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Zoology > Week 6 > Flashcards

Week 6 Flashcards

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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
odontophore
cartilaginous rod supports radula attachment for muscles
26
radula
protruding, rasping, tongue-like organ | radula teeth made of chitin, constantly replaced (produced posteriorly, used at apex, lost anteriorly)
27
how is feeding modified in some molluscs
bivalves- filter feeders | cephalopods- beak and jaws for seizing prey
28
phylum mollusca | visceral mass- digestive system
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
29
phylum mollusca | visceral mass- circulatory system
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.
30
pericardium
fluid-filled sac, encloses the coelom (and the heart)
31
how does circulation occur
heart pumps blood to body, muscles move blood back to gills
32
what does hemocyanin do
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
33
what color blood does molluscs have
blue
34
phylum molluscs | visceral mass- excretory system
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
35
phylum mollucs | response to stimuli and movement
muscular foot
36
muscular foot
usually ventral attachment or locomotion sometime secrete mucous for adhesion or to help glide on cilia
37
modifications to muscular foot
attachment disc of limpets hatchet foot of bivalves siphon and arms of cephalopods
38
mantle
sheath of tissue on each side of body | forms lobes at outer edge
39
what does the mantle secrete
shell (if there is one)
40
what does the mantle cavity house
gills/lungs
41
what does the exposed mantle surface function in
gaseous exchange
42
what systems empty into mantle cavity and out to environment
excretory and reproductive
43
what does the mantle in aquatic forms usually contain
chemoreceptors
44
what does cilia in mantle cavity do
form water currents to carry waste and reproductive products out and bring in oxygen and, in filter feeding forms, food
45
layers of shell
periostracum prismatic layer nacre
46
periostracum
organic layer or "skin" made of protein, protects underlying layers
47
prismatic layer
protein and calcium carbonate, secreted at mantle edge
48
nacre
mother of pearl, in thin translucent sheets, secreted by epithelium so older parts of shell have thicker layers
49
how is a pearl formed
when something is lodged between mantle and nacre, mantle secretes layers of nacre around it as a defensive mechanism
50
phylum mollusca reproduction
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
veliger stage
has beginnings of foot, shell, and mantle
52
is veliger stage seen in cephalopods
no, they hatch miniature adults
53
class gastropoda critters
snails, slugs, conchs, nudibranchs
54
class bivalvia critters
clams, mussels, oysters, scallops
55
class cephalopoda critters
squids, octopuses, nautiluses, cuttlefishes
56
gastropoda
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
how does gastropoda move
usually through waves of muscular contraction in foot, may be mediated by cilia and/or mucus; tend to be pretty sluggish
58
what do pulmonate land gastropods have
mantle cavity developed into simple lung
59
gastropod quirks
torsion coiling strategies to avoid fouling
60
where is veliger larva mouth and anus
mouth anterior, anus posterior
61
torsion
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
what does putting butt over head do
increases possibility of wastes washing back over gills and mouth (fouling)
63
why does torsion happen
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
did coiling or torsion evolve first
coiling
65
coiling
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
what made the adaptations to avoid fouling happen
loss of gill
67
adaptations to avoid fouling in gastropods
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
how do cone snails eat
with modified hollow barbed radula tooth to stab and inject venom into prey before engulfing it
69
what does conotoxin do
immobilize prey and then harpoon is retracted and prey is eaten
70
can conotoxin be dangerous to humans
yes
71
how is conotoxin useful in medical research
venom in precise and fast acting, allowing quick results with few side effects also contains pain reducing compound
72
snail love darts
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
where does interanal fertilization required to occur in gastropods
to live on land | requires more complicated reproductive system
74
class bivalvia
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
bivalve feeding
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
bivalve locomotion
burrowing
77
burrowing
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
human impact on bivalves
toxins in water poison them then they poison us | invasive species such as zebra mussels are in issue in many water ways
79
problems caused by zebra mussels
damage and clog water treatment plants | out compete native species
80
largest of all invertebrate animals
Architeuthis, giant squid can get up to 40 feet long
81
class cephalopoda
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
adaptations for predation
``` highly intelligent well developed eyes strong swimmers closed circulatory system arms, tentacles, and beak for capturing prey ```
83
eye evolution in molluscs
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
do cephalopods have blind spots
no but have less blood flow to retina
85
chromatophores
pigment cells in the skin | can expand and contract to change color
86
what allows cephalopods to change texture
papillae
87
cephalopod sex
dioecious internal fertilization males use a hectocotylus, or hectocotylized arm
88
hectocotylized arm
modified arm with pocked for transferring spermatophores
89
can a hectocotylus be detachable
may be detachable | useful to deposit sperm and leave before being eaten

Zoology (7 decks)

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