Molluscs in General
Class Gastropoda
Class Bivalvia
Class Cephalapoda
OTHER CLASSES

100
Tissue organization?

Symmetry?


Coelom?

Triploblastic

Bilateral


Coelomate (small in pericardial cavity)

100
What are these and where do they live?
Snails, limpets, slugs...etc.

Live marine, freshwater, terrestrial

100
What are these?
Clams, mussels...etc.
100
What are they?
Octopussies
100
What are the polyplacophora and what are their main traits?
They are chitons (lil pill bug lookin things that live on hard substrates in shallow water)

- reduced head

- flat foot

- 8 dorsal valves

- ladder-like nervous system

- development external w/ trochophore larval stage

- feed by rasping algae on substrate

200
Describe general body form
Two body sections:

1. Head-foot: body region that has head + responsible for locomotion, sensory stuff, retracting visceral mass into shell + attachment w/ foot

2. Visceral mass: region that has all the organs

200
What is torsion?
Unique to gastropoda, when the visceral mass, mantle + mantle cavity twist 180 degrees counterclockwise during developmental phase.


Results in: anterior opening of mantle cavity and digestive "U" + it poops at a 90 degree angle

200
General Body Form:
Two halves called "valves", that are connected at the dorsal region (where the umbo is anteriorly located).

Anterior = apex


Have adductor muscles that keep the valves closed

200
What makes them unique from the other molluscs?
- most complex?
- anterior of foot = tentacles/arms for prey catching, locomotion, attachment and sexy times

- foot associated w/ mantle cavity for jet propulsion

- cephalopod head in line w/ visceral mass

- mantle on whole body except tentacles + head

-closed circulatory sysstem

- no blind spots (EYES)

- has chromatophores for camouflage + impressing the ladies ;)

-large brain (predatory!)

200
Class Scaphopoda + traits
Tooth shells/tusk shells

- conical shell open on both ends

- apex is above substrate into water

- development external

- gas exchange across mantle folds

300
Circulatory system?
Open (pericardial cavity) (except in Cephalopoda)
300
Benefits of torsion.
1. head enters shell first (important bits, and operculum lid closes the foot)


2. clean water from front enters mantle cavity

3. snail more sensitive to direction it is going :)

300
How does their eating work?
Filter feeding life-styles.


Labial palps direct food towards the mouth.

Gills trap food in mantle cavity and brings them to food grooves. 

Mucoid string that's conveyer belt.

intestine = biocardial 

style contains digestive enzymes and spins to release them

300
What the shell is up w/ it?
In some, nautlius that it grows in and leaves behind, in some no shell, in squid = pen (chitinous structure around itself)


reduced or absent

300
Class Monoplacophora
- undivided, arched shell

- serially repeated gills

- deep-water

- foot-retractor muscles

400
What are traits unique to molluscs and what do they do?
Mantle: outer fleshy tissue that can secrete the shell (3 layers)


Mantle Cavity: space between the visceral mass and the mantle (gas exchange, waste removal, reproductive product release)

Radula: rasping, tongue-like structure in mouth of mollusc that uses chitinous minute teeth moving over a cartilaginous odontophore to scrape food

400
What do slugs (who don't have a mantle) use for defense?
Take nematocysts from cnidarian prey to ward off predators.
400
Reproduction
most dioecious (some monoecious)


- gametes expelled through exhalant opening (external fertilization)

- trochophore (veliger stages)

- unionids (freshwater mussel) brood veliger (glochidium larva)

400
How do they move?
Jet-propulsion!


Circular muscles contract (decrease vol in mantle cavity + close valves which forces water out of the small siphon)

Radial muscles bring water in to increase vol

Fins steer the ship!

400
Class Solenogaster + trait
HOT DIGGITY DOG!


- cylindrical marine

-lack shell

-pedal groove (walk)

- feed on cnidarian polyps

-monoecious

500
Relationships between them?

500 million years old (began right before cambrian, wild diversity check during cambrian)

Polyplacophoran:

8 shell - intermediate

large foot - seen first in these

"girdle" - remnant of cuticle

500
What body parts have they lost from ancestors and why?
Radula + head and because of filter-feeding lifestyle
500
Circulatory/nervous/reproductive systems?
Circulatory = closed


Nervous = complex, large brain capable of learning, with eyes w/ no blind spots

Reproductive = dioecious w/ gonads in dorsal of visceral mass, sperm packets inserted into female for external egg fertillization

500
Class Caudofoveata + traits
worm-like burrowers on deep sea floor


lack muscular foot + shell

M
e
n
u