Term
| Name the defining features of a mollusc |
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Definition
True coelom confined to space around heart (but have haemocoel)
Shell, mantle, mantle cavity, gills (ctenidium), visceral mass, foot, radula |
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Term
| Can molluscs reproduce asexually and be monoecious? |
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Definition
| Can be monoecious (hermaphroditic) but can only reproduce sexually. |
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Term
| Name the layers of the typical molluscan shell |
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Definition
| Outer periostracum, middle prismatic CaCO3, inner nacreous CaCO3 |
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Term
| Molluscs are protostomes and therefore exhibit schizocoelus triploblasty and radial cleavage |
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Definition
| True except protostomes exhibit spiral mosaic cleavage not radial. |
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Term
| Name the three most common groups of molluscs and their key features |
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Definition
Gastropods (operculum on foot, trochophore & veliger larva, Shell undergone torsionpneumostome)
Bivalvia (Loss of radula, foot and incurrent/excurrent siphons, head reduced, complex gills, hinged shell, laterally flattened)
Cephalopoda (all marine and active predators, foot merged with head, sophisticated eyes, no cilia on gills, closed circulatory system, gas filled chambers separated by septa, highly developed nervous system |
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Term
| When do gastropods undertake their final 90 degree rotation? |
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Definition
| Just before metamorphosis into adult |
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Term
| Describe the body plan of the ancestor of the gastropod to the body plan of derived gastropods |
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Definition
Monoplacophoran, cap like shield, dorsoventrally flattened.
Coiled retreat shell, conispiral (not planispiral), coiling for gravity, loss of gill, kidneys and atrium on right side. |
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Term
| Are all derived gastropods torted? |
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Definition
| Some have reverted through detortion |
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Term
| Describe a basal radula and give and example of a derived radula |
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Definition
Basal: Protrusible conveyor belt with teeth, using rasping action (deposit feeding)
Derived: Harpoon in cone snails for injecting neurotoxin. |
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Term
| Name the key features of monoplacophorans and polyplacophorans |
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Definition
Mono: some serial repetition of organs, not homologous to annelida. Ancestral body plan
Polyplacophorans: DV-flattened, reduced head, 7-8 plates to shell, no veliger larva stage |
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Term
| Key features of scaphopoda include: |
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Definition
| No eyes, radula uses ciliary action, mantle wraps around viscera, gills lost, food adheres to foot or captacula |
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Term
| What are the consequences of coiling and torsion in gastropods and how do they control it? |
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Definition
| Fouling of mouth/gills. Regulated by water current |
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Term
| Coiling and torsion is part of ____ development |
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Definition
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Term
| The three major classes of gastropods and their features are: |
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Definition
Prosobranch= primitive gill condition, siphon mantle
Opisthobranch=almost all marine, lost or reduced shell, detorted
Pulmonates= terrestrial snails and slugs, gas filled vascular cavity, pneumostome, loss of gills, some detorted and moved back into water and evolved gills. |
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Term
| What is in some cephalopods skin that helps them with camouflage and communication? |
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Definition
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Term
| Where are statocysts of molluscs located? |
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Definition
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Term
| Basal bivalvia have paired gills and little folding, True or false |
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Definition
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Term
| What manipulates food into Bivalve mouths? |
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Definition
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Term
| Describe basal and derived gills in molluscs |
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Definition
Basal=attaching membrane, skeletal rod, cilia beat
Derived=countercurrent exchange |
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Term
| Molluscs undergo radial cleavage. True or false? |
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Definition
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Term
| What is the function of the pneumostome |
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Definition
| Opening in gastropod mantle cavity for gas exchange, it is small to prevent excess water loss. |
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Term
| Gastropod kidneys and atrium are found on which side of the body? |
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Definition
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Term
| Gastropods only have veliger larvae stage, True or False |
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Definition
| Falsel, also have trochophore |
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Term
| Bivalvia are dorsoventrally flattened, true or false? |
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Definition
| False, they are laterally flattened |
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Term
| All gastropods have an open circulatory system, true or false |
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Definition
| Falso, cephalopods have a closed circulatory system |
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Term
| What is the name of the tissue that connects cephalopod chambers? |
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Definition
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Term
| What drives the jet propulsion seen in cuttlefish? |
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Definition
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Term
| Melanin pigment sacs in some cephalopds have what function? |
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Definition
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Term
| Cephalopods can be monoiecous or dioecious, true or false? |
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Definition
| False, they are all dioecious |
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Term
| What structure passes the spermatophore into the female mantle cavity in an octopus? |
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Definition
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Term
| Young octupus hatch as miniature adults, true of false? |
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Definition
| True, no free swimming larval stage. |
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