OCN 201 Biology Lecture 3Professor Grieg Steward

Classification of Marine Life & Habitats

C

H

H

H

S

carbon dioxide

sugars

nucleotides

lipidsamino acids

Autotrophs can make the organic building blocks of life starting from carbon dioxde

Heterotrophs have to eat organics

• Autotrophs - use CO2 to make organics

• Who: All plants, some protista and bacteria

• Can use sunlight (photo-) or chemical (chemo-) energy

• Heterotrophs - Need to consume organic compounds• Who: everything that is not autotrophic

• Mixotrophs - They can do both!

Classifying Marine Organisms by Nutrition

Autotrophic Cell

CO2 H2O+

Sugar

O2+

Energy

C6H12O66 6 6

Cells are more than sugar. Other compounds are built from simple sugars plus nutrients (Nitrogen, Phosphorous) & trace metals)

Autotrophy(photosynthesis or chemosynthesis)

Autotrophic Cell

CO2 H2O+ O2+C6H12O66 6 6

RespirationReversing the reaction yields energy the cell can use

Energy

Heterotroph

CO2 H2O+ O2+C6H12O66 6 6

HeterotrophyHeterotrophs consume organics. Much is respired to get energy and some is used as building

blocks to grow.

Energy & growth

Mixotrophy

Very common among marine planktonMany Protists in the ocean are both

phytoplankton AND predators!

Photosynthesis &predation

Mixotrophs can do this

Carbon Dioxide

Sugar

Water

But when nutrients are scarce

So they EAT other cells to get their nutrients

They can’t make all the necessary building blocks

especially nitrogen (N) and phosphorus (P)

> 3.5 billion

700 million

500 million

2 billion

Photosynthesis (Cyanobacteria) Photoautotrophs Chemoautotrophs

Heterotrophs Mixotrophs

Heterotrophs

ANIMALSFUNGI

Photoautotrophs

PLANTS

Multicellular Life

Eukaryotes (Protists)

Photoautotrophs Heterotrophs

Mixotrophs

Bacteria and Archaea

Venus Fly TrapSea Slug

Eastern Emerald Elysia

“Mixotrophic” Animals Truly Mixotrophic Plants

Upside-down Jelly Cassiopea

Photo: Patrick J. Krug

Photo: Linda & Jason

Pitcher PlantLaurence Gaume, Yoel Forterre

thisiswhyimbroke.com

EXCEPTIONS

• Benthic (benthos = bottom)

• Pelagic (pelagius = of the sea)

Classifying Marine Organisms by Habitat

Ocean Habitats

PELAGICBENTHIC

Intertidal (littoral)

zone

• Benthic (benthos = bottom)• Infauna• Epifauna

• Pelagic (pelagius = of the sea)• Plankton (Drifters, weak swimmers)

• Nekton (Swimmers)

Classifying Marine Organisms by Lifestyle

Infauna

Epifauna

35 mm

5 mm

PelagicOrganisms

Nekton(all are animals)

Planktonphytoplanktonzooplanktonbacterioplankton

Physical Divisions of the Marine Environment

4000 m

Bathyal

Abyssal

6000 mHadal

Littoral (intertidal)

200 mSublittoral

Supralittoral (splash zone)

NERITIC OCEANIC

EpipelagicMesopelagic

Bathypelagic

Abyssopelagic

Hadalpelagic

1000 m

• Temperature & Light DECREASE with Depth & Latitude

• Pressure INCREASES with Depth

• Salinity more variable near shore

• Air exposure in the littoral zone

Physical & Chemical Factors Affecting Life

Pressure Increases with Depth

Photo courtesy Kate Achilles

Deep-diving marine mammals have collapsible lungs

Temperature VariationsTemperature Decreases with Depth

POLAR

POLAR

TROPICAL

TEMPERATE

TEMPERATE

Temperature Decreases with Latitude

Light Variations

SunlightPressure

Light energy

Light intensity decreases with latitude and with depth

Pressure

TOTAL light and COLOR Spectrum Vary with depth

UVRed BlueYellow Green

about 600 m

20 to 100 m20 to 100 m“Good” Light

about 600 m

Twilight

No Light

Euphotic zone= where photosynthesis is possible!

Disphotic zone= there is light but not enough for photosynthesis!

No light from the sun penetrates

Euphotic

Disphotic

Aphotic

Photosynthesis Feeds The Ocean

Energy

Food

The Pelagic Divisions (By Light)

about 600 m

TwilightDISPHOTIC ZONE

20 to 100 m“Good” LightEUPHOTIC ZONE

APHOTIC ZONE No Light

Photosynthesis can only happen up here!