BIOL 321 Part II Flashcards
Bryozoa lifestyle
colonial, sessile, suspension feeders
Individual bryozoan
zooid
very tiny (mm’s)
lophophore
lophophore
funnel of ciliated tentacles used for suspension feeding
Bryozoan exoskeleton
zooecium
often calcified
Bryozoan digestion
u-shaped digestive tract
why is u-shaped digestive tract appropriate for exoskeleton enclosed organisms
if posterior end is closed feces would accumulate
Bryozoan compartments
2 coelomic compartments - lophophoral coelom, perivivsceral coelom
Bryozoan organs
no specialized organs for gas exchange, excretion/osmoregulation, internal fluid circulation
How do Bryozoans accomplish gas exchange/fluid circulation without organs
ciliated mesothelium circulate fluids/gases
Bryozoan colony form diversity
stoloniferous
encrusting
erect
encrusting bryozoan colonies
zooids lie flat on substrate w/ dorsal surface attached to substrate
stoloniferous bryozoan colony
creep over rocks, zooids bud up from stolon
erect Bryozoans
flat blades
branched fronds
solitary bryzoan
Monobryozoan
solitary, motile, infaunal- interstitial fluids of sand grains, extensions hold on to sand grains, contact to pull organism down
Bryozoan polymorphs
heterozooid
autozooid
Heterozooid
usually defensive, non-feeding
e.g. avicularium, operculum snaps shut to deter predators/organisms settling
Autozooid
feeding, reproducing
Vibraculum
type of heterozooid (Bryozoan)
elongate ‘whips’ swarm around colony, dislodge settling/predators/used as ‘legs’ for movement
Bryozoan reproduction
larva -settles -metamorphosis -initial zooid (founder)- aseuxal budding - more individuals = colony
sexual reproduction to form new colony
Bryozoan circular colony
founder cell in middle
budding takes place around circumference
periphery of encrusting bryozoan colony
budding zone
brown body
degenerated mass of zooid tissue, only epidermis +mesothelium, regressed zooid
what happens with brown body
regenerate whole new zooid w/ brown body in stomach - defacate it out
why do zooids regress and regenerate?
possibly method of dealing with toxin/waste build up
Bryozoan defense
heterozooids colonialism chemical defense induced defences calcification of frontal membrane
colonial defense
strength in numbers, genome maintained - unlikely predator will eat whole colony, can regenerate
what are chemical defenses
secondary metabolites
deter predators
antibiotics
Bryozoan secondary metabolites
bryostatin - appears to have anti-cancer, anti-alzheimer properties, synthesized by symbiotic bacteria
why is it important to calcify frontal membrane of Bryozoan
flexible frontal membrane leaves them vulnerable to predation
e.g. nudibranch slices frontal membrane w/ radulae and sucks out bryozoan
Induced defense, bryozoa
initially put all E into reproduction, predator comes, w/i 48hrs of predator feeding zooids form calcareous spines on corners of zooecia
Bryozoan frontal membrane calcification
frontal surface inflexible to protect against predators
how can lophophore retreat with inflexible frontal membrane
sac inside of perivisceral compartment is filled w/ fluid, ejects fluid out pore to make room for lophophore
periversceral fluid-containing sac in Bryozoans with frontal membrane calcification
Ascus
how is lophophore moved out in Bryozoan w/ frontal membrane calcification
parietal muscles expand balloon and water is sucked back in - forces lophophore out of way
how is lophophore retracted in a Bryozoan
lophophore retractor muscles
Bryozoan sexual characteristics
gametes arise from mesothelium
hermaphroditic (sequential or simultaneous)
sperm spawn through tentacular pores
external or internal fertilization
Bryozoan external fertilization
both gametes spawned externally
long-lived feeding larvae
Bryozoan internal fertilization
eggs maintained internally, brooded for short period, short-lived non-feeding larvae
Bryozoan egg brooder
ovicell (heterozooid)
Mollusca subphyla
Conchifera
Aculifera
Aculifera groups
Polyplacophora
also Chaetodermomorpha, Neomeniomorpha which we are not studying and are placaphora
Conchifera groups
Monoplacophora Cephalopoda s.g. Scaphopoda s.g. Bivalvia s.g. Gastropoda
Mollusca primitive characteristics
dorso-ventral differentiation
CaCO3 shell
mantle cavity, gills, osphradia
shell-attached muscles
chiton shell
8 articulating shell valves w/ 8-pairs dorsal ventral shell-attached muscles (from shell-foot)
Mollusc dorso-ventral differentiation
visceropallium
cephalopodium
Chiton osphradia
2 sensory organs - on either side of anus
Mollusca gill
ctenidium - central axis w/ gill lamella, afferent/efferent blood vessels
Mollusca circulation
hemal fluid in to afferent blood vessel, through each gill lameli, out efferent blood vessel
Mollusca water circulation
in between each lameli - countercurrent to hemal flow to maximize efficiency of gas exchange
Mollusca reduced coelom
pericardium
containing heart, attached to metanephridia, gonads, associated with gut
metanephridia, Mollusca
heart contraction = ultrafiltration
fluid down metanephridial ducts = selective reabsorption
Mollusca gonads
derived from mesothelium
most extant organisms do not retain connection between gonad-pericardium
Mollusca digestion
mouth, radular cartilage, foregut, radular sac
radular sac
secretes riot of radular chitinous teeth on ribbon
radular cartilage
rods, support radular teeth
how radula works
muscle protrudes radular cartilages out of mouth carrying radular teeth - pull teeth back in scraping substrate
Mollusc radula + cartilages
buccal mass
Mollusc nervous system
circum-esophogeal nerve ring (cephalopodium) visceropallial nerve cords pedal nerve cords pleurovisercal ganglia cerebral ganglia pedal ganglia
distinctive characteristics of chitons
minimal cephalization dorso-ventral flattening dorsal shell w/ 8 articulating valves mantle assisted substrate adhesion radula with magnetite caps
Chiton cephalization
non-ganglionated
non-active, head non-specialized
Why chitons have dorsoventral flattening
low profile helps avoid being washed away - adaptation to wave swept shores
Chiton substrate adhesion
very muscular foot + mantle periphery for clinging
lift mantle roof = negative pressure = suction
Chiton radula caps
Mollusc teeth are replaced but chitons cap w/ magnetite (Fe containing bxomineral) to reduce wear
Chiton reproduction
dioecious, broadcast spawn (m and f), external fertilization, gametes from gonad mesothelium, ciliated non-feeding larvae
largest metazoan phyla
Arthropoda
2nd largest metazoan phyla
Mollusca
Class Monoplacophora
very rare, deep sea, only known from fossils, single dorsal shell, ventrally similar to chiton, sister clade to rest of conchifera
Monoplacophora ventral
mouth, anus, lateral mantle cavity w/ ctenidia, 8 dorsal shell muscles
Gastropod shell
isometric coiling -coils in same plane, only see one from front view -asymmetric coiling
Accommodating coiled shell, gastropod
visceroplallial elongation and coiling
gastropod shell central pillar
columella, CaCO3, central coiling axis
shells are designed to be
protective retreat
gastropod shell-attached muscles
single or single paired
hold on to columella
run down to foot/head to pull head in, close operculum
changes from monoplacophoran to hypothetical intermediate gastropod
Shell coils (exogastric) and elongate dorsoventrally, reduced shell aperture, mantle cavity, # shell muscles, #ctenidia
changes from hypothetical intermediate gastropod to derived gastropod
Torsion (180ºrotation) of visceropallium relative to cephalopodium, rotation of shell (endogastric shell coil)- anus + mantle cavity over mouth
evidence of torsion
anatomy of living gastropod
development of basal gastropod
asymmetries in gastropods
- asymmetric coil of shell (goes to the left or right)
- torsion
- non-bilateral organs/structures (majority of gastropods have left ctenidium/osphradium)
extant gastropod anatomy as evidence of torsion
cross-over of visceropallial nerve connectives
gastropod veliger larva
tiny calcareous shell swimming side down, 2 velar lobes, modified trochophore (prototroch, metatroch for feeding)
torsion advantages
mantle cavity and therefore ctenidia are moved anterior - water that is brought in is less disturbed by movement
torsion advantage to developing gastropod
mc below foot = pull foot in first, velum in last; velum is more valuable and vulnerable than foot, advantageous to have mc above head and pull foot in last
development of basal gastropod as evidence of torsion
ontogenetic torsion
see foot on both sides of shell in developmental stage
torsion hypothesis test, abelone
1 batch pre-torsional larvae, 1 post-torsional; both have predators; found no difference in # survivors- no evidence of torsion being advantageous
1 problem of torsion
results in deeper anterior mantle cavity - water needs to be frequently circulated for aeration and removing waste
solutions to fouling
restricted mantle cavity
shell perforations
shit of anus to right side
all gastropods with shell perforations
have 2 ctenidia
shifted anus, gastropod
Majority of gastropods; loss of right ctenidium, osphradium;
shift anus to right;
oblique current through mantle cavity; pick up fecal material last on way out
gastropod snorkle
siphon
right side, highly mobile, muscular, samples water and picks up chemical signatures
alternative hypothesis for gastropod body
unilateral enlargement of mantle cavity- 2 mc’s and one expands in different ways
types of gastropod MC enlargement methods
monotocardian
diotocardia
heterobranchia
monotocardian
enlarged MC, ctenidia on left, anus on right
diotocardian
enlarged MC, 2 ctenidia (L/R), anus in middle
heterobranchia
MC not enlarged, reduced to 1 ctenidia
gastropod cephalization
fast moving, A-P axis = need for receptors, ganglionization: 1+ tentacle sets, eye spots, series of ganglia
Class Gastropoda main features
protective shell - single plate into coiled cone
torsion
pronounced development of head
Class Gastropoda groups
Patellogastropoda s.g.
Vetigastropoda s.g.
Caenogastropoda s.g.
Heterobranchia
Old Class Gastropoda phylogeny
Prosobranchia (Patellogastropoda, Vetigastropoda, Caenogastropoda) s.g. Opisthobranchia (Heterobranchia) s.g. Pulmonata (Heterobranchia)
Vetigastropoda
keyhole limpets, abelone
Caenogastropoda
majority of marine gastropods, well developed shells
Gastropoda primitive feeding method
herbivorous grazing using radula
radula
ribbon of teeth secreted by radular sac, protruded out of mouth to scrape rock
buccal cavity
area of gut that radula opens in to
vetigastropod feeding
many herbivorous grazers, retain primitive method
Caenogastropod feeding
many herbivorous grazers, retained primitive feeding method (radula); many predators with proboscis
Proboscis
right side, normally tucked in, used for feeding
herbivorous gastropod foregut
mouth - buccal cavity- anterior esophagus- mid-esophageal gland; salivary glands attach to buccal cavity
predatory gastropod foregut
deep in-pocket in anterior end = proboscis sac, buccal cavity = proboscis, esophagus greatly lengthened, mid-esophageal gland is enlarged and connected to esophagus by narrow gut
evidence of predatory gastropods
shell drills, leave bevelled edged hole on preys shell
how predatory gastropod makes shell drills
tip of proboscis has accessory boring organ - raps on shell = mechanical abrasion; also chelate shell = chemical dissolution
Cone snail
highly derived gastropod feeding, mostly tropical/subtropical, predatory caenogastropod, feeds on worms/molluscs/fish
Cone snail feeding
very long proboscis, w/ harpoon tooth and venom
cone snail harpoon tooth
apex of radular tooth is shaped like hollow harpoon, snail takes 1 tooth and places it at end of proboscis, tooth is connected to venom gland
cone snail venom gland
midesophogeal gland highly elongated ending in muscular ball specialized to synthesize and secrete conotoxins
conotoxin
neurotoxins, peptide that bind to Fe channels and neurotransmitters, rapidly immobilize prey, any 1 species may have 100’s
Heterobranchs
elaborated dorsal surface, secondarily deflected anus to posterior end (detorsion); loss of larval shell during metamorphosis
Heterobranch loss of shell
do have shell in juvenile form (and torsion), crawl out of shell and discard it and operculum
Heterobranch defense
chemical defense
escape behaviour
sequester nematocysts
autotomy
chemical defense, Heterobranch
dorsal chemical glands - unpallatable/toxic
where do Heterobranchs get chemical defense
some make own
many steal from prey (sponges, bryozoans) and put in dorsal gland sacs (cerata/papillae)
escape behaviour, heterobranch
touched by predator – lift off seafloor - d/v body undulations - catch current and float away
sequestering nematocysts, Heterobranchia
feed on cnidarian- sequester nematocyst- carried up to cerata and deposited- phagocitized - utilized
where are nematocysts stored in heterobranch
cnidosac - special sac at time of cerata lined by epithelium
how are heterobranchs able to utilize nematocysts?
secrete mucus that makes them not trigger (like clown fish) - may get stung at first until they learn the right formula (species specific)
Nudibranch autotomy
rapidly release body part, mainly cerata
terrestrial heterobranchs
snails, slugs; terrestrial; threats include desiccation, T changes
terrestrial heterobranch, breathing
closed mantle cavity = ‘lung’, pneumostome = pore, opening to lung (able to close)
adaptations for life on land (Heterobranchia
mantle cavity forms internalized lung
conversion of ammonia to uric acid
asetivation
Aestivation, heterobranchs
metabolic slow-down, hide in humid location,
tolerance of desiccation
ability to rapidly rehydrate
freshwater snail w/ air breathing adaptation
Caenogastropods, pneumostome + long siphon opening in to lung
(convergence w/ heterobranchs)
how gastropods can rehydrate
open spaces between epithelial cells
Vetigastropoda reproduction
broadcast spawn gametes, external fertilization
Caenogastropoda, Heterobranchia reproduction
internal fertilization, encapsulated eggs, juvenile crawls out of egg capsule
Class Bivalvia
dv flattened body 2 shell valves spacious lateral mantle cavity to house ctenidia minimal cephalization no radula
Bivalve falttening
including foot, facilitate digging
why bivalves need 2 valves
life in substrate - need to remain open for circulation, need to shells to remain open - pressure would collapse mantle
Bivalve radula
none in extant members, feeding by suspension or deposit
bivalve water flow
along edge of shell or restricted to siphons
bivalve adductor muscles
pull valves together, cause tension in ligaments, when released ligaments pull shells open
Bivalve shell secretion
secreted by outer mantle lobe, sequential layers of bxomineral CaCO3 w/ crystals oriented in opposite directions - cross-hatched for strength
Bivalve mantle margin
sensory structures on periphery of mantle fold (middle lobe)
bivalve middle lobe
most exposed to environment, may contain photoreceptors, tentacles
bivalve outer lobe
secretes shell
bivalve inner lobe of mantle fold
‘muscle lobe’
has pallial muscles connected to shell valve to pull and tuck all soft tissues in side shells
Diversity of feeding in Bivalvia
prosobranch
lamellibranch
septibranch
Protobranchs
deposit feeder; use palp tentacles; gills for gas exchange only, ancestral feeding strategy, long paired siphons
palp tentacles
ciliated, deposit feeding in protobranchs
Protobranch ctenidium
gas exchange only
non-elaborate gill filaments on sides of gill axis
Lamellibranch
ctenidia for gas exchange and feeding, suspension feeders
lamellibranch ctenidia
elongate filaments, folded back to fit, highly ciliated to carry particles
lamellibranch folds
demibranchs
outer demibranch = closest to shell
Lamellibranch cilia
each ‘limb’ is surrounded by 3 types of cilia: lateral cilia, laterofrontal cilia, frontal cilia
lateral cilia, lamellibranch
short, on the ‘top/bottom’, create water current
laterofrontal cilia, lamellibranch
longer, point diagonally, intercept particles
Septibranch feeding
rare, predators, suction feeding, enormous inhalant siphon used for sucking in small organisms
septibranch ctenidia
modified gill = muscular, perforated diaphragm; closed shell, elevated muscular shelf = increased volume in inhalent chamber = suction
Bivalvia habitatlifestyle diversity
burrowers (majority; deeper = longer siphon)
attached to solid substrate
boring
example of shallow burrowing bivalve
cockle
e.g. of bivalve attached to solid substrate
mussels
Mussel attachment
secrete byssal threads
frontal cilia, lamellibranch
short, face out, frontal surface, carry particles down filament to elbow-like area of gil filament
example of deep burrowing bivalve
geoduck
how to use byssal threads
byssal gland by foot secretes fluid– fluid runs down foot, forms puddle– starts to harden - lift foot- move foot and repeat
oyster substrate attachment
cement w/ CaCO3
boring bivalve
shipworms
free-swimming larva, settle, metamorphose, feed/create tunnel
Class Scaphopoda
tusk shells, see text book ch 12
Class Cephalopoda
active, pelagic, predatory, smartest, largest, fastest molluscs, 3 subclasses, 1 extinct
Cephalopod molluscan characteristics
radula
molluscan-style gill (but not ciliated)
shell-secreting mantle (but reduced/lost in most extant)
Cephalopod unique characteristics
septate shell
highly modified foot
Cephalopod foot modifications
prehensile appendage (arms, tentacles) funnel
Cephalopoda groups
Nautiloidea - extant, since Palaeozoic, first known group (540Ma)
Ammonoidea - extinct end of Mesozoic, known from mid Paleo
Coleoidea - extant, known from end of Paleo
Nautilus
primitive cephalopod, tentacles have no suckers, external shell, hood, funnel
Nautilus shell
external, gas-filled chambers, chambers separated by septa, septa perforated for siphuncle
Squid
active, agile swimming, predatory feeding
squid example
Loligo
squid predation
visual predators- image-forming eyes, eye morphology convergent w/ vertebrates
Coleoidea metabolics
high metabolic rate, ventilate gills by pumping muscular mantle, closed circulatory system, systemic and branchial hearts
Coleoid branchial hearts
booster pumps to force blood through gills
Protostomia groups
Lophotrochozoa
Exdysozoa
Exdysozoan groups
Nematoda, Onychophoran, Arthropoda
Ecydsozoa shared morphological characteristics
Ecdysis
no motile cilia/flagella
Ecdysis, ecdysozoa
periodically moult exoskeleton/cuticle for growth
Phylum Nematoda basic characters
multilayered collagenous cuticle, 4 moults, longitudinal muscles only, pseudocoel, syncytial epidermis, anterior nerve ring, longitudinal cords, aberrant cilia, eutely
Nematode cilia
non motile, restricted to sensory function
eutely
embryo hatches w/ set # of somatic cells and never produces any more; growth only by enlargement of cells
Nematode body movement
thrashing motion; dorsoventral contractions; only useful for forward motion in dense medium
Needed for nematode locomotion
stiff cuticle;
fluid maintained under high pressure in pseudocoel;
longitudinal muscles
Nematode feeding
triradiated pharynx, muscle contraction opens lumen, have to actively open gut by muscular means b/c high pressure of gut, must drink water to actively push food down
Nematode reproduction
Asexual and sexual
nematode asexual reproduction
very rare - parthenogenesis (no budding or fission)
nematode sexual reproduction
dioecious, internal fertilization, males w/ copulatory spicules, ameboid sperm (aflagellate)
nematode developments
4 moults to adult stage; egg - 4 juveniles - adult; eutely
Dauer larva
Nematode facultative diapause, triggered by enviro. cues, age arrest (reduced metabolic rate), occurs at L2 (juvenile #2)
parasitic nematode examples
hookworm, wuchereria, golden nematode
Hookworm
intestinal parasite, 1 host, cuticle around mouth forms tooth/hook-like projections, consume blood from intestinal wounds, leads to anemia
Hookworm life cycle
adult worm in human intestine - eggs passed in feces - juv. 1 hatches - 2 moults - juv. 3 burrows into skin, often foot - moves to circulatory system - heart - lungs - trachea - pharynx– intestine
Wuchereria bancrofti
Nematode, Elephatiasis, microfilariae larvae clog lymphatic vessels, causes grotesque swelling, 2 hosts - human, mosquito
Wuchereria bancrofti life cycle
microfilariae - mosquito - moult - move to salivary gland - transmitted to human
Golden nematode
1 host, damaging potato parasite, cysts on roots are dead swollen fm bodies filled w/ eggs
Golden nematode distribution
Europe, Asia, Africa, Canada (Nfld, Central Saanich)
What golden nematode does
burrow in to roots, feed on root tissues, cause death/stunted growth
Caenorhabditis elegans
model organism for developmental genetics- tiny (few mm’s), short generation times (3days), hermaphroditic (self-fertilize), eutely (959 somatic cells)
why C elegans is a model organism
cell lineage known for all cells - map
synaptic connections btw neurons mapped
entire genome sequenced
ratio of animals that are arthropods
4/5
Phylum Arthropoda importance
high successful by any metric important food web component medical importance economic importance model organisms
Arthropods success
most specious, most individuals, ability to invade almost all habitats, etc.
Arthropods in food webs
important component - 1º and 2º consumers, removal of arthropods would collapse any ecosystem
e.g. Arthropod medical importance
mosquitos are disease vector
e.g. Arthropod economic importance
positive and negative
pollination, crop destruction
Arthropod phylogenetic controversies
monophyletic or polyphyletic?
sister groups?
relations amongst major groups?
one of the most extensively debated subjects in evolutionary biology
Arthropod metamerism
convergent with Annelida
consolidations of multiple adjacent metameres into coherent morphological units with specialized functions
tagmosis
unit = tagmata
Arthropod exoskeleton
chitin (polysaccharide) + crosslinked proteins (sclerotization) secreted by epidermal epithelium
Arthropod exoskeleton functions
support
protection (predators, mechanical abrasion)
facilities movement
exoskeleton movement function
transmits force of muscle contraction
Parts of arthropod exoskeleton
epicuticle (lipids, waxes)
Protocuticle (exocuticle + endocuticle)
Epidermis
axial arthropod skeleton
4 hardened plates (sclerites): top = term, bottom = sternum, sides = pleuron
appendicular arthropod skeleton
articles - thin hollow tubes connected to form appendages
arthropod jointed appendages
joints formed by thin, flexible exoskeleton (articular membrane)
movement of arthropod appendages
antagonistic muscle bands
condyle
many appendages/articles
Arthropod antagonistic muscles
extensor and flexor muscles
condyle
one article fits precisely into the other - only permits movement in 1 direction
Benefit of many articles in arthropod appendages
movement in different directions/planes = large range of motion
Adaptive potential of arthropod appendages
versatile raw material:
- can be sculpted into diff. shapes/functions
- each article can be precisely moved by muscles
exoskeleton tools
sensory, mouthparts, prey capture, crawling, swimming, escape behaviour
arthropod secondary body compartment
hemocoel separated by diaphragm in to pericardial and peravisceral
Arthropod nephridium
epithelial tubes capped by epithelial sac = metanephridium
excretory tubes homologous to metanephridium
saccule homologous to shrunken coelom(?)
extra consequences of exoskeleton
moulting
sensilla
Arthropod growth
periodic moults under hormonal control- secrete inactive chitinases
moulting process, cellular
glandular cells secrete inactive chitinase (proenzyme) - new epicuticle secreted - proenzyme activated - digest endocuticle - split out at areas of weakness
new exoskeleton
week/soft, not cross linked - pump up with air/water -make bigger before hardening - harden - shrink back down - have room
sensilla
sensory, ball and socket joint, neurons w/ dendrites, lower exoskeleton cover
What is Arthropod sister group
Onychophora
Phylum Onychophora
velvet worm, low species #s compared w/ arthro. (180), very humid terrestrial, chitinous cuticle, metameric, non-jointed appendages, annelid/arthropod, distinct terminal ends (claws)
earliest known Arthropod
Hallucigenia, Burgess Shale, Field BC, early Cambrian
Arthropoda subphyla
Trilobitomorpha
Chelicerata
Mandibulata
Chelicerate tagmata
2 tagmata
Prosoma
Opisthosoma
Chelicerate # of appendages
Prosoma - 6 pr.
Opisthosoma - variable
Chelicerata first pr appendages
chelicerae
Chelicerata 2nd pair appendages
pedipalps
Chelicerata classes
Merostomata
Arachnida
Pycnogonida
Merostomata
1 genus (4spp.) extant, marine, horseshoe crab
Merostomata e.g.
Limulus sp.
horse shoe crab
Merostome morphology
2 tagmata: prosoma (A), opisthosoma (P);
telson, compound eye (unique)
Merostome prosoma
shovel-shaped to facilitate sediment burrowing
telson
not true metamere, hinged to body, d-v movements, aids in ‘righting’ flipped over body