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BISC 306 > Molluscs (+Brachiopods) > Flashcards

Molluscs (+Brachiopods) Flashcards

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1
Q

what are the names of layers in a mollusc shell?

A

outer = periostracum (organic)
middle = prismatic (calcium carbonate without magnesium)
inner = nacreous (calcium carbonate with magnesium)

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2
Q

what is the name of the ciliated gas exchange structure used by molluscs?

A

ctenidium

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3
Q

what features make a mollusc’s gas exchange system effective?

A
  • ciliated
  • bipectinate (forked, increases SA)
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4
Q

what feeding structures do molluscs have?

A
  • radula (chitinous invagination of pharynx)
  • odontophore (sits underneath radula)
  • retractor muscles
  • protractor muscles
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5
Q

what structures do molluscs use to move around?

A
  • foot (ventral muscular extension)
  • pedal retractor muscles
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6
Q

Gastropods
what shape are gastropods’ shells?

A

single and spiraled

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7
Q

Gastropods
what is the name of the group of gastropods without a shell?

A

opisthobranchs (nudibranchs)

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8
Q

Gastropods
what common species are found in Gastropoda?

A
  • limpets (cone shaped shell)
  • snails (spiral shell)
  • opisthobranchs (nudibranchs)
  • ‘sea slugs’ (no shells)
  • sea angels
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9
Q

Gastropods
what are the three types of nudibranchs?
what characteristics define each one?

A

dorid = has gill plume on posterior end of dorsal side
dendronoid = has branched cerata (dorsal projections)
aeonid = has cerata (dorsal projections)

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10
Q

Gastropods
what are the three groups within Gastropoda?

A
  • prosobranchs (have siphons for water entry and osphiradiums) –> sea snails, limpets etc.
  • opisthobranchs (lack or have reduced shells) –> nudibranchs
  • pulmonata (have land based respiration instead of ctenidia) –> snails, slugs
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11
Q

Gastropods
what unique trait allows cone shells to be effective predators?

A

barbed radula with toxins and pheromones

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12
Q

Gastropods
describe the pathway of gastropod circulatory systems

A
  • oxygen enters blood stream via ctenidia
  • oxygenated blood goes to heart
  • heart pumps oxygenated blood into hemocoel
  • deoxygenated blood from hemocoel returns to ctenidia
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13
Q

Gastropods
what kinds of nephridia do gastropods have?

A
  • excretory
  • reproductive
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14
Q

Gastropods
what disparities do gastropods have?

A
  • well developed heads
  • torsion (twisted internal structure)
  • shell coiling
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15
Q

Gastropods
what are the axis of symmetry for gastropods?

A

anterior = mouth end
posterior = anus end

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16
Q

Gastropoda
what feeding techniqiues can a gastropod have?

A
  • grazing
  • suction
  • drilling
  • photosynthesis
  • suspension
  • toxic harpooning
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17
Q

what three classes have veliger stages after being a trochophore?

A
  • bivalvia
  • scaphophora
  • gastropoda
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18
Q

describe the veliger larva stage

A
  • has a velum (projected cilliar disc) for swimming and feeding
  • develops a mantle shell
  • can swim far distances
  • develops into adults once settling down
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19
Q

Polyplacophora
what are the common names of polyplacophores?

20
Q

Polyplacophora
what is unique about polyplacophore mantles?

Study These Flashcards
A

made up on 8 plates versus the typical 1

21
Q

Polyplacophora
what feeding niche do polyplacophores fill?

22
Q

Polyplacophora
what disparities do chitons have?

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A
  • reduced central nervous system
  • has hundreds of small eyes along plates
  • no tentacles
23
Q

Scaphopoda
describe the shell of a scaphopod and how it is used

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A
  • long, tubular shell with an opening at the tip
  • water enters and exits through the tip
24
Q

Scaphopoda
how do scaphopods eat?

Study These Flashcards
A

uses sticky bulbs on feeding tentacles at the foot pick out organic matter in sediment

25
**Scaphopoda** what are the axis of a tusk shell? (up/down/left/right)
pointing up = dorsal pointing down = ventral left = anterior (concave) right = posterior (convex)
26
**Scaphopoda** what disparities do scaphopods have?
- orientation (L/R --> anterior/posterior) - no ctenidia
27
**Bivalvia** what common species are found in Bivalvia?
- scallops - clams - oysters - mussels - cockle
28
what do infaunal and epifaunal mean?
infaunal = buried in sediment epifaunal = live on top of benthic sediment
29
**Bivalvia** what disparities do bivalves have?
- no head - no radula (filter feed instead) - no odontophore
30
**Bivalvia** what are the axis for clams and oysters?
left = left shell (curls to the right) right = right shell (curls to the left) ventral = "mouth" opening (far from hinge) dorsal = hinge side anterior = shorter outer edge posterior = longer outer edge (siphon is here)
31
**Bivalvia** what are the axis for mussels?
posterior = wide end anterior = narrow end ventral = arched or flat end dorsal = wide end left = right of hinge right = left of hinge
32
**Bivalvia** what are the axis for scallops?
left = facing up right = facing down anterior = larger auricle posterior = smaller auricle ventral = "mouth" end dorsal = hinge end
33
**Bivalvia** briefly describe the path of water through a bivalve
water enters via incurrent siphon (ventral) and exits via excurrent siphon (dorsal)
34
**Bivalvia** how do bivalves feed?
- food enters via mucus strings - labial palps filter through food and directs edible materials into mouth - after digestion, excretion exits the anus near the excurrent siphon
35
**Bivalvia** what differences in siphons do infaunal and epifaunal bivalves have?
infaunal (buried) = long siphons epifaunal (above surface) = short siphons
36
**Bivalvia** how do bivalves open and close their shells?
adductor muscles relax = shell opens adductor muscles contract = shell pulls shut
37
**Aplacophora** what disparities do aplacophores have?
- reduced foot - reduced mantle (single pair of ctenidia) - reduced shell (no shell, has spicules) - reduced head (no eyes/tentacles) - no specialized sensory/feeding structures
38
**Cephalopoda** what are the axis of a squid?
ventral = arm end dorsal = fin end anterior = opposite to funnel posterior = side with funnel
39
**Cephalopoda** what disparities do cephalopods have?
- highly derived CNS (large brain) - reduced/lost shell (exception = nautilus) - foot has become tentacles, funnel and arms - closed circulatory system - head is ventral not anterior - mantle is muscular
40
**Cephalopoda** what do siphuncles do in a nautilus?
maintains buoyancy by regulating gas
41
**Cephalopoda** what structure helps squid and octopus hunt?
chitinous beak on mouth
42
**Cephalopoda** describe the pathway for food in a squid
- mouth - esophagus - stomach - caecum (digestive enzymes here) - intestines - anus
43
**Cephalopoda** describe the pathway for blood flow in a squid
- 2 branchial hearts bring deoxygenated blood to ctenidia - ctenidia sends oxygenated blood to systemic heart - systemic heart pumps blood to body and returns to branchial hearts
44
**Cephalopoda** how do squids pump water to ctenidia?
muscle contraction (versus cilia current)
45
**Cephalopoda** describe the pathway for sperm in a squid
- produced in testis - passed through sperm duct (vas deferens) - seminal vesicle packages sperm into spermatophores (coated with cement body) - passed to spermatophore sac - hectodactyl arm pulls spermatophores out for insemination
46
**Cephalopoda** describe the pathway for eggs in a squid
- created in ovary - passed through ovaduct - oviducal, nidamental glands package eggs into ribbons - fertilized eggs secreted out funnel
47
**Brachiopods** how do brachiopods differ from bivalves?
- brachiopod = shells are dorsally/ventrically symmetrical bivalves = shells are left/right symmetrical - 2 sets of muscles used to control shells (abductor and adductor) vs one set of bivalves (adductor) - lophophore used for gas exchange vs ctenidia

BISC 306 (14 decks)

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