Oceanography Exam #3

phytoplankton are responsible for about ___% of global productivity, but only about ___% of total plant biomass.

40, 1

when did the late Ordovician period occur?

450 million years ago

in terms of where they live, marine animals can be:

epifaunal or infaunal

zooplankton

animal plankton that graze on phytoplankton and, in some cases, other zooplankton -grow to become small crustaceans and the larvae of larger organisms

types of caudal (tail) fins

rounded, truncated, forked, lunated, heterocercal

prokaryote

unicellular organism lacking a nucleus -have evolved to take advantage of almost every possible energy pathway, which allows them to be so diverse -these energy pathways aren't as efficient or available as those used by eukaryotes, but there are many more of them than those used by eukaryotes -not well-suited to becoming large, complex organisms because the cells can't specialize in specific tasks >> organisms don't put much energy into differentiation

is there more chlorophyll in the open ocean or in upwelling zones?

upwelling zones

where does the highest rate of primary production typically sit?

typically, it sits somewhere beneath the water surface (30-50 m. below) rather than right at the surface

what happened during the early Permian period?

-North America collided with South American and Africa, forming the Appalachian mountains -now an ice sheet in the Southern Hemisphere, so sea level had dropped → new supercontinent of Pangea created from this collision

phytoplankton buoyancy

-although they cannot swim per se, many larger phytoplankton can control or limit their sinking rate by: (1) storing fat lipids to reduce their density (oil floats in water) — this requires an excess of food production that is only likely to occur in upwelling zones; (2) some species have flagellae, which serve as small tails for slow locomotion, but only enough to balance sinking so they do not consume too much energy

general distribution of ocean sediments

-continental margins have most sediment, mostly derived from rivers and, at high latitudes, also glaciers -open ocean, away from continental influence, are mainly wind-blown lithogenous sediments (clays) and siliceous and carbonate biogenic sediments -the distribution of open ocean sediments reflects oceanographic processes, such as upwelling (for siliceous seds), deep-ocean circulation (for carbonate seds)

heterocercal caudal fins

-mixes two types of tails → one that's good for slow swimming and one that's good for high speed -ex: sharks

adaptations

-organisms can be adapted to ocean life through their morphology (shape), physiology (function), and/or behavior -environmental factors requiring adaptation include salinity, temperature, and light, as well as predation and competition for nutrients, food, and space

how does the rate of photosynthesis and respiration change with depth?

-photosynthetic rate is lower at the surface, peaks between 30 and 50 m. depth, and then continues to decline with depth -respiration rate = amt. of energy that the plant needs to survive -plants respire the food that they produce in order to extract the energy back when they need it

oceanography of TN

-this region has exposed limestone rocks from the Ordovician period (~450 mya) -the rocks (formerly sediments) were formed by plants and animals living in a shallow tropical ocean setting (not unlike modern Bahamas), when North American was located in the tropics just south of the equator -major extinction occurs at the end of the Ordovician period when a strong glaciation occurred on the southern continents, lowering sea level and exposing the shallow seas to become land (i.e. those critters lost their habitat) -the ocean next to TN/North American was closing up, ultimately leading to a continental collision with Europe/Africa the formed the Appalachians ~250 mya

when did the early Permian period occur?

280 million years ago

____% of ocean productivity (about 1/2 of world productivity) occurs in less than ____% of the ocean, specifically along coasts and at upwelling zones.

99, 20

photosynthetic reaction

CO2 + H20 + light/nutrients >> C6H12O6 (sugar) + O2

respiration reaction

C6H12O6 (sugar) + O2 >> CO2 + H2O

swim bladder

a gas-containing, flexible, cigar-shaped organ that aids many fishes in attaining neutral buoyancy -all fish have one → fish can change their buoyancy by increasing or decreasing the size of it bigger swim bladder means the fish is less dense and can float upward -fish control its size through the bloodstream → they increase their blood flow to constrict the swim bladder and reduce buoyancy -pressure changes as fish move through the water column → fish have to adjust their buoyancy as they move through it

euphotic zone

a layer in the ocean that extends from the surface to a depth where enough light exists to support photosynthesis, rarely deeper than 100 m. -this zone encompasses anything above the compensation depth

active transport

a mechanism that organisms may use to import rare, valuable nutrients that cannot be easily obtained through the regular diffusion process

echolocation

a sensory system in which usually high-pitched sounds are emitted and their echoes interpreted to determine the direction and distance of objects -echolocation works like sonar and gives information about the size, shape, distance, speed, and direction of an object -developed as a necessary compensation for reduced visibility in the oceans -high-frequency sound generated in nasal cavity and focused by lip-filled (fat) "melon" -returning sound is received along the lower jaw and focused toward the inner ear by a similar lipid-filled cavity -sperm whales have formal air sac sitting at bull-shaped part of the school to make a larger sound than dolphins can make → puts out high-powered sound that extends further out into the water column and can detect prey even further away than dolphins can

phytoplankton

algal plankton that are one of the most important communities of primary producers in the ocean → make up the base of the food web -includes diatoms and dinoflagellates

is there more chlorophyll in the open ocean or along the coasts?

along the coasts

what are the two different hunting styles of nekton?

ambush or chase

stable isotopes

an element having a different number of neutrons in its nucleus which affects the mass of the element (more neutrons = greater mass); hold essential data for recording Earth history -foraminifera are amoebas with shells made of calcium carbonate that record the chemistry of the ocean water through stable isotopes -oxygen atom: always has 8 protons, but neutrons can vary between 8, 9, and 10; oceans typically have 99:1 ratio of 16O: 18O, and this oxygen is predominantly tied up in H2O -oxygen isotope record: shows the transition of earth from warm, greenhouse tropical climate of the dinosaur age to the gradual glaciation of earth → all of these changes in earth's history are recorded in zooplankton shells found in the deep ocean -delta 18O values in ocean plankton reflect two things: 1. temperature of the ocean water — organisms will take up different amounts of heavy or light water depending on the temperature; 2. the ratio of 16O:18O in the oceans — this varies with the amt. of water stored in ice sheets on land

deposit feeders

animals that ingest the sediment and the nutrients in it that have sunk down from the surface -this food source isn't as fresh or nutritious as plankton that filter-feeders consume, but it's much abundant

filter-feeders

animals that pump water through their bodies (typically across their gills) → oxygen diffuses into their bloodstream through gill plates → gill plates have evolved to filter out the microscopic plankton in the water and channel them down to the gut -i.e., barnacles, mussels, anemones -very efficient way to live in the ocean because they're doing the same activity to breathe and get food while pulling in live plankton as their food source (very nutritious and high quality)

three taxonomic domains of life

bacteria, archaea, eukarya

what do upwelling zones and coasts have in common with respect to primary productivity?

both areas are nutrient-rich -in upwelling zones, water is drawn up from the deep ocean and into the light zone -off the coast, the main supply of nutrients comes from the land (such as from river runoff and groundwater)

how are complex, interacting networks of organisms organized?

by taxonomy, tropic roles, and habitats

what's the difference between brachiopods and clams in terms of their roles as prey in the ecosystem?

clams living in the seabed were much better protected and hidden from predators than brachiopods, but in the Ordovician, brachiopods had the advantage still because the only predators out there were cephalopods which could only feed on soft-body organisms → brachiopods were entirely safe being out in the open in the water column

where is all food produced in the ocean?

close to the surface

do simple organisms or complex organisms have more energy competition?

complex organisms (eukaryot) -these organisms have more energy competition than simple organisms and are also more efficient than simple organisms -they evolve due to competition for resources which in turn makes them more efficient in utilizing these resources -results in them having greater morphological diversity than simple organisms

types of plankton

coccolithophores, diatoms, dinoflagellates

do simple organisms or complex organisms have greater morphological diversity?

complex organisms

trophic roles

concerned with the transfer of matter and energy through nourishment -can change through an organism's life -plant producers constitute the lowest trophic level, followed by herbivores and a series of carnivores at the higher levels -autotrophs (aka producers) make their own food -heterotrophs (aka consumers) eat other things

infaunal

describes animals that live in or beneath the seabed (in the sediment) → they have safety, but if something comes to eat them, they don't have mobility cause they're stuck in the seabed

epifaunal

describes animals that live on the ocean bottom, either attached or moving freely over it → they have mobility, but not much safety

in terms of what they eat, marine animals can be:

filter-feeders or deposit feeders

how do fish and marine mammals stay aware of their surroundings?

fish use their lateral lines, mammals use echolocation

nekton

free-swimming animals that can move throughout the water column -mostly vertebrates (squids are the main exception) -mostly fishes (marine mammals are the main exception) -many species live in the photic zone (i.e. surface ocean) → those who live outside of this region (away from where most of the food is) do so because it's safer down there -hunting styles: chase vs. ambush; deep ocean fish are mostly ambush predators because they can't see, so it's more energy efficient to wait for things; surface ocean fish are mostly chase predators because it pays to be fast (predator and prey can see one another)

what was TN like in the early Ordovician period?

had shallow sea, deep offshore ocean water, lagoons, and reefs

what is the limiting element in large areas of the ocean that often times prevents photosynthesis from occurring when it would otherwise be able to?

iron

what three things do phytoplankton require in order to photosynthesize?

light, nutrients (nitrogen, phosphorous, carbon, silicon for building proteins, etc.), and water

major sediment types

lithogenous, biogenous, hydrogenous, cosmogenous

what factors make it so calcium carbonate shells dissolve below the compensation depth?

lower temperature, high pressure, high CO2, low pH (more acidic)

osmoregulators

marine organisms that maintain a constant internal osmotic environment no matter the conditions of their surrounding external environment -they have to maintain a constant body salinity no matter the salinity in the water → becomes an issue if they live off the coast because water can change from seawater into fresh water pretty quickly -they have to regulate their own osmotic process -fish and other complex organisms are osmoregulators

diffusion

molecule movement from areas of high concentration to low concentration → very slow process -organisms don't have to do anything for this mechanism to take place -this is one mechanism for exchanging salts and uptaking nutrients -because nutrients are usually plentiful in seawater, they pass through the cell wall into the interior, where nutrients are less concentrated -in addition to passive diffusion, organisms also import nutrients to cells by active transport (specially formed binding sites can be used to pull in rare, valuable nutrients → may be advantageous to develop an active mechanism for obtaining these nutrients)

five kingdoms of organisms in eukaryotes

monera, plantae, animalia, fungi, protoctista

what are the three processes that influence adaptation?

morphology (body form), physiology (body function), and behavior (body action)

does the open ocean have efficient energy transfer from level to level in its food chain?

no, only about 10% of the energy in a level is transferred to the next level -there are many levels and the food web is more complex than in upwelling zones -nutrients are more efficiently recycled in these areas→ very little export of energy from photic zone to the deep ocean because there are more organisms involved that need to use the energy up

are there phytoplankton along the Pacific equator during El Nino and La Nina?

not during El Nino, but there are during La Nina

archaea

one of the three major domains of life -consists of simple microscopic bacterialike creatures (including methane producers and sulfur oxidizers that inhabit deep-sea vents and seeps) and other microscopic life-forms that prefer environments of extreme conditions of temperature and/or pressure (near boiling water, super salty ponds, sulfur-spewing volcanic vents, super acidic water, deep in Antarctic ice, deep in sediments, etc.)

bacteria

one of the three major domains of life -includes unicellular, prokaryotic microorganisms that vary in terms of morphology, oxygen, and nutritional requirements, and motility

meroplankton

organisms that spend only part of their larval stages as plankton before growing into nekton -exceptions include any animals that give birth to live young (i.e. some sharks, all mammals, some fish like seahorses)

what's the most efficient mode of metabolic transport for complex organisms?

osmosis -diffusion is slow and may limit metabolic processes, & active transport is costly in terms of energy

surface drag

results from the friction of water moving over the surface of an organism → rough skin creates lots of turbulence and as a result, the organism can't move very fast -this drag is reduced by smooth skin, small scales, and a slime coating

turbulent drag

results from the turbulence created when an organism moves -when an organism moves through the water, it creates turbulence and slows things down -this drag is reduced by preserving laminar flow (teardrop shape of fish) -water is gently parted around the shape and then replaced back

form drag

results from the water's interaction with the frontal area of an organism -when an organism moves through the water column, the front of it is the first thing that makes contact with the incoming water and the first thing forcing water to move around it -this drag is reduced by having a small frontal area relative to length (skinny)

biogenous sediment

sediment containing material produced by plants or animals, such as coral reefs, shell fragments, and housings of diatoms, radiolarians, foraminifers, and coccolithophores; components can be either microscopic or macroscopic -there are two main types of plankton: those that make their shells out of calcium carbonate and those that make them out of silica; typically, silica plankton live in cold water → not necessarily needed, but cold water indicates that upwelling is occurring and therefore, that there are lots of nutrients; calcium carbonate plankton live in warm surface water → calcium and carbonate are abundant in seawater, so it doesn't matter that there's no upwelling in these areas → they're still able to make their shells -sources: hard parts of plants and animals → in the open oceans, they mostly come from tiny plankton -sources of biogenic sediments: plankton in open ocean; corals, shellfish in coastal regions

fish lateral line

side canal that runs underneath the skin along sides of fish; contains a network of sensors that detects changes in water pressure and allows the fish to monitor vibrations in the water around them -pores connect side canal with the outside environment -changes in water movement (i.e. pressure) around the fish change water movement inside the canal -sensory cells at the base of the canals detect these changes -allows for the "feeling" of surrounding water → can detect predators, prey, currents etc. -fish use their eyes to look for prey and the lateral line to escape from predators

types of drag

surface, form, turbulent

taxonomy

the classification of organisms in an ordered system that indicates natural relationships -involves physical characteristics as well as genetic information >> this information is used to recognize organism similarities and then group them into increasingly less specific categories

osmotic pressure

the pressure that must be applied to the more concentrated solution to prevent water molecules from passing into it

osmosis

the process by which water molecules move through a semipermeable membrane from higher water molecule concentration (lower salinity) to lower water molecule concentration (higher salinity) -osmotic pressure = the pressure that must be applied to the more concentrated solution to prevent water molecules from passing into it -rather than the dissolved stuff moving through the water, the water is moving to balance out the concentration of salts and sugars

trophic efficiency: loss of energy

the transfer of energy between trophic levels is very inefficient, especially at the lowest level -the efficiencies of different algal species vary, but the average is only about 2%, which means that only 2% of the light energy available in the sunlit surface waters is ultimately synthesized into food by algae and made available to herbivores -when plants are photosynthesizing the energy available to them, only 2% of that energy is converted to energy (2% efficiency) -only about 10% of the energy is transferred between levels so barely any is left at the top of the food chain -when humans harvest the top of the food chain, we also impact the rest of the food chain because of all the energy transfer that must occur to sustain the organisms that we tend to harvest

plankton

tiny organisms that drift in the water -they can't swim against any current, so they're always at the beckon of how the ocean circulates and how the waves mix -types: phytoplankton (plants) and zooplankton (animals)

why do some fish travel in schools?

to reduce drag, for better production, and for reproductive aggregation

do areas of upwelling have efficient energy transfer from level to level in its food chain?

yes, about 20% of the energy in a level is transferred to the next level -there are very few levels in the food chain in these areas because phytoplankton are so big, so they can be directly fed on by intermediary fish like anchovies, and then whales and predatory fish can directly pray on those smaller fish -Si, Fe, PO3, NO3 are all supplied by upwelling → diatoms are taking advantage of these nutrients with this short food chain, there's nothing in size between phytoplankton and anchovy -(intermediary fish) → creates lots of waste/excess organic matter in these small food chains → this excess matter sinks and is exported into the deep ocean → it doesn't matter that food and nutrients are being lost because there's lots of it -CO2 from the atmosphere in shallow ocean water is getting taken up, put into food, and exported to the deep ocean

how does the seasonal mixing of nutrients in the photic zone enable phytoplankton to overcome the problem of nutrients and light not often being in the same areas?

-WINTER: deep mixing = high nutrient concentrations in winter, but productivity is low because phytoplankton are mixed too deep and light is limited by the shorter length of the day -SPRING: increasing length of daylight + abundant nutrients (not used during the winter) + warming and shallowing of mixed layer (above the pycnocline) generates a spring phytoplankton bloom in April and May -SUMMER: plankton bloom rapidly depletes nutrients in the shallow mixed layer; zooplankton population also grows in response to phytoplankton bloom, with a balance achieved between low-level plant production and animal consumption through the summer -FALL: as surface waters cool and winds increase, pycnocline weakens and turns over, there's an increase in nutrients which commonly spawns a fall plankton bloom → typically not as big as spring bloom because days are getting shorter and temperature is getting colder

how does light level impact plants' ability to photosynthesize?

-at high light levels, plants can be overwhelmed by the amount of energy they're receiving -they can adjust to high light given time, but plankton can't control exactly where they are in the water column, so they're adapted to the average conditions → they're putting enough energy into making chlorophyll and photosynthesis for the average conditions that they'll experience → this means sometimes they will have a surplus of nutrients and sometimes they won't have enough

late Ordovician period environmental characteristics

-at this time, the area north of the tropics was almost entirely ocean → opposite of today's world most of the world's land was collected into the southern supercontinent Gondwana, and much of it was submerged underwater -from the Early to Middle Ordovician, the earth experienced a milder climate in which the weather was warm and the atmosphere contained a lot of moisture -however, Gondwana shifted towards the South Pole during the Late Ordovician, allowing massive glaciers to form and causing sea level to drop and shallow seas to drain

biomass of ocean plants vs. biomass of land plants

-biomass = amt. of plant material in an environment -biomass of ocean plants = 1-2 billion tons of plant material -biomass of land plants = 600-1000 billion tons of plant material -ocean plants have significantly less biomass than land plants, but are able to produce about the same amt. of carbon

what's the difference between the habitats of brachiopods and clams?

-brachiopods lived in the water column in the Ordovician period, while most clams lived in the mud -brachiopods had the advantage because the food was drifting around them and it was relatively easy to get -clams had to put a lot of effort into pumping fluid through its body because it wasn't just sitting up in the current and flowing by

what's the difference between where brachiopods and clams can be found nowadays?

-brachiopods still exist today but are very rarely found as seashells on the beach -now, clams and their relatives cover 98% of all the biomass in this area, and brachiopods are entirely restricted and localized to beach -many brachiopods are found in the Red Sea because it's deprived of many nutrients and food -however, in ancient TN, they were very common and far outnumbered the fossil clams and snails living in the sea

what's the difference between the shells of brachiopods and clams?

-brachiopods: two shells that clamp together are different shells; each one is bilaterally symmetrical -clams: two shells are the same, but they aren't bilaterally symmetrical

what are some marine organisms that are not built for speed, and how have they adapted to not need speed to survive?

-burrfish: inflates if a fish grabs it in its mouth → becomes spiny so predators immediately spit it out -seahorse: have highly modified skeletons comprised of fused, bony plates → not especially edible; because of this, they have very few predators when they're adults -boxfish: has hard exoskeleton made of fused, bony plates → not a meal choice for predators; fixed mouth serves as an effective suction pump to catch prey; delicate fins are useful for maneuvering through tight spaces; many similar fish include seahorses and others with fused bodies

distribution of biogenous sediments

-carbonate sediments are formed almost everywhere, but they dissolve where deep-ocean waters are too acidic → this mostly happens in old water; there are some areas of the Atlantic where they dissolve due to temperature and pressure, but the much larger area where these sediments are absent is in the Pacific Ocean -silica sediments are only found in nutrient-rich upwelling regions because Si is rare in ocean water and requires upwelling to deliver a continuous supply -clays are the "default" sediment type; they are almost everywhere, and are concentrated where there are no siliceous or carbonate sediments; most clays are delivered by winds from desert regions

primary production in the ocean

-carried out by microscopic, single-celled plants: phytoplankton -phytoplankton are responsible for about 40% of global productivity, but only about 1% of total plant biomass -light penetrates the surface water, but nutrients that plants need are concentrated below the pycnocline where there's no photosynthesis occurring -99% of ocean productivity (about ½ of world productivity) occurs in <20% of the ocean, specifically along coasts and at upwelling zones; so what, if anything, do coasts and upwelling zones have in common, as related to primary productivity? → nutrients!; in upwelling zones, water is drawn up from the deep ocean and into the light zone; off the coast, the main supply of nutrients comes from the land (such as from river runoff and groundwater) -the reason for this very uneven distribution of food production is that most places in the oceans do not have both adequate light AND sufficient nutrients; these two requirements all vary through time (seasons) as well, so plankton vary in both time and space (hence the need for much marine life to constantly move in search of food)

buoyancy gas chambers

-cephalopods used to have big shells → as organism grew, it kept adding chambers in its shell connected by a tube → chambered nautilus could pump water or gas into a chamber to change its buoyancy -this is how organisms could have big shells while changing their weight or density -most of these organisms don't have an external shell anymore, but they still have an evolutionary trait of their shell internally -this shell is much smaller now which means these organisms can move quickly

sediment size and settling velocity

-clay — smallest sediment size with smallest settling velocity -silt — diameter is 10x bigger than clay; settling velocity is 100x faster than clay -sand — diameter is 100x bigger than clay; settling velocity is 10,000x faster than clay

biological environmental factors requiring adaptation

-competition (nutrients, food, space) -predation — must avoid being eaten -disease and parasites

how does retreating sea ice that exposes nutrients stored through the winter enable phytoplankton to overcome the problem of nutrients and light not often being in the same areas?

-cover of sea ice retreats with spring melting → exposes surface waters to light -phytoplankton are also released from ice → known as "seed bloom" -phytoplankton are held close to the surface (in high light) by low salinity (low density) melted water from the sea ice -after some time (weeks to months), depleted nutrients and mixing end the bloom -highest chlorophyll concentrations follow the retreating ice edge

how does the anatomy of a fish enable it to swim?

-fish have back and forth motion of moving their bodies because they have braided muscle tissue across their backs → allows fish to very efficiently pull back and forth to create thrust needed to move the fish -alternate contraction and relaxation of the myomeres sends a wave of body curvature back along the body to produce a forward thrust

mass extinction that ended the Ordovician period

-geological setting: the Ordovician period was an era of global diversification of animal and plant species; as in the Cambrian, life in the Ordovician largely continued to be restricted to the seas -species affected: second most devastating extinction to marine communities in earth history; caused the disappearance of one third of all brachiopod and bryozoan families; more than one hundred families of marine invertebrates perished in this extinction

what caused the Ordovician mass extinction?

-glaciation and sea-level lowering -Ordovician mass extinction has been linked to glaciation of the continent Gondwana, with evidence for the glaciation represented by glacial deposits on the formerly connected continents of Africa, South America, and India -when the Gondwanan continent passed over the south pole in the Ordovician, global climatic cooling occurred to such a degree that it induced large-scale continental glaciation; the formation of continental ice sheets caused a worldwide lowering of sea level as large amounts of water became tied up in ice sheets -this lowered the sea-level and exposed the world's shallow seas and continental margins and, in conjunction with the cooling caused by glaciation itself, drastically reduced habitats for shallow-water tropical organisms leading to the mass extinction

truncated/forked caudal fins

-good for acceleration -most of these tail fins tend to be fairly stiff found on ambush predators that need to be able to accelerate really quickly to get their prey -truncated ex: salmon, pike -forked ex: herring, perch

rounded caudal fins

-good for maneuverability -most fish that have this rounded tail fin can move the individual bones in the tail → makes them very mobile and helps them to maneuver through tight spaces -ex: flounder, butterfly fish

lunated caudal fins

-good for speed -efficient way to maintain high speed for cruising in the open water → good for predatory fish even stiffer fins than truncated/forked -ex: tuna, mackerel

what problems arise from 99% of productivity occurring in less than 20% of the ocean?

-half of the food that is produced along the continental coasts which is where people are → it's easy for people to overfish the oceans -risk to ecosystems: any change in coastal zones or limited upwelling areas can have a profound impacts on their livelihood

form and function of great white shark

-has a streamlined body to reduce total drag -keeled caudal peduncle for efficient propulsion -broad cutting teeth on upper jaw; narrow grasping teeth on lower jaw -mates every other year; females reproduce at age 12-16 years → populations of organisms at the top of the food chain are susceptible to things that reduce population (like overfishing, etc.) -gives live birth (2-10 5 ft pups)

why do reef fish rarely use their caudal fins, and why do they use instead? what other other fins that fish can use, and what are the advantages to using these fins?

-if fish are swimming on reefs, one burst of their tail fin would send them crashing into an object; they use their pectoral (side) fins instead -using pectoral fins allows fish to move forward and backward in a short amt. of time and gives the fish a lot more control over their motion -some fish use their dorsal (back) and anal fins when moving through the open water or to move through restricted spaces

how does upwelling that provides a persistent supply of nutrients from the deep enable phytoplankton to overcome the problem of nutrients and light not often being in the same areas?

-important upwelling locations include: eastern boundaries of major ocean basins (California, Peru, N & S Africa); Arabian Sea — driven by seasonal Indian monsoon; equatorial Pacific and Atlantic; Antarctic Divergence -rate of upwelling and productivity is influenced by: strength of the driving winds; vertical structure (stratification) of the water column — mainly the strength and depth of the thermocline → controls how much energy is required to draw up the source water; ocean bottom topography — canyons, shelf, slope → can locally enhance or inhibit upwelling; large-scale current structure

why are the oceans around the poles able to be so productive in the spring months?

-in the southern ocean and northern oceans there's not much of a thermocline, so it's easy to mix deep waters up to the surface -with all the dark months, no nutrients are getting used → nutrients build up during the wintertime and in the springtime when there are 24 hours of light, southern and northern oceans can become extremely productive

carbonate-shell produced biogenous sediment

-includes coccoliths -you would think they'd accumulate everywhere because CaCO3 exists everywhere in the oceans -however, the carbonate ultimately comes from carbonic acid: if you build up the amt. of acid in the oceans, it dissolves the calcium carbonate -below the compensation depth, calcium carbonate shells dissolve because of lower temperature, high pressure, high CO2, and low pH (more acidic) → no record from the deep ocean that these organisms ever lived up there -Ca and CO are abundant in seawater, so carbonate shells are formed everywhere; dissolves easily in the deep ocean, esp. in Pacific Ocean

what is the main problem that limits how much phytoplankton can photosynthesize?

-light is near the surface and decreases exponentially with depth and nutrients are low in the surface ocean and increase with depth (they are prevented from mixing across the thermocline/pycnocline) → phytoplankton need both of these things to photosynthesize -SO, the location and magnitude of phytoplankton biomass (primary productivity) is dependent on a trade-off between light availability and nutrient flux

habitat classifications

-location in the water column: benthic (bottom dwelling) or pelagic (water-column dwelling) -relationship to sunlight: photic zone or aphotic zone -type of marine habitat: estuarine (interface between fresh and ocean water that occurs at the coast), intertidal, neritic or coastal, oceanic (open ocean water)

life in the Ordovician period (490-443 mya)

-major ecological developments include a four-fold increase in the diversity of marine animal families -among these new organisms, the Ordovician is best known for its diverse marine invertebrates, including trilobites, brachiopods, crinoids, molluscs (especially gastropods — snails), and cephalopods (early squids) -the Ordovician is also marked by the first appearance of vertebrates (animals with backbones, spines, and brains) → these were primitive fish -one of the most notable Ordovician firsts is invasion of the land by primitive plants and fungi → there are the first multicellular organisms to colonize the earth's land surface -the end of the Ordovician period witnessed one of the strongest ice ages in the last 600 million years and triggered the Ordovician-Silurian extinction event, which rendered extinct 50% of all animal groups on Earth

daily vertical migration

-many marine organisms undertake a daily vertical migration to deeper, darker parts of the ocean to avoid becoming prey → at night, they feed in the highly productive surface waters under covers of darkness to protect themselves from being seen by predators -food vs. safety: daily migration of zooplankton into the photic zone at night to graze on phytoplankton → reverse migration into the aphotic zone during the day to avoid predation

how can phytoplankton reduce atmospheric CO2 levels (and thus possibly mitigate CO2 from fossil fuel burning)?

-marine and atmospheric CO2 is converted to organic carbon during photosynthesis -phytoplankton store this organic carbon in their cells -when phytoplankton die or are consumed, they may sink to the bottom of the ocean -this mechanism "stores" carbon in the deep ocean big remaining questions are: (1) how much carbon actually gets "exported" out of the photic zone and (2) how much of the carbon that does reach the seafloor is buried before being decomposed by bacteria (which re-releases the CO2)?

rates of sediment accumulation in the oceans

-millimeters of sediment per 1 year along the coast — where rivers are delivering sediment, so sediment accumulates quicker → how continent-building occurs -millimeters of sediment per 100 years on the shelf -millimeters of sediment per 1000 years in the open ocean

how are ocean communities able to produce approximately the same amount of carbon as land communities with significantly less plant material (biomass)?

-most of the biomass in a plant or a tree is in the structure that holds it up → plants on land have to compete for light, so a lot of the energy that is produced by land plants goes into the structure they need to compete for light → the leaves of the tree are the parts that are edible, but lots of energy is put into the wood biomass to have it grow and compete for light -plankton is all photosynthetic and entirely edible → the energy of the phytoplankton doesn't have to go into building a tree structure → it only goes into the photosynthetic part so it can produce more food → these cells multiply and can produce offspring -plankton is the equivalent of the most productive part of a land plant, but it is all capped up in a single organism → much more efficient at producing edible biomass

silica-shell produced biogenous sediment

-mostly diatoms -typically, they live in sunlit surface waters → however, if there isn't constant upwelling there are very few of them, and whichever ones that do live there sink down and disappear → leaves no record of silica-producing organisms -in areas of upwelling, there are many of them on the surface because of high productivity so there are many of them dying and sinking down → their shells accumulate and form siliceous ooze -with time, where these silica-producing shells accumulate in the deep ocean changes as plate tectonics move -Si is in very low concentration in seawater, so it's only available locally in oceans (mainly near coasts and upwelling areas, esp. rivers)

differences between the geography of the three regions of TN

-western TN has floodplain soils and is largely dominated by agriculture → is the youngest part of TN (includes MS River Valley) -middle TN has rolling hills and lots of pasture land more so than agriculture land → oldest part of TN with cambrian and ordovician rocks -eastern TN has Appalachian mountains where there's a lot of industry from metal ores, etc.

the Antarctic Icefish (15 species) is the world's ONLY vertebrate to lack hemoglobin in its blood → their rate of oxygen uptake is thus much less efficient, so why did they evolve this "disadvantage" and how have they adapted?

-needs/opportunities: iron is low in the oceans, but it's especially low in the Southern Ocean because there's no land nearby to provide wind-blown dust to the ocean; if there's limited iron, it would be advantageous for ice fish to not need iron in its bloodstream; the Southern Ocean is permanently cold and can hold more dissolved oxygen; reduced species diversity begun about 15 million years ago due to cooling and glaciation → once it became colder and had less iron, icefish were driven to evolve to take advantage of these new conditions -adaptations: low metabolism and ambush predator → both use less energy; larger heart and blood vessels to increase blood flow and oxygen transport

net ocean productivity vs. net land productivity

-net productivity = amt. of food that is produced in an environment -net ocean productivity = 35-50 billion tons of carbon per year -net land productivity = 50-70 billion tons of carbon per year -net productivity from ocean to land is approximately the same

what was on land during the Ordovician period?

-not much, but the very first complex organisms to colonize the land appear in the Ordovician -these plants are the liverworts and club mosses -typically small, usually 2-20 mm wide with individual plants less than 10 cm long -certain species may cover large patches of ground, rocks, or any other reasonably firm substrate -today they are distributed globally in almost every available habitat, most often in humid locations although there are desert and arctic species as well -there were also symbiotic fungi that help yield nutrients from rocks

how does nutrient availability change with depth in the ocean?

-nutrients are low in the surface ocean because plants are rapidly using them up, but as soon as you get through the photic zone, they're much higher -all you need is a little bit of mixing in that zone to drive lots of nutrients

phytoplankton reproduction

-occurs by simple cell division (mitosis), but produces a "naked" cell, which upon release begins to grow its own "shell" (called tests or frustules for phytoplankton) -populations can double in a matter of just a few hours or a few days, which allows them to quickly respond to changes in nutrient availability and other environmental conditions

how do high levels of CO2 below the compensation depth make it so calcium carbonate shells dissolve?

-ocean around Greenland forms North Atlantic Deep Water, and around Antarctica is the Antarctic bottom water -NADW flows down South, ABW spills up into Atlantic and Pacific Oceans → this means N. Pacific Oceans are at the end of the circulation route → takes a long time (about 1000 years) for that water to get up into the Pacific Ocean -there's initially oxygen in this water, but the organisms in the deep ocean take up the oxygen and organic matter and respire it for energy, where the byproduct is CO2 -along the deep ocean flow path, areas that are at the very end that take about 1000 years to get to means that most of the oxygen has been used up and converted to carbon dioxide, which combines with water to form carbonic acid

why is there less species diversity in the open ocean (pelagic) compared to on the seabed (benthic)?

-of all the marine species, benthic species make up 98% and pelagic species make up 2% number of available ecological niches is greater in the benthic region than in the pelagic region -only a few organisms can swim quickly to protect themselves from predators in the open ocean in benthic habitats, things can live in the seabed and hide on the sea floor -there's also a more steady supply of food in the benthic region, as food tends to collect on the seabed after it is produced near the surface

why is there less species diversity in the oceans compared to on land?

-of all the world species, land species make up about 86% and marine species make up about 14% number of available ecological niches (i.e. diversity and connectedness of habitats, and life strategies) is greater on land than in the ocean -oceans are all connected to one another, and many of the organisms living in the ocean have to migrate between oceans to follow their food -on land, the continents are divided by ocean masses → only birds and insects can migrate from continent to continent, whereas plants and land animals can't easily move across these barriers → allows for each continent to have unique flora and fauna living there

how does oxygen availability change with depth in the ocean?

-oxygen is high in surface waters because 1) oxygen is exchanging with the atmosphere and 2) photosynthesis is taking place and producing oxygen -as soon as you get below the photic zone, oxygen drops off dramatically to oxygen minimum zone; there are huge areas of intermediate oceans that are devoid of life because there's no oxygen -oxygen increases as you go deeper because of deep-ocean circulation: cold, nutrient-rich, oxygen-rich surface waters in Greenland and Iceland Seas and near Antarctica get cold enough to sink down in the deep ocean to bathe these waters in oxygen; without this mechanism, oxygen would decline and stay low because there would be no other source of oxygen; deep-ocean circulation driven by the fact that high latitude waters get very cold → if high latitude temperatures increase by 10º, the water will be warmer and less dense, so it won't sink as much or as fast → slows down deep-ocean circulation rate and the delivery of oxygen to the deep ocean; during globally warm climate periods in earth's history, the world's deep oceans run out of oxygen and everything in the deep sea dies → these are times of mass extinction

what are the impacts that humans have had on the ecosystem by overfishing and depleting the fish from the oceans?

-research has shown that human fishing pressure has driven the active evolution of many of these organisms -typically, ecosystems would be dominated by the largest and oldest individuals → many would take many years to mature, but to survive, now they have to be able to reproduce much more quickly to sustain their populations -for the last few decades, most of the world's fisheries are in a depleted state: takes more and more effort to get less fish; this results in many fisheries collapsing because it's not economically advantageous

physical environmental factors requiring adaptation

-salinity, temperature, light -dissolved oxygen concentration: amt. of oxygen dissolved in water is about 1 million times less than what's in air → oxygen can get very low in the water

examples of adaptation

-salinity: osmoconformers and osmoregulators; osmosis vs. active transport vs. diffusion -light: photosynthesis vs. respiration = compensation depth (depth where photosynthesis is just sufficient to balance night-time respiration demands) -predation: diel vertical migration of zooplankton; migrate into the photic zone at night to feed on phytoplankton, then return to a depth below light penetration during the day to avoid being eaten -morphology: surface, form, and turbulent drag; the shape of fast, swimming fish is optimized to reduce drag in the water

how do phytoplankton overcome the problem of nutrients and light not often being in the same areas?

-seasonal mixing of nutrients into the photic zone -retreating sea ice that exposes nutrients stored through the winter -upwelling that provides a persistent supply of nutrients from the deep

do bigger or smaller plankton have an advantage in terms of their nutrient uptake and energy demand?

-smaller plankton do -surface area to volume ratio compares size of the cell and how much energy it needs vs. the surface area in which nutrients can diffuse into the body smaller phytoplankton have a greater surface area to volume ratio -they have a smaller energy demand and a greater surface area, so as they crank out photosynthesis, things are diffusing into their cell faster than in bigger phytoplankton -they have a faster diffusion rate

vertebrates in the Ordovician period

-some of the earliest vertebrates appear in the Ordovician seas -these were armored fish informally called ostracoderms, meaning "shell skin" -they had large bony shields on their head and platelike scales covering the tail -they were jawless and had only a slit-like mouth for slurping up invertebrates -because of this, they couldn't chase and hunt things down (couldn't be predator) and couldn't defend themselves from the main predator, the cephalopods -how to eat with no jaws: lamprey sucks itself onto a fish and twists itself back and forth with grinding "teeth"; hagfish uses muscles to wiggle two plates that have grinding "teeth"; many high-end leather products are made from hagfish skin; they need little oxygen and little energy -ostracoderms didn't survive, but are part of the main ancestry of ALL vertebrate animals; bony fish and jawed vertebrates evolved out of them as a separate branch; hagfish and lampreys evolved in Cambrian and Ordovician period and have survived all the way to today

stable isotopes in the ocean

-stable isotopes in the oceans vary with environmental conditions -isotopes are forms of an element that have different numbers of neutrons → their chemical properties are nearly the same, but their mass differs -in oceanographic research, one of the mostly widely used pairs of stable isotopes is 16O and 18O, with masses of 16 and 18 atomic mass units, respectively -kinetic fractionation: due to their larger masses, heavier isotopes tend to react somewhat more slowly than lighter isotopes of the same element; so, as oxygen bearing elements (like water H2O and carbonate CO3) are formed and transported through the environment, they become "fractionated" (i.e. the ratio of 16O:18O abundance changes) -light oxygen is preferentially taken out of the water, while heavy oxygen is preferentially left behind → even though you're taking out more, it's just coming right back into the system through the water cycle; however, that evaporated water comes out and could fall as snow which doesn't melt and starts to form a glacier → as ice sheets and glaciers expand and contract, ratio of 16O:18O changes: when ice sheets are big, oceans have more 18O because all of the 16O has been transferred to the ice of the glaciers -processes that commonly fractionate oxygen isotopes include: evaporation, precipitation, biological activity, changes in temperature → such variations might be recorded in ice/glaciers, organic matter, shells, cave deposits

what special features make the Tuna the ultimate fast-cruising fish?

-streamlined body optimized to reduce total drag -small and smooth scales -non-bulging eyes -fins retractable and recessed (even dorsal fin has a groove to recess into) -turbulence-reducing finlets: when a fish is swimming, the back of the fish is moving the water back and forth creating turbulence; finlets are there to reduce turbulent energy and allow for the fish to move quickly despite the turbulence -strengthened, keeled caudal peduncle: tail fin = caudal fin; area that attaches fin to the fish = peduncle; peduncle is skinny from the side, but wide from the top -tendons move tail, not individual muscles: muscles are just pulling tendons that go out to the tail, so tail can be small, compact, and efficient -tail is slender but stiff (lightweight) -efficient blood transport to muscles (temp and oxygen) — must keep active: because most fish are cold-blooded, they must conserve their heat in the interior of the body and rest a lot; tuna don't rest → they're constantly swimming, so their muscles have to do a lot of work → their muscle tissue needs a constant supply of blood; muscles work more efficiently when they're warm; tunas have a well-developed blood network that keeps their muscles active and warm

what's the difference between the internal structures of brachiopods and clams?

-the clam has a gut system that goes through the mouth and regulates inputs and outputs separately → pretty typical of what you would think of in complex organisms -brachiopod has one opening where food goes in and waste comes out -clam has the advantage in terms of taking in food and getting energy out of it → whatever brachiopod takes in has to be digested and taken back out → can't take in new stuff until the old stuff is gone -brachiopod had the advantage back in the Ordovician period because its digestion required less energy → had much slower metabolism than clam, but there wasn't a lot of food to be had in the first place; clams were restricted to areas that had high food production, which were very localized in the Ordovician; clams couldn't outcompete brachiopods which were better adapted to a food poor ecosystem

types of phytoplankton and where they occur

-two main types of phytoplankton are those that make their "shells" out of silica or calcium carbonate -silica is relatively rare in the oceans, and only found in significant quantities in upwelling zones (from the deep ocean) and near coasts (from river input) -calcium and carbonate, by comparison, are relatively abundant in the world's oceans, and so phytoplankton that make their shells out of CaCO3 are widespread across the oceans; however, many of these areas lack the nutrients for rapid growth, so the abundance is relatively low even where they are found -the most common silica phytoplankton are diatoms (cold-water coasts and polar upwelling) and dinoflagellates (warm-water coasts and equatorial upwelling) -the most common calcium carbonate phytoplankton are coccolithophores; they are found mostly in warm, open ocean environments

plankton size and food web structure

-where nutrients are limited and plankton are small, there tends to be complex food webs of many different organisms that effectively recycle organic matter (food); in this case, if there are more types of organisms sharing a relatively limited amt. of food, then none of these organisms can be too abundant, and so nutrient-poor areas tend to have complex food webs that have great diversity in organisms but low size and numbers of each species -where nutrients are abundant and plankton are large, there tends to be simple food webs, with shrimp or fish feeding directly on the plankton, and then predatory fish and mammals feeding directly on the plankton-eating shrimp and small fish; this is a simple food web with low animal diversity, but abundant and large organisms

nutrients and plankton size

-where nutrients are rare, phytoplankton remain small and are less nutritious (typical for open ocean ecosystems, dominated by calcium-carbonate phytoplankton) -conversely, where nutrients are more abundant, phytoplankton tend to be larger and more nutritious (typical for upwelling and coastal settings, dominated by the silica-shelled diatoms) -these small vs. large plankton are both adapted to their environment and control the nature of the local food web -small plankton have a higher surface area to volume ratio, meaning that they can more effectively uptake nutrients into their bodies, which is advantageous in areas with limited nutrients -conversely, large plankton have a lower surface area to volume ratio, and thus cannot take up nutrients as effectively; however, in upwelling and coastal zones, nutrients are relatively abundant, and so it is more important to be bigger and healthier

coccolithophores

a microscopic plankton form of algae encased by a covering composed of calcareous discs (coccoliths) -their outer shells are made out of calcium carbonate -found in warm, tropical to subtropical waters -coccolith shells form the White Cliffs of Dover — chalk deposits

trophic level

a nourishment level in a food chain; comprises organisms at the same position in a food chain, beginning with primary producers and upwards to grazers/herbivores and carnivores -a trophic pyramid conveys both the trophic level and the approximate biomass at any given level -at each trophic transfer, there's a loss of energy (to decomposition, heat, etc.), and only a fraction of it is transferred to the next level, so by the time you get to the top carnivores, there's only a fraction of the energy that was originally available to the ecosystem; this is why top carnivores are less abundant than organisms at lower tiers of the pyramid -a typical efficiency for trophic energy transfer from one level to the next is 10% >> the other 90% is used for survival and reproduction; in very efficient food webs, trophic transfer can be 15-20% (i.e. upwelling and coastal zones)

habitat

a place where a particular plant or animal lives -generally refers to a smaller area than an environment -organisms adapt to the specific conditions in which they live

diatoms

a plankton that is a member of the class Bacillariophycaea of algae that possesses a wall of overlapping silica valves -outer shells are made of silica — silica is rare in the oceans but doesn't tend to dissolve once it's part of a shell -found along coasts and antarctic upwelling — the only way diatoms can survive is with a constant resupply of nutrients → if silica is rare, they must have a consistent supply of silica in order to live and reproduce, and silica is only found along the coasts and where antarctic upwelling occurs; these phytoplankton produce the vast majority of nutrients because 99% of ocean productivity occurs along the coasts and in upwelling zones, which is where they live -very diverse in their shapes and sizes

viscosity

a property of a substance to offer resistance to flow caused by internal friction; a measure of how easily a fluid deforms (moves) -higher viscosity means that the fluid is "thick" and deforms slowly; low viscosity means that the fluid is "thin" and deforms quickly -viscosity varies with temperature: colder temperatures = higher viscosity (deforms slowly); warmer temperatures = lower viscosity (deforms quickly)

hemoglobin

an iron-containing protein that transports oxygen in the red blood cells of (almost) all vertebrates

autotroph

an organism that is able to manufacture its own food supply -photosynthesis is the main autotrophic pathway for eukaryotes (i.e. plants), but for bacteria and archaea there are many different energy pathways

heterotroph

an organism that requires an external food supply -respiration is the main heterotrophic pathway for eukaryotes (i.e. animals), but for bacteria and archaea there are many different energy pathways

sediment

any loose particle of inorganic and organic matter (eroded rock, plant matter, fossils, shells, etc.) sediments tend to collect or deposit in basins (low-lying, relatively calm areas) -they preserve records of climate, chemistry, biology, and physical conditions on Earth -they supply nutrients to the oceans -they host most oil, gas, and mineral reserves -they control the fate of many environmental pollutants

osmoconformers

marine organisms that maintain an internal environment in which the osmotic pressure of their cells is equal to that of their surrounding environment -salinity in the body = salinity in the water -diffusion and osmosis take place naturally -simple organisms are osmoconformers, including all benthic invertebrates → they're highly adaptable, which is why they still exist after millions of years

trophic efficiency: transfer of energy

nutrients are pretty rare in the open ocean, but they exist in patches → can come from storms (due to their rotation in winds driving water away from the surface and upwelling nutrient-rich cold water from the deep ocean), upwelling, eddies -in an environment where energy, nutrients, and food are rare, the ecosystem is set up to not waste anything → organisms are set up to feed on feces so all energy losses are conserved → however, this is not efficient because it takes a long time to get to the top predators, making these predators pretty rare -on the coast, there's an abundance of nutrients from river transporting water -in upwelling areas, the SE trade winds blow across the equator and the two directions of Coriolis drive water away from the equator and pulling it up from the deep → constant supply of nutrients coming in in the open ocean, there are not as many nutrients → these environments have more diversity and a more complex food web than environments that have lots of nutrients -in these areas, it doesn't matter if there's waste levels because there are more nutrients, so things don't have be conserved as much -these pyramids have fewer levels because of this -phytoplankton in these areas are much bigger than those in the open ocean → they're big enough so that upper-tier organisms can feed directly on them, giving them less levels on their pyramid -complex food webs in the open ocean conserve nutrients better than more simple food webs off the coast and in upwelling areas, but more harvestable organisms are found in simple food webs

eukarya

one of the three major domains of life -includes (mostly) single-celled or multi-cellular organisms whose cells usually contain a distinct, membrane-bound nucleus -scientists are finding that eukaryotic life is actually pretty well-constrained in terms of its genetic diversity, and the other two groups are much more diverse -main component of eukaryotes = DNA eukaryotes: mostly unicellular, but also many complex multicellular organisms (all plants, animals, fungi) -in eukaryotes, all the different parts of the cells are partitioned within the cell wall, so they can be targeted to the task at hand and evolve more efficient, specialized structures -different groups have evolved to take advantage of most ecological niches → organisms compete within these ecological niches which creates diversity (from trophic role and habitat)

lithogenous sediment

sediment composed of mineral grains derived from the weathering of rock material and transported to the ocean by various mechanisms of transport, including running water, gravity, the movement of ice, and wind -sources: rivers, coastal erosion, landslides, glaciers, turbidity currents -of all the sediment that is delivered to the oceans, 80% comes from rivers, 2% comes from glaciers and ice sheets, and really small amts. of sediment come from wind-blown dust, coastal erosion, and volcanic debris → rivers and glaciers are responsible for building out the continents on the edges of the ocean, but wind blown dust and volcanic debris provide the most significant amt. of nutrients to the oceans -rivers and glaciers tend to transport course sediment that gets stuck on the continental shelf; plants need nutrients to produce food in the ocean, but if it's getting trapped near the coast, the nutrients' impact is limited -wind-blown dust and volcanic ash are put up into the atmosphere and blown in the wind → this is why they're the main sources of nutrients in the ocean

cosmogenic sediments

sediment derived from outer space -sources: space dust, meteors -includes ash, shocked quartz, and tecktites formed by collisions with meteorites

hydrogenic sediments

sediment that forms from precipitation from ocean water or ion exchange between existing sediment and ocean water -sources: precipitation of dissolved materials directly from seawater due to chemical reactions -hydrothermal deposits: deep-sea vents release superheated water that has been circulated through ocean crust and near the mantle; so, vent fluids are rich in dissolved minerals metal-rich sediments precipitate when vent fluid mixes with cold ocean water -evaporite salts: Mediterranean Sea and Gulf of Mexico are large seas only loosely connected to open ocean and are underlain by thick salt deposits; about 5.5 million years ago, Med. Sea dried several times leaving behind salt deposits several km. thick; this sucked out salt from the ocean, making salinity lower, which meant ocean water froze more easily because it had lower salinity; this local evaporation actually caused global cooling because sea ice at the poles formed more easily which reflected more light and cooled the global climate

do simple organisms or complex organisms have greater physiological diversity?

simple organisms

do simple organisms or complex organisms have more energy diversity?

simple organisms (bacteria and archaea) -these organisms have varied energy pathways and evolve to take advantage of unique energy resources -results in them having greater physiological diversity than complex organisms

dinoflagellates

single-celled microscopic planktonic organism that may possess chlorophyll and belong to the phylum Pyrrophyta (autotrophic) or may ingest food and belong to the class Mastigophora of the phylum Protozoa (heterotrophic) -outer shells are made of silica -found in equatorial upwelling zones -very diverse in their shapes and sizes

compensation depth

the depth at which net photosynthesis becomes zero (where respiration rate = photosynthesis rate) -amt. of energy that plant needs is exactly equal to the amt. of energy that the plant produces at this point -when phytoplankton sit above that depth, they're producing more food than they need → this is extra energy that can go into reproduction -when phytoplankton sit below that depth, the rate of photosynthesis is still going, but the amt. of photosynthesis is less than the respiration rate → plankton don't die here, but they're losing mass because they're burning more energy than they're producing through photosynthesis -in the wintertime, the sun is lower and day length is shorter so there's less light, making the compensation depth shallower than it typically is → compensation depth will move up and down depending on the amt. of light that there is -compensation depth is greater in the open ocean (up to 100 m.) than near the shore due to increased turbidity that limits light penetration in coastal regions

osmoregulation

the maintenance of constant osmotic pressure in the fluids of an organism by the control of water and salt concentrations -single-celled organisms need nutrients from the water → because it's a single cell and things can diffuse across the boundary, most of these organisms get their nutrient supply through diffusion; nutrient materials diffuse in, waste products diffuse out; the organism doesn't have to use a lot of energy for this exchange to occur; during upwelling events, all the extra nutrients in the water start diffusing into the plant at a higher rate -complex organisms have a salt concentration of about 18%, whereas oceans have a concentration of about 35%; skin is porous → marine fish are constantly fighting dehydration because the osmotic pressure is trying to drive water out of the fish, thereby increasing salt concentration within the fish; water loss by osmosis must continuously be offset by other processes: salt is excreted via gills, minimal water loss in urine → water and salt is gained by drinking; marine animals put a lot of energy into balancing this osmotic process

photic zone

the upper ocean in which the presence of solar radiation is detectable; includes the euphotic zone -light penetrates to a max of 150 meters in this zone

what was the result of there not being organisms living on land in the Ordovician period?

there weren't soils on land