Chemical Oceanography - PowerPoint Presentation

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Chemical Oceanography

Marine Science Unit 4:

umassmarine.netSlide2

Marine Science: Chemical Oceanography Day 1 – Water Structure and Properties

Objectives:Explain the structure of a water molecule.What is a polar molecule?What “special” properties does water have because it is a polar molecule?

Why does ice float? Why is that important to Earth?Slide3

Chemical OceanographyThe study of the chemical reactions that occur in sea water

s

tudydiscussions.com Slide4

Water Structure

Water is made up of two elementsHydrogenOxygen

The chemical symbol for water is H2O

This means that each molecule of water is composed of two hydrogen atoms and one oxygen atom.

Water Boy clip:

http://www.safeshare.tv/w/cAKmYDwOFS

ehe.osu.eduSlide5

Water Structure

The hydrogen atoms are bonded to the oxygen atom in water

The type of bond that holds these atoms together is a covalent bond.Covalent Bond: Type of chemical bond that involves the sharing of electrons between two or more atoms

medicalsciencenavigator.comSlide6
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Polarity of WaterWater is a

polar molecule because it has an uneven distribution of chargesThe oxygen atom attracts the shared electrons close towards its large nucleus – making it slightly more negative (-)The two hydrogen atoms have more protons than electrons – making them slightly positive (+)

cultivatecuriosity.com

teachingphysics.wordpress.comSlide8

Water Molecules form Hydrogen Bonds

Water’s polarity allows it to bond with many other molecules – including itselfHydrogen Bonds form between water molecules because the slightly positive hydrogen end of one water molecule is attracted to the slightly negative oxygen end of another water moleculeHydrogen bonds are much weaker than covalent bonds

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http://programs.northlandcollege.edu/biology/biology1111/animations/hydrogenbonds.html

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Why does ice float? How is it important to the thermal conditions on Earth?Slide11
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Properties of WaterDue to its polarity, water has special properties…

Water as a liquidCohesion/AdhesionViscositySurface TensionIce Floats

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Liquid WaterWater is liquid at room temperature because hydrogen bonds hold the molecules together

More energy (heat) is needed to break the hydrogen bonds to turn water from a liquid to a gas (water vapor/steam)

whatscookingamerica.netSlide14

Cohesion and AdhesionCohesion

Water molecules stick to each otherAdhesionWater sticks to other materialsDue to its polarity, the partial positive and negative charges of water molecules are attracted to positive and negative forces of other substances

ga.water.usgs.gov

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Viscosity

The tendency of a fluid (gas or liquid) to resist flowMost fluids change viscosity as the temperature changesHydrogen bonds hold water molecules together, they make water more viscous As water cools, the viscosity rises more than other liquids because the hydrogen bonds resists the tendency to move molecules apart

This is important for aquatic organisms because it affects the amount of energy they expend:For floating/drifting organisms like plankton need less energy to keep from sinkingFor swimming organisms because it requires them to use more energy to move through it

nationstates.netSlide18
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Surface Tension

Water’s resistance to objects penetrating its surfaceThe polar nature of water allows it to form a “skin”Caused by hydrogen bonds holding the water molecules togetherMany smaller animals use surface tension and weight distribution to “walk on water”

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Ice Floats?

Most substances become dense and sink as they cool and turn from liquid to solidMost substances lose density as they heat and turn from liquid to gasWater also becomes less dense as it heats and becomes denser as it cools… but only to a certain pointAs water cools enough to turn from a liquid to a solid, the hydrogen bonds spread the molecules into a crystal structure that takes up more space than liquid water

With more volume, ice is less dense than water so it floatsThis property has a huge effect on EarthBy floating, ice insulates the water below, allowing to retain heat and remain a liquid – if ice sank the oceans would be entirely frozen or at least much colder – this would drastically change the Earth’s climate

gps.caltech.eduSlide24
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Marine Science: Chemical Oceanography Day 2 – Chemistry of Water

Objectives:What are the differences between solutions and mixtures?What is the “universal solvent”? Why?Slide26

Solutions and Mixtures in Water

What is a solution?When the molecules of one substance are evenly (homogenously) dispersed among molecules of another substance.Water is the universal solvent due to its polarity

Solvent: the substance that dissolves the soluteSolute: the substance that is dissolved in another

What is a

mixture

?

Two or more substances are closely intermingling , yet retain their individual characteristics

Ex. India ink in water = can be mixed together but if left alone ink settles out

water.me.vccs.eduSlide27

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Water as a Solvent

Salt dissolves in water due to water’s polarityWater’s polarity pulls apart/dissociates the salt crystals (NaCl)In the process, the dissociated sodium and chloride become charged particles/ions and are attracted to the positive hydrogen atoms and the negative oxygen atoms of water moleculesThese bonds tend to keep salt in the solution

elmhurst.edu

physicscentral.comSlide30

Water as a Solvent

Substances that do not separate into ions can still dissolve in water through other mechanismsEx. Sugar is not ionic but can dissolve in water when it is broken down into its individual molecules Because so many substances dissolve in water, it is known as the “universal solvent”A few substances do NOT dissolve in water…Non-polar substances like oil do not dissolve in water

This is why oil spills float on top of the water…Slide31

A Tasty Solution ActivitySlide32

Marine Science: Chemical Oceanography Day 3- Salinity

Objectives:What is salinity? What are the major sea salts?What are the colligative properties of seawater?What is the principle of constant proportions?

What are the most abundant chemicals in seawater?Where do sea salts come from?How do temperature and salinity affect seawater?What factors affect seawater pH?Slide33

Salts and Salinity

Salinity: The total quantity or concentration of all dissolved inorganic solids (ions) in seawater. Dissolved Salts: Any salt dissolved in seawater Salinity is expressed in parts per thousand (‰) because even very small variations are significantTo convert parts per thousand into percent you divide by 10, so that 35 ‰ = 3.5%How do scientists measure salinity?

Methods vary but usually involve the conduction of electricity

planet-science.comSlide34

Major Sea Salts

Only six elements and compounds comprise about 99% of sea salts:chloride (Cl-)sodium (Na+

)sulfur (SO4-2)

magnesium (Mg

+2

)

calcium (Ca

+2

)

potassium (K

+

)

The

chloride

ion makes up 55% of the salt in seawater.Slide35

©HRWSlide36

Why are the oceans salty?

Weathering/ErosionEvaporationHydrothermal VentsBiological ProcessesVolcanic ActivitySlide37

oceanclassrooms.com

Are the Oceans Getting Saltier?Slide38

Why are the oceans salty?

When it rains on land, some of the water dissolves minerals, like salt, in rocks. That water flows in rivers to the sea. It carries the minerals with it. When water evaporates back out of the ocean, it leaves the minerals behind. The minerals make sea water salty.

palomar.eduSlide39

Variations in Oceanic Salinity

The proportion of dissolved sea salts does not change, only the relative amount of waterThere is variation in specific areas:Mouth of River – near zeroRed Sea - 40 ‰Brackishwater (freshwater mixes with seawater in estuaries) - 0.6 ‰ to 30 ‰

Brine Water (areas with high evaporation and little inflow of freshwater or where salt domes dissolved on the seafloor – Gulf of Mexico) – Saturated or nearly saturated Slide40

Salinity of Ocean Water

©HRWSlide41

Colligative Properties of Seawater

Colligative Properties: The properties of a liquid that may be altered by the presence of a soluteThe strength of the colligative

properties depends on the quantity of soluteThe colligative properties of seawater are

:

Raised Boiling Point

– boiling point of seawater is slightly higher than pure fresh water

Decreased Freezing Temp

– freezing point of seawater is slightly lower than that of pure fresh water

Ability to Create Osmotic Pressure

– see next slide

Electrical Conductivity

– Salts act like conductors and conduct electricity

Decreased Heat Capacity

– It takes less heat to raise the temperature of seawater than to raise freshwater

Slowed Evaporation

– The attraction between salt ions and water keeps seawater from evaporating as fast as freshwaterSlide42

Ability to Create Osmotic Pressure

Osmosis: Movement of water through a semi-permeable membrane from areas of HIGH concentration to areas of LOW concentrationCrucial to many biological processes

sparknotes.com

http://www.youtube.com/watch?v=w3_8FSrqc-I

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Principle of Constant Proportions

Principle of Constant Proportions: Principle that the proportions of dissolved elements in seawater are constantOnly the amount of water (and therefore the salinity) changes Conservative Constituents: Dissolved Salts

No matter how much the salinity varies, the proportion of key elements and compounds don’t changeUseful b/c if you know the amount of one element, you can determine how much there is of others.Slide44

Dissolved Solids in Seawater

Besides hydrogen and oxygen (H2O) the most abundant chemicals in seawater are:Chloride 18.98 gSodium 10.56 gSulfate 2.65 gMagnesium 1.28 g

Bicarbonate 0.14 g Calcium 0.40 gPotassium 0.38 gOther 0.16 g

*Remember Average Salinity

is 35‰ = 3.5% = 35 gSlide45

Determining Salinity

Using the principle of constant proportions, if you know how much you have of one seawater chemical, you figure out the salinity.The formula for determining salinity is based on all the chloride compounds (not just sodium chloride) Salinity ‰ = 1.80655 x

chlorinity ‰Example: You have a seawater sample that tests 19.2 ‰ chlorinity – What is the salinity of this water sample?

Salinity ‰ = 1.80655 x 19.2 ‰

Salinity ‰ = 34.68 ‰

Likewise, when you know salinity you can determine

chlorinity

:

Example: You have a seawater sample that tests 34.68 ‰ salinity – What is the

chlorinity

of this water sample?

34.68 ‰ =1.80655 x

chlorinity

‰

19.2 ‰ =

chlorinity

‰ Slide46

Practice Using The Principle of Constant Proportions

Salinity ‰ = 1.80655 x chlorinity ‰

1. If the cholorinity of a seawater sample is 21.3g, what is the salinity?

2. If the salinity of seawater sample is 41.06g, what is the

chlorinity

?Slide47

Determining Salinity, Temperature, and Depth

Scientists measure salinity, temperature, and depth using special instruments and procedures:Salinometer: Determines the electrical conductivity of waterConductivity, Temperature, and Depth Sensor (CTD): Sensor that can be attached to a submersible or deployed by itself to profile temperature, depth and salinity. Data are transmitted to a ship/vessel

Temperature and salinity are used to determine density

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Salinity, Temperature, and Water Density

Most of the ocean’s surface has an average salinity of 35 ‰Waves, tides, and currents mix waters of varying salinity and make them more uniform – so, even surface salinity varies with the season, weather (especially rainfall and evaporation), and location (bays, semi-enclosed seas, and mouths of large rivers)Rainwater and water flowing from freshwater rivers lowers salinity while evaporation increases salinity

Salinity and temperature also vary by depthDensity differences cause water to separate into layersHigh density layers like beneath lower density layersWarmer, lower density surface waters are separated from cool, high density deep waters by the

thermocline

Thermocline

: The zone at which the temperature changes rapidly with depthSlide50

lincolninteractive.orgSlide51

Thermocline ActivitySlide52

Acidity and Alkalinity

Acidity and alkalinity are measured on the pH Scale.The pH scale measures the amount of positive hydrogen ions (H+) and negative hydroxide ions (OH-) in a liquid

Acid: A solution high in H+ ions is considered (0-7)Base

: A solution high in OH- ions is considered to be alkaline (7-14)

Increasingly Acidic

Increasingly BasicSlide53
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Acidity and Alkalinity

pH of Seawater:Pure seawater has a pH of 7 (7 is neutral)Typical seawater has a pH range of 7.8 – 8.3Carbon dioxide in seawater acts as a buffer and prevents changes in the pH of the ocean

nature.comSlide55

Carbon Compensate Depth

Although seawater pH is relatively stable it changes with depth b/c the amount of carbon dioxide varies by depthUpper Depths - generally 8.5 pH– warmer and have photosynthetic organisms with less CO2Middle Depths

- more carbon dioxide present from respiration of marine organisms – more acidic with lower pHLower Depths-1,000 meters = more alkaline/basic3,000 meters and deeper = more acidic again b/c the decay of sinking organic materials produces CO

2

Carbonate Compensation Depth

(CCD): The depth at which calcium carbonate dissolves as fast as it accumulates

Generally occurs around 4,500 meters

Water below the CCD is acidic enough to dissolve sinking shells (which are made of calcium carbonate)Slide56

Marine Science: Chemical OceanographyDay 4 – Biogeochemical Cycles

Objectives:How do the proportions of organic elements in seawater differ from the proportion salts?What is the biogeochemical cycle?

What elements is fundamental to all life?What are the roles of carbon in organisms?What are the roles of nitrogen in organisms?Why is phosphorous important to life?

What is the role of silicon in marine organisms?

What are the roles of iron and other trace metals in marine organisms?Slide57

Organic Dissolved Solids

Although the majority of dissolved solids are inorganic salts, there are many other types of organic solids that are also found in seawaterOrganic: Compound that contains carbon and is associated with living thingsThe Principle of Constant Proportions does not pertain to organic solidsConcentrations and proportions of organic material varies widelySlide58

Biogeochemical Cycle

All life depends on materials from the non-living (abiotic) part of the EarthOrganisms require specific elements and compounds to stay alive.Ex. Humans require oxygen gas, water, etcBiogeochemical Cycle: The continuous flow of elements and compounds between organisms and the earthSlide59

Fundamentals of Biogeochemical Cycles

All matter cycles...it is neither created nor destroyed...As the Earth is essentially a closed system with respect to matter, we can say that all matter on Earth cycles .Biogeochemical cycles are basically the movement (or cycling) of matter through a systemSlide60

The Cycling ElementsMacronutrients

: Required in relatively large amounts“BIG SIX": carbon , hydrogen , oxygen , nitrogen , phosphorous, sulfurOther Macronutrients: potassium , calcium , iron , magnesiumMicronutrients: Required in very small amounts, (but still necessary)boron (green plants)

copper (some enzymes)molybdenum (nitrogen-fixing bacteria)Slide61

Generalized Biogeochemical Cycle

Five cycles that we will focus on in Marine Science:The nitrogen cycleThe phosphorus cycleThe carbon/oxygen cycleThe water cycleThe silicon CycleThe circulation of chemicals in these biogeochemical cycles and interactions between cycles are critical for the maintenance of terrestrial, freshwater and marine ecosystems. Global climate change, temperature, precipitation and ecosystem stability are all dependent upon biogeochemical cyclesSlide62

Nitrogen Cycle

Organisms require nitrogen for organic compounds like proteins, DNA, and chlorophyll (the plant pigment used in photosynthesis)Nitrogen makes up 78% of the air and 48% of all dissolved gasses in seawater… gaseous nitrogen must be converted into a chemically usable form before living things can use itNitrogen Fixation: Bacteria in the soil can convert gaseous nitrogen into ammonium (lightning also fixes small amounts of nitrogen)

Nitrificaiton:

Nitrifying bacteria convert ammonium ions into nitrite and nitrate (some plants can use ammonium ions others need nitrates)

Ammonification

: Breaking down nitrogen compounds in the remains of organisms into ammonia – this is preformed by decomposers

Denitrification

: Conversion of ammonia, nitrite, or nitrates into N2 gas. Denitrifying bacteria take nitrogen compounds in the soil and convert them intro free nitrogen/N2 gasSlide63

earth.rice.edu

earth.rice.eduSlide64

NITROGEN CYCLESlide65

Woods Hole Interactive Nitrogen Cycle

http://www.whoi.edu/page.do?pid=83516 Slide66

Carbon and Oxygen Cycle

The main phases of the cycle are:Photosynthesis: During this process plants and algae take in carbon dioxide and release oxygen gas Cellular respiration: During this process organisms take in oxygen and release carbon dioxideDecay/Decomposition: When organisms die they are decomposed and any remaining carbon atoms are released into the atmosphere/ground

Fossil Fuels: Rich fuel composed of dead plant and animal matterCombustion: Burning of plant or animal matter, burning of fossil fuels, volcanic eruptions, etc. releases gasses into the atmosphere, ocean, and ground

Ocean Storage

: Large amounts of carbon are stored in the ocean in various forms Slide67

http://www.whoi.edu/main/topic/carbon-cycle slide of Carbon Cycle

http://www.whoi.edu/main/topic/carbon-cycle video of ocean rock in OmanSlide68

Carbon in the OceanSeas have plenty of carbon in many different forms:

Carbon dioxide in the atmosphere dissolves into the oceanCertain carbon containing rocks and minerals can be eroded and their sediments dissolve in ocean waterAnimals wastes and the decomposition of dead organisms and their wastes release carbon into the oceanBiological pump tends to concentrate carbon and other nutrients with depth – action by bacteria decomposing organic material. This pump transfers carbon from the atmosphere to the deep sea where it concentrates and remains for centuriesSlide69

Carbon and Oxygen Cycle- Human Impact

Humans are impacting the carbon cycle in various ways…Burning of fossil fuels- releases excessive amounts of CO2 that is causing global warming/global climate changeDeforestationPollution

britannica.comSlide70

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Oxygen Cycle

edhsgreensea.net

glogster.comSlide73

Water Cycle

Main Phases:Evaporation: Liquid water stored in lakes, rivers, streams, and oceans is heated and forms water vaporCondensation: Water Vapor in the atmosphere attaches to particles in the atmosphere like dust and condenses to form liquid water dropletsPrecipitation: Water in form of rain, snow, sleet, hail etc. fall from clouds

Groundwater: Precipitation infiltrates the soil/rocks and is stored in the groundRun-Off: Precipitation that is not absorbed into the ground flows into rivers, lakes, streams, and the ocean

Transpiration

: Water is taken up by the roots of plants and can be used to cool the plant as it evaporates from small holes in the leaves of plantsSlide74

Water Cycle Raphttp://www.youtube.com/watch?v=i3NeMVBcXXU

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Silicon Cycle

About three quarters of the primary production in coastal and nutrient replete areas of the world oceans is carried out by diatoms.Diatom: A phytoplankton that needs silicon (Si) for the build up of their opaline (silicate) shells. In low nutrient areas diatoms still contribute to about one third of the marine primary production.

Silicic acid is the biologically available form of silicon in the marine environment and its surface water concentration can severely limit diatom biomass build up.

The

silicious

tests (skeletons/shells) produced by diatoms tend to be much heavier than water and sink which provides for the transport of organic carbon (which is another element found in their shells) from the surface ocean into the deep ocean(the biological carbon pump).

Once in the deep ocean, their shells/skeletons form sediments like rocks and sand (silica is a major component of sand).MUCH later, these sediments are moved and may become exposed and eroded…

http://quercus.igpp.ucla.edu/research/projects/res_fr_main_silicon.htmSlide78

Silicon Cycle

nature.com

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Phosphorus Cycle

Phosphorus is important to marine life in a number of ways… it is component of ATP and ADP (energy for cells) and also a part of DNA (genetic information)Phosphorus is cycled through marine ecosystems in a number of ways:Plants obtain phosphorous from the soil or water in which they live

Animals obtain it by eating plantsWhen the animals die they decompose and the phosphorous is returned to the soil

When animals defecate (waste) phosphorus is also released. For example, bird guano is a primary source of phosphorus in seawater

Phosphorous is also washed into the sea from the weathering of rocks

Humans are disrupting this cycle…

Organic fertilizers and human pollution from detergents can release extra phosphorous into the environment and cause problems for fresh water and inshore marine ecosystems

Extra phosphorous can cause algae blooms – the algae will bloom out of control and when they die the bacteria that decompose them will use all of the oxygen in the water killing fish and other freshwater organismsSlide80

Phosphorus CycleSlide81

Chemical Factors Affect Marine Life’s Homeostasis

Homeostasis mechanisms protect an animal’s internal environment from harmful fluctuationsCellular Transport: living things must obtain materials from their environment and cellular transport is how living cells obtain materials/nutrients that they needThere are two types of cellular transport:Passive TransportActive TransportSlide82

Passive Transport

Passive Transport: Type of cellular transport that does not require energy because materials are being transported with the concentration gradient

Concentration Gradient: when materials are moved across a membrane from higher concentrations to lower concentrations3 Types of Passive Transport:Diffusion – movement of materials from high to low concentrations

Osmosis – diffusion of water across a semi-permeable membrane

Facilitated Diffusion – use of protein channels to move materials from high to low across a cell membraneSlide83
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Osmotic Solutions

Hypertonic Solution When the osmotic pressure of the solution outside the cells is higher than the osmotic pressure inside the cells, the solution is hypertonic. The water inside the cells exits the cells in an attempt to equalize the osmotic pressure, causing the cells to shrink Isotonic Solution When the osmotic pressure outside the cells is the same as the pressure inside the cells, the solution is isotonic with respect to the cytoplasm. This is the usual condition of red blood cells in plasma.

Hypotonic Solution When the solution outside of the cells has a lower osmotic pressure than the cytoplasm of the cells, the solution is hypotonic with respect to the cells. The cells take in water in an attempt to equalize the osmotic pressure, causing animal cells to swell and potentially burst. Plant cells swell and the cell wall pushes against the cell membrane creating

turgor

pressure. This is the usual condition of plant cells.Slide85

Osmotic SolutionsSlide86

Active Transport

Active Transport: Type of cellular transport that does require energy because materials are being transported against the concentration gradient (low to high)2 Types of Active Transport:Bulk Transport: Transporting large materials into or out of the cell membrane

Endocytosis: Taking material into the cellExocytosis: Taking material out of the cell

Membrane Pump: Using proteins in cell membranes to pump materials across the cell membrane Slide87

Osmoregulation in Different Environments

Each species has a range of environmental osmotic conditions in which it can function:Stenohaline – Organisms that tolerate a narrow range of salinities in external environmentEuryhaline – Organisms that tolerate a wide range of salinities in external environment:

short term changes: estuarine - 10 - 32 ‰, intertidal - 25 – 40‰long term changes:

Diadromous

fishes -spend part of life in salt water, part in freshwater

Catadromous

– live in freshwater and migrate seaward to spawn ex. eels

Anadromous

– born in freshwater, live in sea, migrate up river to spawn ex. salmon and sturgeon Slide88

OsmoregulatorsOsmoregulators

: Organisms that can adapt to changes in salinity of the surrounding seawaterOsmoregulators use active transport to maintain a stable internal salinity so this requires the use of energyHelps conserve loss of freshwater from their bodiesExamples include most vertebrate fish, sharks, etc. B/c they can adapt to changing salinities they survive in variations of salinities… Slide89

Osmoregulation: Sharks vs

Bony FishSHARKSMaintain internal salt concentrations lower than seawater by pumping salt out through rectal glands and through the kidneys, yet their osmolarity

is slightly hypertonic to seawater. Sharks retain urea as a dissolved solute in the body fluids.Sharks also produce and retain trimethylamine

oxide (TMAO), which protects their proteins from the

denaturation

by urea.

Retention of these organic solutes (urea, TMAO) in the body fluids actually makes the slightly hypertonic to seawater.

Do not drink water, but balance osmotic uptake of water by excreting urine.

MARINE BONY FISH

Marine bony fishes are hypotonic to seawater.

Compensate for osmotic water loss by drinking large amounts of seawater and pumping excess salt out with their gill epithelium.

Excrete only a small amount of urine.Slide90

Osmoregulation in Fish

quia.comSlide91

Osmoregulation in SharksSlide92

Osmoconformer

Osmoconformers: Organisms that cannot adapt to changing salinities. Internal salinities rises and falls with the waters surrounding themPassive transport occurs in these organisms so no energy is neededSome osmoconformers do well in changing salinities but most do NOT

Examples include many Hagfish and invertebrates like:MollusksJellyfishSquid

Octopus

dangerous-animals-pets.blogspot.com

phys.org