Mollusca Flashcards

1
Q

four clades in Mollusca

A
  1. Gastropoda
  2. Placophora
  3. Bivalvia
  4. Cephalopoda
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2
Q

main traits found in ALL the clades of Mollusca

A
  1. circulation and respiration
  2. feeding
  3. reproduction
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3
Q

what is included in Phylum Mollusca

A
  1. snails
  2. slugs
  3. oysters
  4. clams
  5. octopuses
  6. squids
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4
Q

habitat of Phylum Mollusca

A

most are MARINE but some are freshwater and terrestrial

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5
Q

describe the body of Mollusca

A

soft-bodied with most have a hard shell protecting them

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6
Q

key traits in Mollsuc development

A
  1. protostome
  2. bilateral
  3. triploblastic
  4. coelomate
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7
Q

ALL molluscs have a similar body plan with THREE main parts

A
  1. foot
  2. visceral mass
  3. mantle
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8
Q

what are the morphological synapomorphies of phylum Mollusca

A
  1. foot
  2. visceral mass
  3. mantle
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9
Q

what do MANY (NOT ALL) Molluscs have

A
  1. water-filled mantle cavity
  2. rasp-like radula
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10
Q

visceral mass function

A

area under the mantle that holds the internal organs

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11
Q

mantle function

A

found in ALL molluscs and its a tissue that CAN secrete the shell IF the mollusc has one

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12
Q

foot function

A

aids in locomotion

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13
Q

what makes up the tentacles of octopuses

A

the foot

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14
Q

are MOST molluscs dioecious or hermaphrodites

A

dioecious (separate sexes)

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15
Q

where are gonads found

A

in the visceral mass

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16
Q

what is an exception to most molluscs being dioecious

A

snails - they are hermaphrodites

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17
Q

habitat of MOST molluscs

A

marine

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18
Q

what is the second most diverse phylum

A

Mollusca

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19
Q

what is THE most diverse phylum

A

insects

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20
Q

four species in Phylum Mollusca

A
  1. gastropods
  2. chitons
  3. Bivalves
  4. Cephalopods
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21
Q

habitat of gastropods

A

marine

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22
Q

do gastropods have a shell (MOST) and if so describe it

A

yes - single, spiraled shell

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23
Q

most distinctive characteristics of gastropods is

A

torsion - where the anus and mantle end up ABOVE the head (switched from normal)

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24
Q

when do we see the first evidence of open vs closed circulatory system

A

in gastropods

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25
Q

closed vs open circulatory system

A

closed
1. blood is SEPARATE from interstitial fluid

open
1. blood is MIXED with interstitial fluid (now called hemophyl)
2. CANNOT USE THE TERM BLOOD

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26
Q

feeding of gastropods

A

“grazers”

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27
Q

do gastropods have a complete gut

A

YES

28
Q

least to most inclusive

A

gastropods: Clade Mollusca: Lophotrochozoan: Bilateria: Eumetazoa: Metazoa

29
Q

what does circulation look like in gastropods

A

open system of vessels

30
Q

compare respiration of terrestrial/freshwater and marine gastropods

A

terrestrial
mantle cavity forms “lungs”
siphon brings in oxygen to the INTERNAL gills

Marine
respiration via gills in the mantle cavity
gills are exposed to the water

31
Q

marine vs freshwater/terrestrial gastropods reproduction

A

marine
1. species are dioecious (separate sexes)
2. have complex life-cycle

Freshwater/terrestrial
1. species are hermaphroditic (both sexes in one)
2. direct development

32
Q

least to most inclusive

A

Chitons: Phylum Mollusca: Lophotrochozoan: Bilaterian: Eumetazoan: Metazoan

33
Q

how can one distinguish chitons from other molluscs

A

their armour made of eight dorsal plates

34
Q

habitat of chitons

A

ALL marine

35
Q

how do chitons use their foot

A

like a suction cup to grip rock

36
Q

how do chitons use their radula

A

to scrape algae off rock surfaces

37
Q

least to most inclusive

A

Bivalves: Phylum Mollusca: Lophotorocozoan: Bilaterian: Eumetazoan: Metazoan

38
Q

Bivalves include

A
  1. clams
  2. oysters
  3. mussels
  4. scallops
39
Q

how did bivalves get their name

A

they have a shell divided into two halves (valves) held together by very strong adductor muscles

40
Q

why are bivalves hard to open

A

their powerful adductor muscles close the shell for protection

41
Q

what do bivalves use for digging or anchoring

A

their foot

42
Q

what are gill used for in bivalves

A
  1. feeding
  2. respiration
  3. reproduction
43
Q

are bivalves sessile or motile

A

most are sessile

44
Q

how do bivalves feed

A

they are suspension feeders

45
Q

suspension feeding

A
  1. ciliated gills create water currents
  2. gills trap fine food-particles in mucus coat
  3. water flows into the mantle cavity via the incurrent siphon, passes over gills, and exists via the excurrent siphon
46
Q

how are bivalves, gastropods and chitons all similar

A

all have open circulation

47
Q

marine vs freshwater bivalve reproduction

A

marine
1. mostly dioecious
2. trochophore larvae

Freshwater
1. most are hermaphorditic
2. direct development

48
Q

what clade of molluscs have glochidia

A

bivalves

49
Q

the function of glochidia in bivalves

A

an immature freshwater mussel life stage modified for a parasitic existence; released larvae may attach to host species and be taken away from parent

50
Q

do freshwater or marine bivalves have glochidia

A

SOME freshwater bivalves

51
Q

least to most inclusive

A

Cephalopods: Phylum Mollusca: Lophotrochozoan: Bilaterian: Eumetazoan: metazoan

52
Q

Cephalopods include

A
  1. squids
  2. octopuses
  3. cuttlefish
  4. nautiluses
53
Q

Cephalopods traits

A
  1. beak-like jaw surrounded by tentacles
  2. well-developed sense organs and complex brain
54
Q

what was modified in Cephalopods to become tentacles

A

the foot

55
Q

how do squids swim

A

use their siphon to fire a jet of water which allows them to swim

56
Q

how many shelled species make up the Cephalopods

A

JUST ONE - Nautiluses

57
Q

how do Cephalopods breath

A
  1. water passes in through the in-siphon
  2. water passes over the gills so the oxygen can be trapped
  3. water is passed out the out-siphon
58
Q

what are some examples of well-developed sense organs in Cephalopods

A
  1. advanced predatory techniques
  2. communication (like chromatophores)
  3. ability to learn
  4. the unique Cephalopods eye
59
Q

what are chromatophores in Cephalopods

A

they are the connection between the brain and the skin via the eye

60
Q

describe the pattern of neurons in Cephalopods

A

NOT isolated to the brain, but are spread out through all the arms

61
Q

describe how the Cephalopods eye can be seen as “better” then vertebrates

A

they have evolved to LACK a blind spot which can be found in vertebrates

62
Q

compare squid vs octopus feeding

A

squid
1. use siphon to fire a jet of water which allows them to swim very quickly and catch prey

octopus
1. creep along the sea floor in search of prey

63
Q

how do Cephalopods CONTRAST to all the other molluscs

A

they have a CLOSED circulatory system

64
Q

reproduction traits of Cephalopods

A
  1. dioecious
  2. direct development (no larvae)
  3. many are semalparous
  4. transfer of spermatophore
65
Q

what does it mean that many Cephalopods are semelparous

A

reproducing or breeding only once in a lifetime before they die