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Adaptations of Marine OrganismsThe marine

environment is more stable than land.

Organisms in the ocean are less able to withstand environmental changes.

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Adaptations of Marine OrganismsPhysical support

BuoyancyHow to resist

sinkingDifferent support

structures in cold (fewer) rather than warm (more appendages) seawater

Smaller size

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Adaptations of Marine OrganismsHigh surface area

to volume ratioUnusual

appendages to increase surface area

Oil in micro-organisms to increase buoyancy

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Viscosity and Streamlining AdaptationsStreamlining

important for larger organisms

Less resistance to fluid flow

Flattened bodyTapering back end

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Temperature and Marine LifeNarrow range of temperature in oceansSmaller variations (daily, seasonally,

annually)Deep ocean is nearly isothermal

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Ocean TemperatureMore stable than land for four reasons:

Higher heat capacity of waterOcean warming reduced by evaporationSolar radiation penetrates deeply into ocean

layersOcean mixing

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Cold vs. Warm Water SpeciesSmaller in cooler seawaterMore appendages in warmer seawaterTropical organisms grow faster, live shorter,

reproduce more oftenMore species in warmer seawaterMore biomass in cooler seawater (upwelling)

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Temperature and Marine OrganismsStenothermal

Organisms withstand small variation in temperature

Typically live in open oceanEurythermal

Organisms withstand large variation in temperature

Typically live in coastal waters

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Salinity and Marine OrganismsStenohaline

Organisms withstand only small variation in salinity

Typically live in open oceanEuryhaline

Organisms withstand large variation in salinityTypically live in coastal waters, e.g., estuaries

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Marine vs. Freshwater Fish