Calcareous scales/spicules
• Marine detrital/microorganism consumers – burrowers!

Question 14

Class Monoplacophora

Answer 14

• Means one plate
• Thought to be extinct until 1952!
• Round shell, large foot
• Serial repetition of body parts
• Gills, nerves, gonads, nephridia…

Question 15

Class Polyplacophora

Answer 15

• Means many plates” – the chitons
• 8 moveable plates
• Mantle girdle around outside
• Intertidal rocky areas
• Serial repetition seen

Question 16

Class Scaphopoda

Answer 16

• Tusk shells/tooth shells
• Sedentary
• Tubular shell (open at both ends)
• Tentacular foot for burrowing and food capture
• A lot of diffusion in mantle cavity
  
  • No heart, no gills..

Question 17

Class Gastropoda

Answer 17

• Means stomach foot
• Most taxonomic rich (diverse) class – 60,000+
• Snails, periwinkles, limpets, sea slugs, slugs
• Marine, freshwater, terrestrial
• Coiled shell, domed shell, no shell
• 3 Main groups of Gastropods

Question 18

• Prosobranchia

Answer 18

• Most marine snails (periwinkles, limpets, conchs…)

Gastropods

Question 19

• Opisthobranchia

Answer 19

Gastropods

* (mostly) marine shell-less forms (nudibranchs, sea slugs...)
* cerrata

Question 20

• Pulmonata

Answer 20

Gastropods

* Most land and freshwater snails and slugs (mantle cavity into lung)

Question 21

Torsion

Answer 21

180 degree rotation of the mantle/mantle cavity, internal

Question 22

Coiling

Answer 22

whorling of the shell

Question 23

• Feeding Gastropods

Answer 23

all feed with some adaptation of the radula

Question 24

Gastropods reproduction

Answer 24

• Simultaneous hermaphrodites * Eversible penises and simultaneous sperm transfer
• Love Darts and Slug Orgies

Question 25

Class Bivalvia

Answer 25

• Laterally compressed shells
• Hinged dorsally; gape open ventrally
• Means two valve
• No head, no radula
• Bivalve locomotion
  
  • Foot to burrow (clams)
  • Adductor muscles to swim (scallops)
  • Some sessile
    
    • Byssal threads (mussels)
    • Cemented (oysters)

Question 26

Class Cephalopoda

Answer 26

* Means head-foot
predators  
* Exclusively marine 
    * Most have 1 pair of gills 
8 arms (2 tentacles for squid and cuttlefish)
    * Closed circulatory system
    * Incredible nervous system

Question 27

Chromatophores

Answer 27

Cephalopoda. Camouflage cells 4 types

Question 28

Cephalopoda Reproduction

Answer 28

• Dioecious
  
  • With some amazing mating rituals!
  • Copulation
  • Direct development (no larvae)
  • All but a couple species die

Question 29

Conchiolin

Answer 29

found in outermost layer of mantel shell (Prperiostracum)