Midterm Flashcards
plankton
drifting organisms that inhabit the pelagic zones of oceans, seas, or freshwater bodies of water
function (metabolic) difference in plankton
zooplankton and phytoplankton
zooplankton
heterotrophic, use oxygen, produce carbon dioxide
phytoplankton
autotrophic, use carbon dioxide, produce oxygen
alternate metabolic needs of plankton means
zooplankton and phytoplankton may inhabit different areas
life history differences in plankton
holoplankton and meroplankton
holoplankton
whole life cycle as plankton, eg. copepods, dinoflagellates
meroplankton
part of life cycle as plankton, eg. trochophores, tadpoles
meroplankton life cycle
biphasic (metamorphic) life cycle
biphasic (metamorphic) life cycle
larval stage (plankton) metamorphoses to a juvenile stage (benthic)
alternative life stages in biphasic (metamorphic) life cycles
many metamorphic life cycles have alternative life stages (even so much as direct) which provides evidence of the transition between life cycles evolutionarily
C. elegans have what life cycle
non-metamorphic (direct)
sand dollars and sea biscuits have what life cycle
biphasic (metamorphic)
biphasic life cycles are subject to unique selective pressures
at the planktonic and benthic stages
each life stage in the biphasic life cycle becomes
more divergent in response to unique selective pressures at each life stage
biphasic life cycles life stages
planktonic and benthic
possible selective pressures in the planktonic life stage
currents, swimming, predation, biotic and abiotic pressures requiring sensory structures (like rapid changes in temperature dependent on position in water column)
possible selective pressures in the benthic life stage
competition (more-so than plankton because environment is very selective), predation, biotic and abiotic pressures requiring sensory structures (less-so temperature but increased potential for turbulence)
possible advantage for being planktonic
dispersal potential to colonize new habitats, competition avoidance (massive space availability), large array of factors contribute to diversity
possible disadvantages for being planktonic
susceptibility to predation (little shelter), buoyancy (must hold position in the water column using air chambers), swimming considering Reynold’s number
possible planktonic predator avoidance strategies
transparency, bioluminescence, mechanical (spines), chemical (toxins), migrations (diurnal vertical migrations – photosynthetic need, evasion of predators), predator detection
transparency is common across how many major taxa, including
10 major taxa, including chaetognatha, ctenophora, and cubozoa
mapping functional characteristics on top of a phylogeny
allows you to make a hypothesis (on top of the phylogeny hypothesis)
there is an association (co-occurrence) between what 2 lifestyles
transparency and pelagic lifestyles
transparency is uncommon and common in what systems
uncommon in terrestrial systems and common in marine and freshwater systems
Snell’s window
predators looking up to the water’s surface have a broad view (and can further identify shadows) because the angle of light changes between mediums of different densities
transparency is advantageous over pigmentation at
shallow depths to limit shadows from down-dwelling light
pigmentation is advantageous over transparency at
deeper depths where pink pigmentation is best camouflaged in the penetrating red/pink wavelengths of light
although red/pink pigmentation is advantageous at deeper depths
predators tend to use bioluminescence at these depths so prey must employ counter-strategies
dynamic transparency
optimal camouflage regardless of depth, eg. cephalopods
bioluminescence is effectiveky
chemiluminescence in vivo
bioluminescence contributes to predator avoidance
bioluminescence may startle predators, may inhibit a predator’s ability to discern an individual when exhibited by a group, may act as a warning display (appear larger), may act as camouflage (when adjacent to other bioluminescent organisms)
bioluminescence has evolved
more than 40 times across animal taxa, and based on trait distribution probably evolved independently multiple times (homoplasy)
homoplasy
evolution of a trait multiple times independently
luciferase
catalyzes luciferin in a chemical reaction to produce light, often catalyzed by movement, requires modification of protein
fluorescence
physical process whereby an electron is excited and fall back to its ground state by emitting a photon
daphnia require stationary water
for sufficient algae to filter from the water, thus there are few marine species
daphnia are “transparent”
for the purposes of murky pond water
daphnia ocellus
compound eye
daphnia females
greatly outnumber males
daphnia phenotypic plasticity
helmet, core body, apical spine, more hemoglobin in low oxygen environments (pink), less hemoglobin in high oxygen environments
parthenogenetic life cycle, daphnia
females produce diploid females under optimal conditions, defined as immortal because they reproduce asexually
sexual life cycle, daphnia
females produce diploid males and haploid eggs under stressful conditions
male daphnia breed with female daphnia, which leads to the formation of
ephippia, embryos that are able to arrest in development as in diapause
ephippia resume development
when the environment allows for it
daphnia undergo a developmental what in sexual production
staging scheme
growth trajectory
size vs time
developmental trajectory
developmental stage vs time
daphnia helmet, core body, and apical spine length change in response to
predators, predator species may secrete a signal
cyclomorphosis
occurrence of cyclic or seasonal changes in the phenotype of an organism through successive generations
invertebrates that exhibit cyclomorphosis
small aquatic invertebrates that reproduce by parthenogenesis and give rise to several generations annually
daphnia produce eggs
after every molt
daphnia molts release
calcium back into the environment
life history
stages of growth, reproduction, and dispersal than an individual goes through during its life from birth to death
life histories are inconsistent even
within groups of a species
life history theory
the allocation of energy through life history differs
life history theory has successfully explained
why organisms are small/large, mature early/late, produce many/few offspring, have a short/long lifespan
energy supports growth
may be linear, stagnated, or some combination
energy is provided by the moth
based on the extent to which the mother supplies energy varies (size of egg)
energy supports reproduction
reproductive events over entire lifetime, singular events, multiple events
energy and lifespan
massively different ages between organisms even within a species
small vs large organisms based on
size at brith, size at maturity, growth pattern (between life stages), reproductive investment, habitat (nutrient./shelter availability)
longevity of organisms based on
mortality/survival rates, sensescence
longevity
potential lifetime excluding catastrophic events
mortality/survival rates are based on
endogenous and exogenous factors
senescence
process of deterioration with age
reproductive output of organisms based on
reproductive investment, size (growth rate), longevity (number of reproductive events), age at maturity
impact of sexual vs asexual reproduction
red sea urchin (sexual) produces millions of spawn but has hardly changed since Cambrian times, daphnia (asexual) produce few clones but has changed greatly since the Cambrian times (minor changes in mother must produce changes in offspring)
life histories evolve as a result
of interactions between extrinsic and intrinsic factors
extrinsic factors
affect age specific rates of mortality and reproduction (ecology)
intrinsic factors
trade-offs in physiology, development, genetics, and phylogeny (inherited trait can be of benefit or detriment)
planktonic life histories correlated with dispersal potential
planktotrophic - little provision from mother but more offspring, lecithotrophic - more provision from mother (yolky egg) and still many offspring, direct - high provision from mother for juvenile to adult stages
planktotrophic
little provision from mother
lecithotrophic
more provision from mother, yolky egg
trade-offs consider
how life histories are related
trade-offs are necessary for 3 reasons
the amount of energy available is finite, biological processes take time (the build up metabolic energy required), every organism’s life history is an evolutionary compromise (resource allocation trade-off)
direct constraint exists between 2 allocations for energy
somatic function and reproductive function, must live to reproduce, but energy into growth inhibits reproduction
trade-off prediction
fitness is optimal at either end of the investment spectrum
fitness is optimal at either end of the investment spectrum – number of offspring vs investment per offspring
divergency between few offspring/high investment per offspring and many offspring/low investment per offspring – few species exhibit some offspring/medium investment per offspring
fitness is optimal at either end of the investment spectrum – reproductive capabilities vs growth rate
time to grow to a certain stage has an inverse relationship to fertilization events, but does not produce the divergence seen in number of offspring vs investment per offspring
trade-offs only exist when
there are limited, equal resources allocated between traits
not everything is based on the effects of trade offs
constraints exist
ecotoxicology
synthetic science, study of the effects of toxic chemicals on biological organisms, especially at the population, community, ecosystem, and biosphere levels – use models, organisms best suited for studies – consider interactions in the broader – integrates toxicology ecology, and chemistry
cause-effect paradigm
the dose determines that a thing is not a poison, Paracelsus
pharmaceuticals need to overcome
cell capability to ‘pump out’ a foreign material
dose response curve
concentration vs effect, determine impact of concentration in environment
NOEC
no observed effect concentration
LC50
lethal concentration to kill 50% of the population
DDT is
an estrogenic mimic, binds to estrogen binds involved in shell thickening
DDT in vivo
shell thinning
DDT in situ
bioaccumulation leading to bird population decline
SSRIs
selective serotonin re-uptake inhibitors, thought to block the reabsorption of serotonin from the synaptic cleft (conserved pathway common in invertebrates and vertebrates
SSRIs are introduced to the environment in 2 ways
human and animal consumption followed by residual excretion, agricultural and industrial run off – incomplete filtration of waste water
polarization vision
natural polarizing filters in the eyes of organisms can filter out light wavelengths vibrating in select directions, increases contrast, which may explain some behaviours
polarization in shallow reefs
horizontal polarization
diel vertical migration selective forces
feeding, photosynthesis, protections from predation
diel vertical migration phytoplankton
down at night (use stored energy and switch to heterotrophic metabolism) and up during the day (photosynthesis)
diel vertical migration zooplankton
migrate up at night (exhibit bioluminescence) and down during the day (despite feeding on phytoplankton)
sensitive detection of predators and escape response
cost/benefit of increased susceptibility due to greater detection (movement) and increased vulnerability due to delayed escape
escape threshold
partial explanation of jerking movements of copepods, cost/benefit of increased susceptibility due to greater detection (movement) and increased vulnerability due to delayed escape
5 ways to maintain position in the water column
via floats (air chambers), lipid accumulation (change in density), shell loss (less restrictive), selective ion regulation (create change in osmotic pressure for change in density), decreasing the sinking rate (extension of skeletal appendages
one dinoflagellate species makes ‘fingers’ containing
chloroplasts each morning that are resorbed at night - consider the cost of making fingers and rebuilding chloroplasts and benefit of having a reduced sinking rate and optimal position for photosynthesis
Reynold’s number, Re
LS/Vk L length of moving object S velocity of moving object L•S inertial force Vk kinematic viscosity, viscosity constant as an assessment of the environment - changes with temperature
Re > 4000
inertial force dominant
Re < 1000
viscosity force dominant
Re and temperature, gas
direct
Re and temperature, liquid
inverse
planktonic organisms exist in Re environment
viscosity force dominant, inertia is negligible so streamlining not important, flow reversible, symmetrical flapping strokes ineffective – need power and recovery strokes or helical waves of bending
eutrophication
excessive richness of nutrients in a body of water, frequently due to runoff from land causing a dense growth of plant life and death of animal life from lack of oxygen
boundary layers
area above a surface
“skin breather” requires
tight integration of circulatory system
“skin breather” impacted by 4 factors
size, shape, metabolism (heterotrophic organisms require a lot of oxygen and must dispose of a lot of carbon dioxide), activity (consider diurnal activity - may involve changes in metabolism, periods of metabolic recovery like in phototrophic plankton)
Fick’s Law
semipermeable membranes achieve equilibrium with protein channels and carriers, particles move by diffusion
Fick’s Law variables
M rate of diffusion D diffusion coefficient A area C concentration gradient L barrier thickness
2 boundary layer characteristics
velocity decreases exponentially and is slowest nearest the barrier, increasing the velocity of flow decreases the size of the boundary layer but decreases the concentration of particles
boundary layer and the benthic phase
settling involves intense turbulence, but as velocity decreases so too does turbulence at which point they are able to settle
3 ways to disrupt the boundary layers
fluid flow via cilia, fluid flow via appendages, whole body movement (in the absence of specialized structures)
there is incredible unity and diversity in respiratory structures
unity of function, diversity of structures
free path
average distance traveled by a moving particle between successive collisions with other particles
gas exchange in air vs water
O2 content higher in air density lower in air diffusion coefficient high in air free path higher in air velocity equal collisions per second higher in air
tracheal system limits
body size - ~300 mya hexapods were significantly larger suggesting the greater availability of atmospheric oxygen allowed for greater metabolism and therefore greater body size
tracheal system limits and beetles
a greater fraction of the body is dedicated to respiratory system with increased body size, space available for the trachea within the leg may ultimately limit the maximum size of extant beetles – functional cannot have massively long legs – consider how metabolism scales with body size
fundamental limits of diffusion
the 1 mm rule, beyond which diffusion is inefficient
escaping the fundamental limits of diffusion
circulation which provides convective delivery and disrupts boundary layers, creating a new 1 mm rule using pump, pipes, and pigments
in hexapods and myriapods, the primary function of circulation
is the transport of nutrients
circulation
transport of gases, nutrients, wastes, hormones, immune components - locomotion
circulatory pumps
muscular heart structure (worm) vs more continuous flow (sea star madreporite) vs pulmonary and systematic system (cephalopods)
cephalopods display a convergence of circulatory structures with humans
closed system, capillaries, endothelium, systemic heart, branchial hearts
circulation and locomotion
echinoderms, coordinated movement of tube feet using water vascular system and muscular system by nervous system for highly coordinated movement
circulation and gas exchange
echinoderms, tube feet critical to gas exchange
4 respiratory pigments
hemoglobin, hemocyanin, chlorocruorin, hemerythrin
hemoglobin
red, Fe, free / corpuscular, all major groups
hemocyanin
blue/green, Cu, free, molluscs and arthropods (larval storage proteins are derivatives of hemocyanin and carry immune function - horsehoe crab blood added to vaccines to suppress immune response)
chlorocruorin
free, Fe, free, sessile marine polychaetes
hemerythrin
colourless/pink, Fe, corpuscular, sipuncular (peanut worms) and brachiopods
oxygen binding curves
partial pressure vs % saturation
high affinity for oxygen if
max content at low partial pressure
low affinity for oxygen if
max content at high partial pressure
oxygen requirements are related to oxygen affinity
low metabolism, hypoxic environment, high affinity
effects of rising CO2 levels
oceans absorb large amount fo atmospheric CO2, organic matter under glaciers (permafrost) is melting contributing further to CO2 levels, change in water chemistry
when CO2 dissolves in water
bicarbonate ions decrease and hydrogen ions increase, lowering water pH
pH sea water
pH freshwater
pH sea water = 8 (more ions available to buffer)
pH freshwater = 5-6
pH of oceans has changed from 1751 to present
pH decreased 0.1 units, 30% rise in H+ concentration, projections of a further doubling or tripling by 2100
animal that require saturated levels fo carbonate ions
sea urchin larvae and mollusc larvae
sea urchin larvae require saturated levels of carbonate ions
skeletal rods (for swimming and feeding) form as a result of complex interactions, active calcium transport into site of calcification (syncytium), metabolic problem in chronically elevated CO2 water: calcium harder to take up and incorporate so more energy is invested into skeletal rod formation and less energy is available for swimming and feeding
mollusc larvae require saturated levels of carbonate ions
shells are essential for protections a shelter, both CO2 and temperature are stressors (consider the summation of stressors)
community structure changes in response to elevated CO2
phytoplankton and zooplankton
phytoplankton and community structure changes in response to elevated CO2
some benefit from increased temperatures, hypoxic zones create dead zones where phytoplankton blooms, eutrophication supports blooms of some species (some of which release toxins), increased phytoplankton biomass leads to increased waste products and increased bacterial decomposer mass, bacterial growth further depletes O2
zooplankton and community structure changes in response to elevated CO2
copepods, indirectly benefit from elevated CO2 via food web effects, rise in red tides
organisms gain and lose significance in the community structures as a result of
abiotic filters and biotic filters
example of abiotic filter
pH
example of biotic filter
predator
CO2 availability has the same impact as
predator availability, but these are different types of filters
median lethal dose
LD50, dose required to kill 50% of test population
median lethal time
time required to kill 50% of test population
sublethal threshold
“stress to low oxygen”
hypoxic
low oxygen conditions, conventional cut-off 2 mg O2/L
hypoxic conditions produce
a reduction in variance, but crustacean O2 lethal threshold is significantly higher and more variable than other taxa
excretion
need to excrete catabolic waste, primarily through nitrogenous wastes from protein breakdown
4 types of nitrogenous wastes
ammonia (NH3, most common, both gaseous and liquid form), urea (polychaetes), uric acid (mammals), guanine
excretion in sponges, cnidarians, ctenophores, echinoderms
no specialized structures
excretion in platyhelminths, nematodes, annelids
nephridia
excretion in crustaceans
antenna gland
excretion in insects
Malpighian tubules
excretion in molluscs and vertebrates
kidneys, though term used inconsistently across groups
2 main types of excretory systems
nephridia and coelomoducts
nephridia
ectodermally derived, grow in
coelomoducts
mesodermally derived, grow out
2 types of nephridia
protonephridia and metanephridia
protonephridia
tubules, not very specialized, ciliated, flame cells (dead end tubules)
metanephridia
tubules connect to coelom so can establish a connection between internal and external environment, more specialized, ciliated, blood pressure drives fluid into their structures for more efficient reabsorption
coelomoducts are similar to
genital ducts, hypothesis: excretory function is secondarily derived so less efficient and confined to certain segments (whereas protonephridia exist on all segments)
excretion in leeches
nephridia, high protein/volume/inconsistent blood meal requires specialized structures for rapid increases in catabolic protein waste, ammonia waste product requires less energetic investment but demands water, muscular contraction help push blood meal through the body, observe coelomic reduction - coelomic cavity is rich in blood vessels to increase efficiency of absorption
excretion in molluscs
‘kidney’, large complex metanephridium (though differently derived than vertebrate kidney), associated with pericardial cavity, heart drives maximum pressure through this form of ultrafiltration, renal sac or ‘bladder’, release of primary urine into mantle and then external environment
2 types of excretory processes
ultrafiltration and active transport
ultrafiltration
filter membrane, semi-permeable membrane
active transport
requires energy, transport solute against the electrochemical gradients, secretion of particles into lumen of excretory organ and the reabsorption of water and other compounds (but many compounds chemically similar to nitrogenous waste products)
osmolarity
number of solutes per volume, often expressed on moles
1 mol glucose
1 mol NaCl
[NaCl] human body
[NaCl] salt water
1 mol solute
2 mol solute (dissociation of ionic bond)
[NaCl] human body 300 mM
[NaCl] salt water 1000 mM
Humans face net loss of water when immersed.
2 ways to combat osmotic problems
osmoregulator and osmoconformer
osmoregulator
maintain internal environment
osmoconformer
change internal environment with external environment
physiological regulation is parameter specific
regulating or conforming is parameter-specific
physiological regulation of salinity in marine and brackish water invertebrates
conformers, but when [salt] decreases there is some regulation of [salt] for physiological function, not conformers in lower and higher [salt] environments
physiological regulation of salinity in freshwater invertebrates
regulators, will always combat water entering the cell so must use energy to pump water out because ion solution in will always be higher than out, note regulators in lower [salt] environments only
regulators and carapace
permeability fo the carapace varies dramatically and impacts salt loss
spiracles
connections between external environment and tracheal system; removes CO2 in heterotrophic metabolism and allows for gas exchange with minimal water loss – can actively open and close, surrounding hair-like structures change air flow
closed spiracles: water loss and metabolism
decrease water loss in a non-linear relationship to temperature), does not effect metabolism in the short term (enough gases in system to maintain heterotrophic metabolism)
xerophilic
scorpion - active in dry conditions, tolerant to desiccation
hygrophilic
snail - active in wet conditions,
tolerant to desiccation
cryptozoic
potato bug - active in dry conditions, intolerant to desiccation
aquatic
cnidarians - active in wet conditions, intolerant to desiccation
supercooling
exposure to temperatures conducive to freezing yet does not freeze, inhibits cell rupturing via anti-freeze proteins actively pumped into cells to inhibit water crystallization
2 disadvantages of supercooling
metabolism is higher and water loss is greater in the supercooled state than in the frozen state
cryptobiosis
extremely low metabolism (found in bacteria), allows for freezing
anhydrobiosis
self-desiccate (reduce body water levels) so as to survive freezing conditions
cryptobiosis and anhydrobiosis
replace water with sugar which act as anti-freeze compounds to help preserve structures - rotifers, nematodes, tardigrades - evolved before animals, independent evolution
waterproofing mechanism in dry environments
hexapods, myriapods, arachnids - discrete wax layer, suitable in normal temperature range but limited at some threshold (30˚C) at which point it becomes more porous so more permeable to water
namib beetle
xerophilic adaptation - cuticle protects from water loss, fog gathering: crawls up dune in Namib desert when fog approaches and raises abdomen, water condenses on hydrophilic bumps on cuticles and water runs down into mouth
evolutionary traits evolve as a result of
Darwinian adaptation: heritable variability, overproduction, differential survival and reproduction, shifts in gene frequency
most widespread form of consumers
deposit and suspension feeders
5 types of consumers
hunters, parasites, deposit feeders, sedimentation interceptors, suspension feeders, grazers/browsers
in precambrian times, fossil evidence that the majority of organisms live in and are
in sediment (benthic zone) and are deposit feeders, except sponges (suspension feeders)
cambrian explosion
~600 mya
deposit feeders
primarily live in the sediment (benthic zone), feed on decomposed organisms including bacteria, fungi, and other microorganisms (nematodes, amoeba, and ciliates also live in the same zone so are ingested) so in some ways, an entire microbiome, an entire food web
advantages of deposit feeding
dead material falls down water column so decomposition vital to support energetic needs
disadvantages of deposit feeding
below the photic zone, cannot graze on plants
2 types of deposit feeders
direct and indirect
direct deposit feeder
non-selective, wholesale consumption
indirect deposit feeder
selective, mechanisms to sort through sediment prior to ingestion
2 animals that exhibit both direct and indirect deposit feeder behaviours
sea cucumbers (primarily direct deposit feeders but are sometime indirect, use buccal tentacles for gas exchange and grazing), earthworms (direct deposit feeders when they make their burrows, indirect deposit feeders when they feed on leaves and detritus on the soil surface)
examples of indirect deposit feeders
amphitrite (spaghetti worms), polychaetes, spoon worms, peanut worms, peppery furrow shells (use of inhalant and exhalant siphons that protrude out of sediment), scaphopod molluscs
scaphopod molluscs
indirect deposit feeders, introvert structures, tentacles (captacula) with palps stick out of shell, mucous released from papillae on tentacles, ciliary tracts move particles towards mouth (frilly lips)
in contrast to molluscs, bivalves are more derived and use
filter feeding (suspension feeding)
sedimentation interceptors
live in or on the sediment (benthic zone) with deposit feeders (for safety) and filter water (more active than suspension feeders) - no specialized structure for deposit feeding
examples of sedimentation interceptors
crinoids (crawling/stalked and swimming/non-stalked crinoids) are opportunistic feeders that hunt, filter, deposit feed (no specialized structures) and basket stars (primary, secondary, and tertiary tube feet each with different function for feeding, respiration, and movement to direct particles to mouth, papillae release mucous which is also brought to the mouth for ingestion)
suspension feeders
live out of the sediment and within the plankton, remove particles from the water column, derived function, use flow and capture structures, mucous probably evolved multiple time independently (convergent evolution)
suspension feeding is a laborious task
little concentration, particles very diverse in size/nutrient values, etc.
2 main strategies for suspension feeding
muscociliary, setal system
muscociliary
suspension feeding, combine mucous and ciliary function - active process
setal system
suspension feeding, “coffee filter” - less active process
examples of suspension feeders
bivalves (except scaphopods), tunicates, barnacles (bryozoans move locophore (tentacle crown) and use cilia and mucous), brachiopods, sponges (choanocytes), chaetopterus (mucous net sent out into plankton)
sponges and suspension feeding
choanocytes both create a feeding current (flow) and capture particles
chaetopterus and suspension feeding
mucous net sent out into plankton, more specialized
deposit feeders are limited by
food availability
suspension feeders are limited by
space because food availability is not the limiting factor
mucociliary capture in suspension feeders
cilia used in suspension feeding, possibly in addition to swimming and orientation in the water column
3 types of mucociliary capture in suspension feeders
downstream food collection, upstream food collection, ciliary sieving (with mucous papillae)
downstream food collection
suspension feeding, polychaetes, molluscs, gastropods, power-stroke of cilia transports food directly to mouth using multiple bands of cilia, groove directs food to mouth
upstream food collection
suspension feeding, thought to belong to deuterostomes because exhibited by brachiopods and echinoderms but brachiopods are no longer considered deuterostomes, mouth upstream of 1 continuous band of cilia creating current
ciliary sieving (with mucous papillae)
suspension feeding, non vertebrate chordates only, cilia structure completely different from swimming structures, branchial arch in cephalopods are homologized developmentally to combine cephalochordates with deuterostomes
phase of a biphasic life cycle that should be used to determine phylogenetic relationships
larval stage, symmetry and structures common in larvae (but not adults) better indicate taxa relationships – previous belief that larvae were ancestral traits but sometimes metamorphosis evolved secondarily
6 mucociliary capture mechanisms
direct interception (may have mechanoreceptors which lead to dynamic response), inertial impaction (disrupt inertial flow), gravitational deposition (falling particles), diffusional deposition (with laminar flow, concentration gradient based on difference in speed), electrostatic attraction, dynamic response of cilia and tentacles
plasticity, rather than rigidity, may or may not increase fitness in
a variable environment
echinopluteus larvae plasticity
grow longer arms in low food conditions and shorter arms in high food conditions - has one continuous band of cilia
costs of echinopluteus larvae plasticity
energetic costs (increased size, but decreased Ca from environment with ocean acidification, and decreased energy available for fecundity), increased visibility to predators
benefits of echinopluteus larvae plasticity
more food can be collected, protective spine from predators, better swimming capabilities
there are limitation to the cost vs benefit approach to develop hypotheses because
we are never completely aware or able to assess all cost and benefit traits, evolutionary and proximate constraints exist
3 primary lifestyles of hunters
pursuit hunters, searchers, and ambush predators
pursuit hunters
cephalopods, dragonflies, in order to be effective: must be faster than prey, have nervous system adaptations specific t being mobile, specifically sensory adaptations to detect prey
advantages of pursuit hunters
highly mobile, fast
disadvantages of pursuit hunters
fast movement is energetically costly and may constrain behaviour, fast movement equates to higher visibility to predators
searchers
hunters, sea stars, nemerteans, molluscs, in order to be effective: must actively forage (active on a different time scale), have adaptations related to the recognition (eg. sensory receptors in sea star tube feet to minimize time spent hunting), handling, and digestion of prey, possess toxins to immobilize prey
advantages of searchers
actively moving to avoid predation
disadvantages of searchers
the energy of a meal has to be greater than the energy invested in searching, handling, and digesting the meal
ambush predators
hunters, praying mantis, cone snail, in order to be effective: must camouflage, have adaptations related to catching behaviours (fast transition between sedentary and active states), possess toxins to immobilize prey
advantages of ambush predators
less visible to predators with minimal movement
disadvantages of ambush predators
short window of opportunity (opportunistic feeders) to kill prey
cone snail feeding
ambush predator, everts proboscis which possesses harpoon-like structures, which injects toxin (conotoxin, dangerous to humans if the snail preys on fish) to immobilize prey, produce venom in venom bulb (gland) which travels via the venom duct to the radular sac which possesses the harpoon-like structures
cone snail venom
trialed as cancer therapy drugs; exploit the effects on the human immune system, potential use as pain-killers
uropygi (vinegaroons)
ambush predators, produce vinegar to immobilize prey, which also aids in digestion
7 morphological adaptations for handling prey
grasping limbs, eversion of pharynx, inhalant siphon, modified gills, suckers on tentacle arms (cephalopods), suckers with modified hook structures (giant squid), basket structure of cephalic spines with hooks (chaetognaths)
3 examples of grasping limbs as morphological adaptations for handling prey
pedipalps (arachnids and chelicerates), subchelate legs (praying mantis and some shrimp species), claws (modified chelate legs with fine motor control in crustaceans)
