Lab 5 - Mollusca Flashcards
what does HAM stand for?
hypothetical ancestral mollusc
Polyplacophora has (1)
chitons
Bivalvia has (2)
clams and mussels
Cephalopoda has (4)
octopus, squid, cuttlefish, and nautilus
Gastropoda has (2)
snails and slugs
Scaphopoda has (1)
tusk/tooth shells
four body regions of HAM
head, foot, visceral mass, and mantle
HAM: head
contains sensory organs and muscles
HAM: foot
a muscular structure used for locomotion (usually)
HAM: visceral mass
all the inners including digestive, reproductive, and circulatory organs
HAM: mantle (3)
epidermal layer that covers all of the visceral mass, delimits the mantle cavity, and it also secretes a shell in species that have one
Mollusks are an excellent example of _____ _____
adaptive radiation
Mollusca: organization level
organ level
Mollusca: development (3)
triploblastic, protostomes, eucoelomates
Mollusca: symmetry
bilateral
Mollusca: digestive
complete gut
Mollusca: support
CaCO2 shell secreted by mantle
Mollusca: excretion
via metanephridia
Mollusca: circulation
open circulatory system
what is the only class of Mollusca that has a closed circulatory system?
Cephalopoda
Mollusca: locomotion
generally a muscular foot (not Cephalopoda)
Mollusca: locomotion in Cephalopods
foot is modified into tentacles and they used jet propulsion instead
Mollusca: sensory
complex sensory organs including a brain and eye in Cephalopods
Mollusca: reporduction
monoecious or dioecious?
most are dioecious
The _____ is present in most molluscs except bivalves
radula
radula
rasping mouthpart used for cutting/scrapping make of a chitinous ribbon of minute teeth
feeding: Polyplacophora
herbivore
feeding: Gastropoda
mixed herbivore/carnivore
feeding: Scaphopoda
deposit feeder
feeding: Bivalvia
filter feeder
feeding: Cephalopoda
carnivore
How do land snails and slugs deal with respiration?
vascularized mantle that acts like lungs
Mollusca: respiration
gills mostly, except species on land
Class Gastropoda Subclasses (2)
- Subclass Prosobranchia
- Subclass Heterobranchia
Subclass Heterobranchia Infraclasses (2)
- Infraclass Euthyneura
- Infraclass Plumonata
Class Gastropoda, Phylum Mollusca
Class Cephalopoda Subclasses (3)
- Subclass Ammonoidea
- Subclass Nautiloidea
- Subclass Coleoidea
Subclass Coleoidea Orders (2)
- Order Octopodiformes
- Order Decapodiformes
Defining feature of Class Gastropoda (2)
torsion - body rotates 180º
- anus is above the mouth
What do Heterobranchia have a secondary loss of?
torsion
where are members of Class Gastropoda found?
both aquatic and terrestrial
coiling of the shell: planispiral (2)
- coiling occurs in a single plain
- thought to be the ancestral form
coiling of the shell: conispiral (2)
- coiling creates a spiral in 3D
- sinistral vs. dextral
sinistral
left-handed coiling
dextral
right-handed coiling
what class does Subclass Prosobranchia belong to?
Class Gastropoda
where can members of Subclass Prosobranchia be found?
mainly marine; shelled aquatic snails
Subclass Prosobranchia (2)
what is special about them?
- mantle is modified for form the siphon
- have an operculum
siphon
brings water to the ctenidia
operculum
hard covering over the aperture
what Class does Subclass Heterobranchia belong to?
Class Gastropoda
Where can members of Subclass Heterobranchia be found? (3)
marine, freshwater, and terrestrial snails and slugs
does Subclass Heterobranchia have a shell?
it is very reduced or absent
defining feature of Subclass Heterobranchia
origin
includes gastropods with a gill origin different from that of other members
what Subclass does Infraclass Euthyneura belong to?
Subclass Heterobranchia
Where can members of Infraclass Euthyneura be found? (2)
marine and freshwater slugs
Do members of Infraclass Euthyneura have a shell?
very reduced or absent
What do members of Euthyneura have a secondary loss of?
torsion
What Subclass does Infraclass Pulmonata belong to?
Subclass Heterobranchia
Class Gastropoda - Phylum Mollusca
where can members of Infraclass Pulmonata be found?
land snails and slugs
Phylum Mollusca
what have members of Infraclass Pulmonata lost? (2)
c.o.
- ctenidia, they have a vascularized mantle in its place
- no operculum
infaunal
live within the sediment rather than on top with mouths facing downward
what is the only Class of Mollusca to be exclusively infaunal?
Scaphopoda
where can members of Class Scaphopoda be found?
typically offshore rather than near beaches (marine)
what does Class Bivalvia lack?
a radula
Bivalvia: feeding (2)
most are suspension feeders but some are also deposit feeders
Bivalvia: respiration
they use gills
does Class Bivalvia have good senses?
no, except scallops that have complex eyes
do members of Class Cephalopoda have shells?
very reduced, except for the nautilus
How do members of Class Cephalopoda move?
jet propulsion
chromatophores
cells used for color change
what Class uses chromatophores?
Cephalopoda, for camouflage and warning signs
What Class uses ink sacks?
Cephalopoda
Where is ink discharged?
through the anus
does Class Cephalopoda have good senses?
very developed senses and nervous system
what are regarded as the most intelligent invertebrates?
octopods
hemocoel
blood-filled body cavity
what Class has a hemocoel?
Mollusca
Cephalopoda
what Class does Subclass Ammonoidea belong to?
Cephalopoda
Subclass Ammonoidea (2)
- all extinct
- has distinctive sutures that marked where the septa joined the cell wall
what Class does Subclass Nautiloidea belong to?
Cephalopoda
Subclass Nautiloidea: feeding (2)
scavengers and predators of small animals in coral reefs
what is the only living Cephalopod with an external shell?
the Nautilus
Where can Subclass Nautiloidea be found?
the tropical indo-pacific
what Subclass does Order Decapodiformes belong to?
Subclass Coleoidea
Order Decapodiformes contain what animals? (2)
cuttlefish and squid
how is the shell reduced in cuttlefish?
the cuttlebone
how is the shell reduced in squid?
the pen
how many arms do members of Order Decapodiformes have?
eight arms with two additional tentacles
what Subclass does Order Octopodiformes belong to?
Subclass Coleoidea
where are members of Order Octopodiformes found?
all marine habitats, associated with the ocean floor
do members of Order Octopodiformes have shells?
no
Polyplacophora appear segmented because of the eight -valves- (shells). However, internally, they show no signs of segmentation, and it is not known in other Mollusca. What is the most likely explanation for this?
The eight shell ‘segmentation’ evolved independently in Polyplacophora
What feature is shared by Gastropoda and Polyplacophora?
a large muscular foot
What factor is responsible for the similarity of the large muscular foot shared by Gastropoda and Polyplacophora?
method of locomotion
The term ‘slug’ is used to refer to Gastropods that have lost their shell. Evolutionary loss of a shall has occurred more than once. Which feature would you expect to be shared by different groups of slugs?
A secondary loss of torsion and reduction/complete loss of a shell
the umbo represents what side of the shell?
dorsal, so the other end is ventral
the umbo points in a direction slightly, this direction is?
anterior, so the opposite is posterior
where can the hinge ligament be found?
Bivalvia
the dorsal side
What feature does Scaphopoda and Bivalvia share?
a reduced or absent head
What explains why Scaphopoda and Bivalvia have a reduced/absent head?
their method of feeding
A bivalve way of feeding if ecologically most similar to what other organism?
sponge
Why do you suppose the adductor muscles are so well developed un Bivalvia? (2)
to allow bivalves to keep their shells closed as a defense mechanism (scallops) and to help with better filter feeding
name the three functions of the gills in Bivalves
- reproduction
- filter feeding
- respiration
How are the gills of squid and the gills of clams different from one another?
The gills of squid functions only in respiration, while in clams they are for respiration, feeding, and reproduction
WHy are sensory structures more prevalent on Cephalopoda than on Bivalvia?
Because Cephalopods are highly active predators, they have benefited from advances in their sensory organs, particularly vision. Sessile Bivalves do not need these adaptations.
what are the four body region characteristic of molluscs?
- head
- foot
- visceral mass
- mantle
Which Subclass/Order(s) has gas-filled chambers?
Subclasses Ammonoidea and Nautiloidea
Which Subclass/Order(s) has a reduced shell to an internal ‘bone’?
Order Decapodiformes
Which Subclass/Order(s) has a reduced shell as a ‘pen’?
Order Decapodiformes
Which Subclass/Order(s) has an absent shell?
Order Octopodiformes
Scaphopodoa
Identify the class of the specimen.
Class Polyplacophora
Mollusca
What is the function of the structure indicated by line D?
Locomotion
Identify the class of the specimen.
Bivalvia
What is the function of the structure indicated by line A?
the mantle produces the shell
Identify the structure indicated by line B.
gills
What is structure C?
gills
What is structure A?
branchial heart
What structure is B?
cecum
What is the function of the structure indicated by line E?
reproduction
Is this specimen male or female?
female
nidamental glands
What structure above indicates the specimen’s sex?
nidamental glands (female)
What are some features that contribute to squid as a successful predator? (6)
- well developed eyes
- extensible tentacles with suckers
- siphons for jet propulsion
- fins for maneuvering
- closed circulatory system for gas exchange
- aerodynamic body
The great diversity of molluscs is an example of what evolutionary phenomenon?
adaptive radiation
The cephalopod eye and the vertebrate eye demonstrate what evolutionary phenomenon?
convergent evolution
what is this specimen?
a Nautilus shell
what is this specimen?
a Cuttlefish bone
Class Cephalopoda
A; umbo
what are these specimen?
Class Bivalvia
what specimen made these holes, what Class do they belong to?
Shipworms, Class Bivalvia
what are these specimen?
tusk/tooth shells of Class Scaphopoda
what Class/Subclass/Infraclass do these specimen belgong to?
Class Gastropoda, Subclass Heterobranchia, Infraclass Euthyneura
what Class/Subclass/Infraclass does this specimen belong to?
Class Gastropoda, Subclass Heterobranchia, Infraclass Euthyneura
what Class/Subclass/Infraclass does this specimen belong to?
Class Gastropoda, Subclass Heterobranchia, Infraclass Euthyneura