AD Molluscs Flashcards

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1
Q

Describe a mollusc’s shell

A

Early molluscs had a proteinaceous and chitinous cuticle
Progressively reinforced with calcium
Modern shells consist of crystals of calcite and argonite deposited within a framework of layers of protein (conchiolin)
Muscles pull the shell down to protect the head and foot when needed
Often conical or helically coiled

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2
Q

The contraction of which 2 muscles protracts the odontophore and radular ribbon through the mouth?

A

Radular protractor muscle

Odontophore protractor muscle

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3
Q

What part of a mollusc’s body is generally used to identify a mollusc remains from the guts of predators

A

Radula teeth

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4
Q

Describe an Aplacophora

A
No shell
Calcerous spines
Worm like
<300mm
Headless and no proper foot
Live in marine sediments
Most have a radula but no excretory organs
Hermaphrodites
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5
Q

Describe a Polyplacophora (chitons)

A
8 overlapping plates
Can roll into a ball
Girdle of spiny cuticle
<400mm
Powerful foot
Marine eg shores
Kidneys but head poorly defined
Radula
6-88 pairs of ctenidia
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6
Q

What are ctenidia?

A

Gills

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7
Q

Describe a Monoplacophora

A
Conical shell
<30mm
Weak foot
Marine eg deep trenches
Head poorly defined and no eyes/tentacles
6 pairs of kidneys
Radula
Detrital feeders
Mantle cavity around foot
3-6 pairs of ctenidia
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8
Q

Describe a Scaphopoda (tusk shells)

A
Cylindrical shell
<150mm
Separate sexes
Burrowing foot
Marine sediments
Head, no eyes but a radula
Mantle cavity through body
No ctenidia
Ciliated contractile tentacles
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9
Q

Describe a bivalvia

A

Pair of shells
<1m
Separate sexes
Some use foot to burrow or others cemented to substrate (byssus)
Head has no eyes, no tentacles, no radula
May be tentacles around eyes or mantle
Ctenidia highly modified

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10
Q

Describe a gastropoda

A

Snail
Largest and most diverse group
Torsion
Single coiled shell with operculum (generally)
Well developed head with eyes, radula and sensory tentacles
Well developed crawling foot
May be gonochoristic or hermaphrodites

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11
Q

Describe gastropoda torsion

A

Rotation of visceral hump through 180°
Mantle cavity now faces forward
Anus discharges into mantle cavity over the head
Having the mantle cavity at the front allows the well-developed head to be withdrawn into the shell
Chemoreceptors within the mantle cavity can now monitor the water ahead, rather than behind

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12
Q

Describe Gastropoda - Superorder Opisthobranchia

A

Sea-slugs, sea-hares
Secondary gills or papillate body surface
Up to four pairs of tentacles
Most are carnivores
Includes planctonic mucus net feeders (pteropods) with ciliated wings

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13
Q

Describe Gastropoda - Superorder Pulmonata

A

Mainly terrestrial or freshwater
Mantle cavity evolved into air-breathing lung with pneumostome
Shell thinned or lost
Most are grazers of plants or fungi, some carnivores

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14
Q

Describe Gastropoda - Superorder Pulmonata Anatomy

A

Mantle cavity, heart, kidney, salivary gland, digestive gland, rectum, reproductive system, brain, foot

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15
Q

What is a Cephalopod?

A

Squid, octopus, cuttlefish

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16
Q

What is a Cephalopod’s body plan?

A

Mantle cavity opens forwards
Rapid, directed movement effected by expelling water through manoeuvrable funnel
Prey caught with arms/tentacles, chewed up by beak then radula
Gonochoristic and most are short lived (1-2 years)
90° body tilt then elongation

17
Q

Describe a Cephalopod - Nautiloidae

A

Body is in external shell
Last segment is inhabited
Siphuncule controls gas/water balance in other chambers to control buoyancy
Poor swimmers – water expelled by funnel muscle
80-90 suckerless tentacles
Two pairs of ctenidia and kidneys
Nervous system and eyes simple

18
Q

Describe the anatomy of Cephalopod - Celeoidae - Sepiida, Cuttlefish

A

Stomach, digestive gland, shell, salivary gland, brain, buccal mass, funnel, gonad, ink sac, fin, gill

19
Q

Describe the anatomy of Cephalopod - Celeoidae - Teuthida, Squid

A

Stomach, digestive gland, brain, ‘pen’, buccal mass, ink sac, funnel, crop, mantle, siphon, parrot-like beak and mouth, 8 arms and 2 rows of suckers, 2 long feeding tentacles

20
Q

Describe the anatomy of Cephalopod - Celeoidae - Octapoda, Octopus

A

Brain, digestive gland, buccal mass, crop, kidney, funnel, branchial heart (3?), salivary gland

21
Q

Describe an Octopus’ brain

A

Large optic lobes

Vertical lobe, optic stalk, brachial lobe,

22
Q

What do the bivalve gills demonstrate?

A

How organs that originally evolved for one function can be further adapted for use in totally different ways
Bivalve mollusks breathe through their gills. As filter feeders, bivalves gather food through their gills.

23
Q

What are the classical features of the Coleoidea?

A

the large brain, the advanced eye structure, powerful jet propulsion, control over their own body patters and colours, multifunctional tentacles and a vascular system with veins and arteries