I. Phylum Mollusca
A. Class Gastropoda (last lecture)
B. Class Polyplacophora (chitons)
1. Body plan
2. Feeding
3. Reproduction
C. Class Bivaliva (clams, etc)
1. Body plan
2. Feeding
3. Lifestyle variations
4. Reproduction
D. Class Cephalopoda
1. Body Plan
2. Protection
3. Nervous system/Behavior
4. Feeding
5. Reproduction
Bio 125 lecture #9 (2/16/17)
Phylum Mollusca - Class Polyplacophora
(Chitons)
Reminder:
Lab field trip next week to
Carpinteria Salt Marsh (directions on
p1 of that lab)
Do NOT be late – we enter thru a
locked gate!
Phylum Mollusca: Class Polyplacophora (Chitons)
Feeding:Mainly herbivores of microalgae on rocks
Phylum Mollusca: Class Polyplacophora (Chitons)
Reproduction
• Separate sexes
• Broadcast spawn (gonopore) – external
fertilization
•external fertilization
•Radula hardened with magnetite
Exception: Carnivore Placiphorella velata
• Trocophore
larvae
Derek Gerstmann, U W. Australia
Phylum Mollusca: Class Bivalvia
(clams, mussels, oysters)
Bivalves are filter feeders
Using:
Cilia, siphons, gills, palps
palps
1
Phylum Mollusca: Class Bivalvia
Lifestyle Variation
Phylum Mollusca: Class Bivalvia
Lifestyle Variation
1. Burrowers
• Some clams – enlarged foot
for burrowing/digging
• mantle may be fused &
elongated into 2 siphons
2. Boring bivalves
• Shipworm
•
Shipworm
–
Burrows
with shell
Siphons
project out
of wood
Phylum Mollusca: Class Bivalvia
Lifestyle Variation
3. Sessile (attached to substrate surface)
• foot reduced or absent (scallops, oysters)
• attach either by 1 valve (scallops, oysters)
or byssal threads (mussels)
• Date mussels
• Rock-boring piddock
Phylum Mollusca: Class Bivalvia
Lifestyle Variation
4. Free-living
(swimming scallops
& some clams)
https://www.youtube.com/wat
ch?v=_2iXHBuSIJY
• reduced foot
http://www.arkive.org/commonmussel/mytilus-edulis/video-03.html
http://www.npr.org/templates/story/story.php?storyId=124319594
Phylum Mollusca:
Class Bivalvia
Reproduction
• Separate sexes
• Broadcast spawn
• veliger with 2 valves
• No torsion
Phylum Mollusca
Class Cephalopoda
Cuttlefish
“head-foot”
Octopus
Squid
Chambered Nautilus
2
Phylum Mollusca, Class Cephalopoda
Basic Body form
a. Shell/Structural Support
1. Octopus: none
2. Squid: pen
Phylum Mollusca, Class Cephalopoda
Basic Body form
a. Shell/Structural Support
4. Nautilus:
External shell
Phylum Mollusca, Class Cephalopoda
Basic Body form
a. Shell/Structural Support
3. Cuttlefish: cuttlebone (also for buoyancy)
Phylum Mollusca, Class Cephalopoda
Basic Body form
b. foot modified into arms & tentacles
- with suckers (except nautilus)
Arms – suckers
along whole length
Tentacles –
suckers only at
tips
Phylum Mollusca, Class Cephalopoda
Basic Body form
c. distinct head, near foot
Phylum Mollusca, Class Cephalopoda
Basic Body form
d. body protected by thick, muscular
mantle
Large, complex
eyes
Modified into 2
lateral fins in
squid
Mouth surrounded by arms, tentacles
3
Phylum Mollusca, Class Cephalopoda
Basic Body form
e. mantle cavity behind head
Encloses 2-4 gills, NO cilia
Phylum Mollusca, Class Cephalopoda
Basic Body form
f. mantle rolled into siphons
3 functions of
siphon:
1.Breathing
(self & eggs)
2. Swimming
3. Defense
Siphon
Phylum Mollusca, Class Cephalopoda
Protection
Phylum Mollusca, Class Cephalopoda
Nervous/sensory system & Behavior
1. Most complex invertebrate nervous system
1.Ink
2. Camouflage
2. Single, large brain
3. Giant nerve fibers
(rapid impulses)
4. High learning
capacity
5. Elaborate
disguises
http://www.youtube.com/watch?v=RUN6c5yWJhQ&feature=fvw
http://www.youtube.com/watch?v=PmDTtkZlMwM
Phylum Mollusca, Class Cephalopoda
Feeding:
• Mouth between arms
• Chitinous beaks
Phylum Mollusca, Class Cephalopoda
Feeding
Poison (some)
Radula (inside beak)
Promachoteuthis sulcus
http://www.cnn.com/videos/world/2015/02/24/lkl-fosteroctopus-crab-battle.cnn/video/playlists/trending-video/
4
Phylum Mollusca: Class Cephalopoda
Reproduction
• Separate sexes
• Internal fertilization
Hectocotylus
– modified arm (males)
Phylum Mollusca, Class Cephalopoda
Reproduction
• Lay eggs
Squid (open)
Octopus
Lecture #12(den)
(3/1/16): Phylum Mollusca II
Photos: RL Caldwell (UCB)
Phylum Mollusca, Class Cephalopoda
Reproduction
• Direct development
(no larval stage)
Lecture #12 (3/1/16): Phylum Mollusca II
1. How many shells do members of Class Polyplacophora
(chitons) have?
2. What feature makes the radula of chitons so good for
grazing microalgae off hard rocks?
3. What type of reproduction
chitons use?
• Adultdo
usually
dies
4. Class Bivalvia differs from other molluscs in that they
(reproduce 1x/life)
lack a _____ and a _________
5. How do bivalves eat? What part of their body do they
use for feeding?
6. List the 4 different lifestyles of bivalves and provide
one adaptation for living in each different
environment.
7. Class Cephalopoda : Describe the shell & foot
modification in each of the following: octopus, squid,
cuttlefish, nautilus.
8. What part of the body forms siphons in Mollusca?
9. List 3 possible functions of the siphon in Cephalopods.
10.How does the mantle of Cephalopods differ from
that of other classes?
11.Cephalopods are unusual among Molluscs in that
they do NOT have cilia in their mantle cavity to help
circulate water – so how do they get water to
circulate?
12.Chromatophores are specialized skin cells in
cephalopods that are used for protection. Describe
how they are structured and how they work.
1. How many shells do members of Class
Polyplacophora (chitons) have?
2. What feature makes the radula of chitons so good
for grazing microalgae off hard rocks?
3. What type of reproduction do chitons use?
4. Class Bivalvia differs from other molluscs in that
they lack a _____ and a _________
5.
How do
eat?Study
What
part of their body do
Lecture
#9bivalves
(2/15/17):
Questions
forshells
feeding?
1.they
Howuse
many
do members of Class
6. List
the 4 different
lifestyles
of bivalves and
Polyplacophora
(chitons)
have?
provide
one
adaptation
for
living
each different
2. What feature makes the radula ofinchitons
so good
environment.
for grazing microalgae off hard rocks?
7.
: Describe
shell use?
& foot
3.Class
WhatCephalopoda
type of reproduction
dothe
chitons
each of
theother
following:
octopus,
4.modification
Class Bivalviaindiffers
from
molluscs
in that
squid,
cuttlefish,
they lack
a _____nautilus.
and a _________
8.
part
of the body
siphons
in Mollusca?
5.What
How do
bivalves
eat? forms
What part
of their
body do
9. List
possible
functions of the siphon in
they3 use
for feeding?
6.Cephalopods.
List the 4 different lifestyles of bivalves and
10.How
does
the
mantle offor
Cephalopods
differ
from
provide
one
adaptation
living in each
different
that
of other classes?
environment.
11.Cephalopods are unusual among Molluscs in that
they do NOT have cilia in their mantle cavity to
help circulate water – so how do they get water to
circulate?
12.Chromatophores are specialized skin cells in
cephalopods that are used for protection.
Describe how they are structured and how they
work.
13.Besides color change, what is one other way that
most cephalopods can defend themselves?
14.Octopi have more complex behavior than other
molluscs. Explain why this is so.
15.How does the mouth of Cephalopods differ from
other Molluscs?
16.What type of reproduction do Cephalopods have?
17.Cephalopods have “direct development” – what
does that mean?
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