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biol 321 > lecture midterm 2 > Flashcards

lecture midterm 2 Flashcards

1
Q

main characteristics of Phylum Platyhelminthes (7)

A
  • triploblastic
  • cephalization
  • bilateral symmetry
  • acoelomate
  • gut with one opening
  • unsegmented
  • dorsoventrally flattened

— nervous system w cerebral ganglia and two nerve cords
— protonephridia appear

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2
Q

Phylum Platyhelminthes new characteristics:

A
  • nervous system with cerebral ganglia and two nerve cords
  • protonephridia appear
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3
Q

what do protonephridia do for Phylum Platyhelminthes ?

A

help with osmoregulation (maintain salt and water balance)

excretion of ammonia

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4
Q

reproduction: Phylum Platyhelminthes

A

sexual and asexual

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5
Q

body plan (key notes): Phylum Platyhelminthes

A
  • start of cephalization
  • no respiration or circulatory system
    — rely on diffusion
  • cilia for motility
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6
Q

locomotion: Phylum Platyhelminthes

A

by muscular undulations/cilia/mucous

can crawl and swim

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7
Q

feeding: Phylum Platyhelminthes

A

pharyngeal glands secrete digestive enzymes — suck up semi-digested soup

some swallow prey whole

intentional hunting

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8
Q

diagnostic characteristics: Phylum Platyhelminthes

A
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9
Q

new characteristics of Phylum Annelida

A
  • eucoelomate and gut musculature
  • gut with 2 openings (linear digestive tract)
  • metamerism (repeated body plans)
  • blood vascular system (beginning of circulatory system)
  • metanephridia
  • nervous system
    — dorsal brain
    — ganglionated ventral nerve cord
  • chaetae/setae
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10
Q

lost characteristics: Phylum Annelida

A

flattened body plan

protonephridia

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11
Q

reproduction: Phylum Annelida

A

asexually and sexually

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12
Q

functions of coelomic compartments

A
  1. circulation of nutrients and gases
  2. hydrostatic skeleton - enables peristaltic burrowing
  3. role in excretion and osmoregulation (metanephridial systems)
  4. storage of gametes
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13
Q

difference between protonephridia and metanephridia

A

protonephridia :
- excretory tube without an internal opening
found in platyhelminthes and rotifers
— helps in osmoregulation with cilia creating pressure to move waste/excess metabolites from the animal

metanephridia :
- open to the body cavity and attached to duct that opens to exterior
found in annelids
— more efficient than protonephridia
— selective reabsorption is performed in the cells lining metanephridium

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14
Q

lost characteristics: Phylum Annelida

A

flattened body plan

protonephridia

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15
Q

locomotion: Phylum Annelida

A

peristaltic

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16
Q

Errantia vs Sedentaria

A

groups of annelids

Errantia : eversible pharynx w jaws

Sedentaria : eversible pharynx never armed w jaws

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17
Q

general

A
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18
Q

general characteristics of all lophotrochozoans

A
  • true tissues
  • bilaterial
  • triploblastic
  • protostome embryos
  • either eucoelomate or pseudocoelomate
  • extracellular digestion
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19
Q

Phylum Nemertea ‘Ribbon worms’ diagnostic feature

A

proboscis apparatus - hydrostatically eversible

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20
Q

characteristics: Phylum Nemertea ‘Ribbon worms’

A
  • eucoelomate
  • circulatory system w ciliated lateral blood vessels derived from mesoderm, brain and nervous system
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21
Q

reproduction: Phylum Nemertea ‘Ribbon worms’

A
  • dioecious (2 sexes , not hermaphroditic)
  • temporary gonads (transient gonads) — developing only when ova and sperm are ready
  • free swimming larva
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22
Q

locomotion: Phylum Nemertea ‘Ribbon worms’

A

ciliated epidermis

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23
Q

feeding: Phylum Nemertea ‘Ribbon worms’

A

predatory - w thin proboscis apparatus, some species pierce & inject neurotoxin

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24
Q

lost characteristics: Phylum Nemertea ‘Ribbon worms’

A

chaetae/setae, metamerism (segmentation)

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25
Q

new characteristics: Phylum Rotifera

A
  • eutly (fixed number of cells)
    — develop by cell division until maturity then only cell growth
  • have lorica (shell-like protective outer covering)
  • reinforced with sand grains
  • closed at one end
  • protonephridia
  • colonial
  • small cerebral ganglion
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26
Q

distinct characteristics: Phylum Rotifera

A
  • ciliated corona (for suspension feeding)
  • mictic reproduction (stressed cycle)
  • cryptobiosis
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27
Q

what is cryptobiosis

A

helps rotifers and other species survive in fresh water

in one of their reproductive stages they can enter into this

essentially like a death state, can dry up completely, metabolism shuts down, can last for years, decades, or even up to a century — can recover in as little as 10 minutes when water is added

this makes them industrially useful - used to feed other organisms

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28
Q

locomotion: Phylum Rotifera

A

can be sessile or free swimming by movable ‘scales’ - can swim well

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29
Q

feeding: Phylum Rotifera

A

ciliated corona (suspension feeding)

predatory in some species

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30
Q

reproduction: Phylum Rotifera

A

sexually (mictic and amictic)

31
Q

Phylum Mollusca characteristics:

A

dont have one trait that consistently runs thru all molluscs bc of such diversity

look for 4 things: (basic body plan of molluscs)
shell, mantle, foot, gills

32
Q

2 major subphyla of Phylum Mollusca

A

Conchifera: all shell bearing molluscs

Aculifera: no SOLID shell, only spicule or sclerite bearing

33
Q

Phylum Mollusca: Polyplacophorans (Chitons)

characteristics

A
  • calcium carbonate shell w 8 pieces and shell valves
  • ciliated gills (ctenidia)
  • osphradia (sensory organs)
  • mantle cavity
  • shell attached muscles
  • radula
  • pericardium and gonads
  • circulatory system w heart and dorsal blood vessel but then it is open
34
Q

Phylum Mollusca: Polyplacophorans (Chitons)

body plan

A
  • head
  • visceral mass
  • muscular foot (hydrostatic)
  • mantle (pallium)
  • gills (ciliated ctenidia)
35
Q

Phylum Mollusca: Polyplacophorans (Chitons)

key notes on body plan:

A
  • radula
  • well developed digestive system
36
Q

Phylum Mollusca: Polyplacophorans (Chitons)

diagnostic characteristics:

A

radula and shell valves

37
Q

Phylum Mollusca: Polyplacophorans (Chitons)

locomotion:

A

slow moving

never detached from substrate

38
Q

body regions of molluscs

A

visceropallium:
all collective dorsal parts (includes body organs and shell)

cephalopodium:
all collective ventral parts (includes head -mostly mouth- and foot)

39
Q

Phylum Mollusca: Polyplacophorans (Chitons)

feeding:

A

radula w magnetite teeth (rasping and feeding)

ctenidia - cilia create water flow to increase ability to take gases out of water

40
Q

Phylum Mollusca: Polyplacophorans (Chitons)

reproduction:

A

broadcast sperm and females retain eggs and then they are fertilized

41
Q

water flow in Chitons (polyplacophorans)

A

from head w mouth to anus

anterior to posterior
— from ciliated water flow

clears waste — exhausted near the anus but not thru the anus

runs past paired osphradia (sensory) - olfactory or chemosensory epithelian areas near gills

42
Q

Phylum Mollusca: Polyplacophorans (Chitons)

radular teeth

A

diagnostic trait

magnetite (Fe3O4 : loadstone) makes radular teeth very hard for scraping rock substrates

can bind these minerals to teeth to make them harder - 3 fold harder than human enamel

shows up on rocks in “fan pattern”

43
Q

Phylum Mollusca: Polyplacophorans (Chitons)

nervous system:

A

basic nerve plan for molluscs

  • related to annelids
    — 2 pedal nerve cords then split into 2 areas - these 2 areas correspond to 2 body areas (visceropallium and cephalopodium)

pedal nerve cords on bottom (cephalopodium)

visceropallium nerve cords on top

ring of nerve tracks that surround pharynx

BRAIN SURROUNDS ESOPHAGUS

44
Q

coelom vs hemocoel

A

coelom - principal body cavity in annelids, echinoderms, and chordates
- fully lined w mesothelium

hemocoel - principal body cavity in arthropods and molluscs (not annelids) - with reduced form of coelom

BOTH: structures filled w fluid and act as cushion or hydrostatic skeleton, protecting organs

45
Q

Phylum Mollusca: Polyplacophorans (Chitons)

circulatory system:

A

Pericardium space with muscular heart is confined to just the posterior end

Blood goes anteriorly via dorsal blood vessel

Blood enters the connective tissue spaces directly, surrounding the organs in the hemocoel

Blood percolates eventually into the afferent blood vessel of the ctenidia, and is then returned to the heart

circulation looles familiar - heart in same position - no ventral blood vessel (not returning in single vessel be the blood is coming back thru the coelomic space = hemocoel
- blood entering connective tissue space directly that are surrounding organs - eventually comes back thru other vessel and denidia then back to heart

46
Q

Phylum Mollusca: Polyplacophorans (Chitons)

digestion:

A

Digestive glands (pair)
secrete digestive
enzymes and store lipid energy

Anterior has characteristic radula, formed in deep invagination ventral to buccal cavity, secretes ribbon of teeth

now we see radula
- vegetative matter that the mollusc consumes

  • posterior side to the right
  • head here is just mouth in polyplacophorans

radula = constantly regenerated - teeth in radula sac
-to provide grinding motion

sac is secreting hard radula
- represents feature that we didnt have in annelids at all

Present in all extant molluscs except bivalves

47
Q

Phylum Mollusca: Polyplacophorans (Chitons)

visual apparatus:

A

light sensing thru multiple lenses and openings on the back — called ocelli

can detect movement and shapes

made of CaCO3

Essential for sensing light regimes, hence nocturnal behavior patterns
— need to know when light and dark for feeding

48
Q

Phylum Mollusca: Gastropoda

new characteristics

A
  • shell as protective retreat — long coiled cone (chitinous operculum - hard door that seals them in)
  • torsion in body plan (both internally and externally)
  • development of head with tentacles and eye spots
49
Q

Phylum Mollusca: Gastropoda

lost characteristic:

A

bilateral symmetry

50
Q

Phylum Mollusca: Gastropoda

body plan key notes:

A
  • downside of torsion is fouling of ctenidia — solved by loss of right ctenidium
  • shift of anus to right side
  • osphridium to left and oblique current over ctenidium through mantle cavity and out hole vent in shell
51
Q

Phylum Mollusca: Gastropoda

diagnostic characteristic:

A

torsion - (twisted shape, not elongated like Poly- and Monoplacophorans, cephalopodium 180o from visceropallium, mantle cavity over back of head, anus opens into anterior mantle pocket, gill(s) in this anterior cavity)

evidence = cross-over of visceropallial nerve cords

52
Q

Phylum Mollusca: Gastropoda

conservation biology:

A

scaly-foot or volcano snail - A remarkable deepsea gastropod, with metallic armour and symbiotic feeding
— just discovered and already under conservation
— International conservation bodies are largely ineffective against national policies
— Depth is no refuge from anthropogenic impact

queen conch - as they get older and reach maturity, this is when highest reproductive output. conservation and current policies only for length but should be for shell thickness at flare

abalone - density matters, if not enough wont support the population due to being broadcast spawners — population continues to fail even after stopping fishing bc of alee effect
— positive correlation between population size or density and the mean individual fitness of a population or species, usually at low populations
—POSSIBLE CAUSES OF REPRODUCTIVE FAILURE:
- Fertilization failure due to spawning distance
- Poorly provisioned trocophore larvae (malnutrition)
- Competition with other benthic organisms, and starvation
- Environmental stress

53
Q

Phylum Mollusca: Gastropoda

feeding:

A

radula, proboscis is everted for grazing, moon snails drill into bivalves and eat them, cone snails use conotoxins, injected via proboscis to stab fish and immobilize them

54
Q

Phylum Mollusca: Gastropoda

reproduction:

A

internal sexual reproduction

55
Q

heterobranchia

A
56
Q

Phylum Mollusca: Bivalves

new characteristics:

A
  • new muscle arrangements for shell contraction – adductor muscle
  • evolution of hinge on bivalve shell
  • muscular arrangements for burrowing
  • shell secretion system
  • compared to polyplacophorans these are now bent over to close up (example of evolutionary change)
  • Enlarged singular muscle here where in polyplacophorans there were 8 pairs of muscles
57
Q

Phylum Mollusca: Bivalves

lost characteristics:

A

NO radula

laterally compressed body (opposed to horizontally)

58
Q

Phylum Mollusca: Bivalves

why are they how they are:

A

shell hinges (ligaments) keep it open, muscles close it

59
Q

Phylum Mollusca: Bivalves

key notes on body plans:

A
  • laterally compressed body (opposed to horizontally)
  • deep mantle cavity
  • single pair of ctenidia
  • new muscle for shell contraction (adductor muscle)
  • dorsal hinge for shell open and close
  • retaining nerve ring and dual cord structure but minimal external cephalization

—In many species: dual siphons (incurrent and excurrent siphon)

60
Q

Phylum Mollusca: Bivalves

diagnostic characteristics:

A
  • adductor muscle
  • could also be dorsal hinge
  • NO radula
61
Q

Phylum Mollusca: Bivalves

conservation biology:

A

heat dome effects show drying out from osmotic stress or desiccation, leading to death (not snapping back like when cooked)

62
Q

Phylum Mollusca: Bivalves

locomotion:

A

burrowers – deep and shallow, digging action w foot, 1. expansion of foot terminus creates anchor, 2. contraction of adductor muscle closes shell, 3. contraction of dorso-ventral muscles pulls animal down into substrate

Mussels – byssal threads hold onto substrate on exposed intertidal rocky shore

63
Q

Phylum Mollusca: Bivalves

feeding:

A

protobranchia = deposit feeding – using ciliated palp tentacles, each tentacle has a ciliated groove carrying particles back to mouth

autobranchia = suspension/filter feeding – ctenidium used for gas exchange AND suspension feeding –> lateral cilia create water current, laterofrontal cilia intercept particles, frontal cilia carry particles down filament

64
Q

Phylum Mollusca: Bivalves

defense:

A

hinge ligament very important – main defense mechanism bc it will snap shut when released from stretching

65
Q

Phylum Mollusca: Bivalves

alternative lifestyles and feeding modes:

A

wood borers, septibranchia, fish parasites

66
Q

Phylum Bryozoa

new characteristics:

A
  • zooecium (exoskeleton or ‘house’)
  • operculum (protective door)
  • U-shaped digestive tract
  • 2 coelomic compartments (lophophoral coelom and perivisceral coelom)
67
Q

Phylum Bryozoa

lost characteristics:

A

no specialized organs (backtracking away from molluscs)

68
Q

Phylum Bryozoa

why are they how they are:

A

colonial bc polymorphism – non-feeding non-reproductive zooid for defense purposes only = avicularium (large operculum and strong muscles, no digestive tract)

  • brown bodies = not able to excrete accumulated metabolic waste so cells of the gut become storage spots for waste –> brown bodies where older zooids undergo senescence – defecate brown body and regenerate itself using stem cells – brown body ejected out
69
Q

Phylum Bryozoa

key notes on body plans:

A

zooecium = exoskeleton (doesn’t join up which allows for passing of nutrients and for specialization)

operculum = protective door (different structure than what we’ve seen before but same function)

mesothelium

lophophore and lophophore retractor muscles

U-shaped gut (anus ejecting waste thru lophophoral sheath when tentacles extended)

anus outside of exoskeleton when tentacles are extended

70
Q

Phylum Bryozoa

diagnostic characteristics:

A
  1. zooecium (house) exoskeleton – often calcified
  2. lophophoral coelom (comprised of the hollow tentacles
71
Q

Phylum Bryozoa

locomotion:

A

colonial

sessil

72
Q

Phylum Bryozoa

Feeding:

A

suspension feeders – lophophore (funnel w ciliated tentacles, goes up and brings stuff back in)

73
Q

Phylum Bryozoa

Reproduction:

A

sexual and asexual, typically sequential androgynous hermaphrodites (male first then switch to female)

broadcast spawners - most are “spermcasters” (only sperm released, eggs retained)

sperm released thru pores in tentacular lophophoral coelom (tentacles filled w ciliated mesoderm)

then ends w free-swimming ciliated larvae

Note: this reproductive approach important for growing and expanding colonies

74
Q

Phylum Bryozoa

Defensive strategies:

A

heterozooids (e.g. avicularia & vibracula)

colonialism (defense against partial predation)

calcification of frontal membrane (requires ascus) - hydrostatic ball w muscles can send out for defense

biol 321 (7 decks)

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