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Zoology > Week 6 > Flashcards

Week 6 Flashcards

1
Q

Phylum Mollusca characteristics

A 
"soft"
lophotrochozoa
protostomes
coelomates
90,000 species
marine, freshwater, and terrestrial
herbivorous grazers, predatory carnivores, filter feeders, parasites
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2
Q

first group of larger animals to transition to land

A

Phylum Mollusca

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3
Q

what is possible the second largest group after anthropods

A

Mollusca

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4
Q

what do molluscs have on pseudocoelomates

A 
true coelom
advanced locomotion
circulatory system (open or closed) with heart and vessels
respiratory organs (lungs or gills)
complex sensory structures (highly developed eyes in cephalopods)
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5
Q

what does the coelom surround in molluscs

A

the heart

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6
Q

are molluscs eyes analogous or homologous with human eyes

A

they are analogous

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7
Q

mollusc definition

A

coelomate protostomes possessing a shell-secreting mantle, also possessing a radula, digestive gland, metanephridia, gills, and an open or closed circulatory system with a heart

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8
Q

metanephridia

A

simple kidney, similar to protonephridia,

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9
Q

what does the metanephridia help with

A

excretion

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10
Q

where are protonephridia generally found in

A

things without a coelom or vascular system,

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11
Q

where are metanephridia found in

A

things with a coelom and vascular system

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12
Q

Molluscan diversity

A

Class Caudofoveata & Class Solenogastres- small group of worm like animals, mainly deep sea
Class Polyplacophora & Class Monoplacophora- “many plates” (chitons) or “one plate”
Class Scaphopoda- “shovel foot”, tusk/tooth shells
Class Gastropoda- snails and slugs, largest mollusc group
Class Bivalvia- clams, mussels, mostly filter feeders, some freshwater forms
Class Cephalopoda- squids, octopuses

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13
Q

Class Caudofoveata & Class Solenogastres

A

lack shells but have a calcareous scales or spicules in skin

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14
Q

Class Polyplacophora & Class Monoplacophora

A

chitons with 7-8 plates, monoplacophora have one cap-like shell
rocky intertidal surfaces
don’t move much, chitons curl up into ball when dislodged
serial repetition of soft parts (gills) seen in monoplacophorans

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15
Q

Class Scaphopoda

A

tube shells open at both ends, burrow larger head into sand, leave smaller end open to water

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16
Q

how much does class Gastropoda make up of all living mollucs

A

80%

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17
Q

some molluscs that are important food sources

A

escargot, abalone

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18
Q

Class Cephalopoda

A

foot modified into arms
active predators
well developed nervous and sense organs, closed circulatory system

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19
Q

Phylum Mollusca overall complexity

A

head-foot
visceral mass
mantle
shell

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20
Q

head-foot

A

most have a distinct head with a mouth (containing radula) and sensory organs
foot is chief locomotor organ, modified in different ways in different groups

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21
Q

visceral mass

A

contains organs, digestion, circulation (heart connects to gills), excretion (metanephridia), reproduction

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22
Q

mantle

A

mantle cavity is space between protective mantle (which secretes shell) and the body, houses gills or lungs

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23
Q

what is essentially molluscs body

A

head-foot and visceral mass

can be extended to include mantle

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24
Q

phylum mollusca

complexity and feed

A

uses teeth on radula to rasp off bits of food from hard surfaces
supported by odontophore

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25
Q

odontophore

A

cartilaginous rod
supports radula
attachment for muscles

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26
Q

radula

A

protruding, rasping, tongue-like organ

radula teeth made of chitin, constantly replaced (produced posteriorly, used at apex, lost anteriorly)

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27
Q

how is feeding modified in some molluscs

A

bivalves- filter feeders

cephalopods- beak and jaws for seizing prey

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28
Q

phylum mollusca

visceral mass- digestive system

A

digestive system more complex and generally highly specialized to correspond with feeding habits
radula brings food into mouth, digestive gland secretes enzymes for digestion in stomach

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29
Q

phylum mollusca

visceral mass- circulatory system

A

no distinction between blood and interstitial fluid- hemolymph
open system more common in slow moving animals, more active animals (like cephalopods) generally need a closed system because it is more efficient
heart pumps blood out to body, muscles move blood back to gills.

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30
Q

pericardium

A

fluid-filled sac, encloses the coelom (and the heart)

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31
Q

how does circulation occur

A

heart pumps blood to body, muscles move blood back to gills

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32
Q

what does hemocyanin do

A

acts as O2 carrier, has two copper atoms that reversibly bind a single oxygen molecule, binds O2 at gills where it is abundant and releases it in tissues where there is a deficit

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33
Q

what color blood does molluscs have

A

blue

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34
Q

phylum molluscs

visceral mass- excretory system

A

metanephridia are similar to protonephridia but inside of the tube is ciliated to move fluid
organisms with vascular system and coelom have filtration and excretion happening in two different sites

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35
Q

phylum mollucs

response to stimuli and movement

A

muscular foot

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36
Q

muscular foot

A

usually ventral
attachment or locomotion
sometime secrete mucous for adhesion or to help glide on cilia

37
Q

modifications to muscular foot

A

attachment disc of limpets
hatchet foot of bivalves
siphon and arms of cephalopods

38
Q

mantle

A

sheath of tissue on each side of body

forms lobes at outer edge

39
Q

what does the mantle secrete

A

shell (if there is one)

40
Q

what does the mantle cavity house

A

gills/lungs

41
Q

what does the exposed mantle surface function in

A

gaseous exchange

42
Q

what systems empty into mantle cavity and out to environment

A

excretory and reproductive

43
Q

what does the mantle in aquatic forms usually contain

A

chemoreceptors

44
Q

what does cilia in mantle cavity do

A

form water currents to carry waste and reproductive products out and bring in oxygen and, in filter feeding forms, food

45
Q

layers of shell

A

periostracum
prismatic layer
nacre

46
Q

periostracum

A

organic layer or “skin” made of protein, protects underlying layers

47
Q

prismatic layer

A

protein and calcium carbonate, secreted at mantle edge

48
Q

nacre

A

mother of pearl, in thin translucent sheets, secreted by epithelium so older parts of shell have thicker layers

49
Q

how is a pearl formed

A

when something is lodged between mantle and nacre, mantle secretes layers of nacre around it as a defensive mechanism

50
Q

phylum mollusca reproduction

A

usually reproduce sexually ( some parthenogentic- development without fertilization)
most are dioecious
some simultaneous hermaphrodites- gonads= ovotestis
shed eggs/sperm into mantle cavity and then out into environment for fertilization
free swimming trochophore stage is characteristic in aquatic species, often followed by a veliger stage

51
Q

veliger stage

A

has beginnings of foot, shell, and mantle

52
Q

is veliger stage seen in cephalopods

A

no, they hatch miniature adults

53
Q

class gastropoda critters

A

snails, slugs, conchs, nudibranchs

54
Q

class bivalvia critters

A

clams, mussels, oysters, scallops

55
Q

class cephalopoda critters

A

squids, octopuses, nautiluses, cuttlefishes

56
Q

gastropoda

A

largest and most diverse mollusc group
body elongated dorso-ventrally and then coiled inside shell; also turn whole shell around so that anus is over head (torsion)

57
Q

how does gastropoda move

A

usually through waves of muscular contraction in foot, may be mediated by cilia and/or mucus; tend to be pretty sluggish

58
Q

what do pulmonate land gastropods have

A

mantle cavity developed into simple lung

59
Q

gastropod quirks

A

torsion
coiling
strategies to avoid fouling

60
Q

where is veliger larva mouth and anus

A

mouth anterior, anus posterior

61
Q

torsion

A

start with straight mouth to anus tract in veliger, then muscles start to contract and shell (and viscera inside) are pulled 0 degrees
mantle cavity starts to form near anus, and continue rotating (shell mostly stays put) until anus and mantle cavity are in front
occurs during development

62
Q

what does putting butt over head do

A

increases possibility of wastes washing back over gills and mouth (fouling)

63
Q

why does torsion happen

A

moves respiratory organ to anterior, might increase efficiency
mantle cavity has chemosensitive organs, so makes sense to move it in front to better sample water/air in the direction it is headed
may make it easier to withdraw head inside shell

64
Q

did coiling or torsion evolve first

A

coiling

65
Q

coiling

A

ancestral planospiral shell is not very compact and has high center of gravity
evolved into more compact form with successive whorls lying outside preceding one
this is unbalanced so it shifted over, excess weight on right side led to loss of kidney and gill on right side

66
Q

what made the adaptations to avoid fouling happen

A

loss of gill

67
Q

adaptations to avoid fouling in gastropods

A

water flows one way into left side and out of right side

circulation through mantle cavity has been modified to move gill to anus and then out of mantle cavity

68
Q

how do cone snails eat

A

with modified hollow barbed radula tooth to stab and inject venom into prey before engulfing it

69
Q

what does conotoxin do

A

immobilize prey and then harpoon is retracted and prey is eaten

70
Q

can conotoxin be dangerous to humans

A

yes

71
Q

how is conotoxin useful in medical research

A

venom in precise and fast acting, allowing quick results with few side effects
also contains pain reducing compound

72
Q

snail love darts

A

dart success not related to copulation success or size of ensuing sperm donation
BUT dart success increases amount of sperm stored by recipient
AND dart success increases relative paternity when competing with an unsuccessful dart shooter

73
Q

where does interanal fertilization required to occur in gastropods

A

to live on land

requires more complicated reproductive system

74
Q

class bivalvia

A

body generally reflects adaptations for sedentary suspension feeding
two shells with a hinge, laterally compressed body
mantle cavity and gills greatly enlarged- gills function in gas exchange and in food acquisition (pull water through for feeding)
foot modified to be burrowing organ and also sometimes drives water across gills by pumping
generally lack head and radula (tend to lack cephalization in general)

75
Q

bivalve feeding

A

water moves through incurrent siphon and then along external aspect of gills, then through gills to interior aspect and out through excurrent siphon
food particles get stuck to mucus on surface of gills and then are moved via cilia towards mouth, where labial palps use mucus to form a bolus (ball of food and mucus) that is ingested

76
Q

bivalve locomotion

A

burrowing

77
Q

burrowing

A

extend foot
expand foot to “anchor” via lateral pressure
contract foot to move body in direction of foot, siphons extend in order to maintain fluid flow through mantle cavity, usually accompanied by opening and closing of shell to loosen sand

78
Q

human impact on bivalves

A

toxins in water poison them then they poison us

invasive species such as zebra mussels are in issue in many water ways

79
Q

problems caused by zebra mussels

A

damage and clog water treatment plants

out compete native species

80
Q

largest of all invertebrate animals

A

Architeuthis, giant squid can get up to 40 feet long

81
Q

class cephalopoda

A

dorso-ventrally elongated
head becomes merged with foot
foot modified to form arms, tentacles, and funnel/siphon used for jet propulsion by taking water into mantle cavity and forcefully expelling
often a reduction or loss of shell

82
Q

adaptations for predation

A 
highly intelligent
well developed eyes
strong swimmers
closed circulatory system
arms, tentacles, and beak for capturing prey
83
Q

eye evolution in molluscs

A

simple eye spots, allow for light detection but that’s it
pigmented cup, allows for light detection as well as determining direction
“pinhole” eye allows for better directional sensitivity and limited image formation, but low-light
primitive lens, allow for slightly better focus and brighter, but no ciliary muscle so can’t alter point of focus
lensed eye allows for focused images and can alter lens or move forward/backward to alter point of focus

84
Q

do cephalopods have blind spots

A

no but have less blood flow to retina

85
Q

chromatophores

A

pigment cells in the skin

can expand and contract to change color

86
Q

what allows cephalopods to change texture

A

papillae

87
Q

cephalopod sex

A

dioecious
internal fertilization
males use a hectocotylus, or hectocotylized arm

88
Q

hectocotylized arm

A

modified arm with pocked for transferring spermatophores

89
Q

can a hectocotylus be detachable

A

may be detachable

useful to deposit sperm and leave before being eaten

Zoology (7 decks)

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