Mollusca 1 Flashcards
1
Q
Intro
3 points
A
- Second largest phylum
- Large degree of morphological diversity
- Occupy all major habitat types
2
Q
Classification
A
Kingdom: metazoa
Phylum: Mollusca
8 Classes: Caudofoveates, Salanogastes, Chitons, Monoplacophora, Scaphopods, Bivalves (most), Gastropods (most), Cephalopods
3
Q
3 most universal features defining modern molluscs
A
- mantle with a significant cavity used for breathing and excretion
- presence of a radula (except for bivalves)
- structure of the nervous system.
4
Q
Visceral =
A
Collection of tissues joined in unit for common functionality
5
Q
Radula –
A
anatomical structure used for feeding.
6
Q
Key characteristics
A
- Buccal region with radula, ribbon like, heavily modified.
- Through gut (complete, regional specialisation) and kidneys
- Gas exchange by ctenidial gills housed in mantle cavity
- Separate sexes (dioecious)
- Trochophore and veliger larva
7
Q
Body structure
Body wall recognisable layers
3 points
A
- cuticle, epidermis (ciliated) and muscles
- Mantle and mantle cavity (water contact)
- Ctenidia (Ctenidial gills)
Central flattened longitudinal axis
Triangular filaments (alternate along longitudinal axes)
Water driven between filaments by cilia
8
Q
Body structure
Calcareous shell
5 points
A
- Most solid shell (aragonite calcite)
- Shell glands in mantel
- Calcium carbonate layered
- Thin organic surface coating
- Multiple/Single/internal/no shells
9
Q
Body structure
Torsion
6 points
A
- Occurs during development in all gastropods
During late veliger larval stage - Rotation of the visceral mass, mantle and shell
- Anticlockwise direction
- Two-step process
First rapid 90° twist
Slower second 90° twist (tissue growth) - Torted or detorted
- Gastropod: one aperture in shell
10
Q
Locomotion
5 points
A
- Crawling
- Burrowing
- Boring
- Swimming
- Sedentary/sessile
Byssal threads
11
Q
Feeding
radula 3 points
A
- Radula membrane
Radular protractor and retractor muscles
2.Radula sac
- Odontophore
Hard calcareous structure
Odontophore protractor and retractor muscles
12
Q
Feeding
2 points
A
- Macrophagy
Herbivores
Predators
Scavengers - Microphagy
Suspension feeders - most vegetarians
13
Q
Reproduction
5 points
A
- Sexual
- Dioecious
- External fertilisation
Indirect development
Trochophore larva
Veliger larva (velum) - Internal fertilisation
Direct and mixed development
Egg brooding - Hermaphrodites
14
Q
Chromatophores
3 points
A
- pigment-containing and light-reflecting cells
- Controlled by nervous system
- Expanded and contracted by muscle cells
15
Q
ink sacks
4 points
A
- Located near intestine
- Dark fluid containing melanin pigment
- Alarm response, blinding attackers.
- Used in contract to bioluminescence in permanently dark environments,
16
Q
highly divergent grouo
A
squids clams and slugs
17
Q
most advanced
A
squids and cuttlefish
18
Q
diversity in molluscs - hypothetical generalised mollusc used to illustrate
4 points
A
- bilaterally symmetrical
- single “limpet-like” shell (secreted by mantle
covering the upper surface) - The underside is a muscular
“foot”. - The visceral mass, is the non-muscular metabolic region
containing the body organs
19
Q
extinction
A
- 2 families extinct
2. various molluscs brink of extinction
