molluscs Flashcards

1
Q

classes

A

polyplacophora
scaphopoda
gastropoda
bivalvia
cephalopoda

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2
Q

gulf/marsh periwinkle

A

Littorina irrorata
herbivorous, feeds on algae

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3
Q

knobbed whelk

A

Busycon carica

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4
Q

spiral of whelks and lines separating them

A

whorls and sutures

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5
Q

oyster drill

A

Urosalpinx cinerea
carniverous, uses radula and acidic (CaC) secretion to bore thru bivalve shells

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6
Q

Whelks

A

prey on clams
use regella on foot and edge of shell to wedge into clam’s opening

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7
Q

dextral

A

whelks
“right-handed”

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8
Q

Euspira genera

A

moon snails
very wide and flat foot
edge of mantle can roll upwards and partly cover the shell
radula is tongue-like and covered w teeth

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9
Q

what are siphons in Quahogs used for?

A

mostly gas exchange
suspension feeders (form of filter feeding)

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10
Q

Tagelus genus

A

long rectangle guys, spend lives in burrows so muscles holding valves together are very weak

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11
Q

cockles

A

type of bivalve
short siphons, meaning they live close to surface of substrate/very shallowly buried

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12
Q

general morphology of molluscs

A

shell
mantle
foot
mantle cavity
visceral mass
triploblastic/bilateral coelomate hemocoel
complete gut

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13
Q

mantle

A

secretes shell if the organism has one

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14
Q

foot

A

flattened muscular tissue used for crawling/clinging to surfaces
bivalve foot: modified for burrowing
cephalopod foot: modified into arms/tentacles

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15
Q

mantle cavity

A

typically houses gill/lung, anus, nephridopores

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16
Q

visceral mass

A

refers to tissues + organs protected by shell

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17
Q

triploblastic/bilateral coelomate hemocoel

A

hemo-blood: “blood coelum”
open circulatory system in everyone except for cephalopods

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18
Q

open vs closed circulatory system

A

open- works for most sedentary animals, not active
- blood is directly in contact with cells and tissues, heart usually has a slit that pushes blood out when engaged and draws it back in when relaxed

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19
Q

complete gut

A

contains mouth and anus, one direction of movement for food
gut highly differentiated regionally
crystalline style common in bivalves and gastropods

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20
Q

crystalline style

A

gelatinous rod containing digestive enzymes, twirled by beating cilia to release enzymes when rubbing against gastric shield and mix them w food

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21
Q

parts of body wall + shell oof molluscs

A

pallial muscle
shell
extrapallial cavity

22
Q

pallial muscle

A

connects shell to mantle

23
Q

shell

A

periostracum
prismatic layer
nacreous layer

24
Q

extrapallial cavity

A

space btwn shell and mantle epithelium

25
Q

periostracum

A

outermost portion of shell

26
Q

prismatic layer

A

part of shell btwn periostracum and nacreous layer

27
Q

nacreous layer

A

layer btwn prismatic layer and extrapallital space
pearly/iridescent material of the animal

28
Q

polyplacophora (chitons)

A

marine, rocky substrates
8 shell plates
mantle = girdle
herbivores, feed on algal films
radula teeth capped w/ magnetite
foot

29
Q

polyplacophoran mantle

A

specialized to be thick and rubbery- this is where plates are embedded

30
Q

polyplacophoran foot

A

very broad and flat- allows them to adhere to surfaces very tightly

31
Q

cephalization in polyplacophora?

A

very little

32
Q

polyplacophoran mantle cavity

A

“trough” btwn foot and mantle
paired gills located here

33
Q

what kinds of animals are in the class gastropoda?

A

snails, slugs, nudibranchs, sea hares

34
Q

characteristics of gastropods

A

largest group of molluscs
gastro-stomach, pod-foot (stomach-foot)
obvious cephalization
often have shells that act as portable retreats
torsion

35
Q

gastropods that don’t use shells as portable retreats

A

limpets, abalone, slipper shells

36
Q

torsion

A

twisting of visceral mass by 180 deg
occurs in veliger stage of gastropods

37
Q

veliger stage

A

larval stage in gastropods
rudimentary shell, foot visible, 2 large ciliated velum

38
Q

pre-torsion veliger

A

mantle cavity at posterioir end
osphradium also posterior

39
Q

osphradium

A

sensory tissue

40
Q

disadvantages of torsion

A

fouling- repositioning of posterior tissues so that wastes are excreted near the head

41
Q

evolutionary changes made by gastropods to compensate for disadvantages of torsion

A

ciliary tracts to carry away waste
openings/keyholes to excrete wastes (limpets, abalone)

42
Q

hypothetical advantages of torsion in gastropods:

A
  • allows head to be drawn in before foot- incr. chances of sublethal predation vs lethal
  • torsion places osphradium at the anterior end
  • allows mass to be centered over the organism in cases where the apex of the shell spiral is drawn out anteriorally
43
Q

reproduction in gastropods

A

many gonochoristic
some hermaphroditic

44
Q

gonochoristic repro in gastropods

A

spawning (broadcast spawning)
internal fertilization via copulation

45
Q

broadcast spawning

A

in gastropods
gametes emitted to seawater, fertilization occurs in seawater,

46
Q

internal fertilization via copulation in gastropods

A

females may add protective substances to egg case coverings

47
Q

which gastropods are hermaphroditic?

A

sea hares + slugs, nudibranchs

48
Q

gastropod egg development

A

may occur in water or egg casings

49
Q

gastropod larval stages

A

1- trochophore (spinning top)
2- veliger (when torsion occurs)

50
Q

gastropods that don’t use shells as portable retreats

A

limpets, abalone, slipper shells