OCNG 251 TAMU final test

Most fresh water fish are

hypertonic

hypertonic means

the fish's body cells contain more salt than the surrounding water.

Total number of catalogued species on Earth is:

1,800,000 and growing every year

how many species are discovered each year

2000

Estimate of total number of species on Earth is between

3-100 million (with a most likely range of 6-12 million)

How many species in the ocean?

228,000 marine species (13% total Earth species)

Why so few marine species?

- uniform conditions

-Less pressure to adapt

ex: Sharks same as 400 million yrs ago

because Temperature remains relatively stable and cold...

chemical reactions are slower.

75 % of land species are...

insects

out of 250,000 marine species, 98% are _____ and 2% are _______.

Benthic (98%) Pelagic (2%)

taxon richness

number of species.

The number of species (taxon richness) is not ______ across the ocean.

constant

Domains or "superkingdoms" group living organisms into three groups:

-Bacteria

-Archaea

-Eukarya

a simple, single-celled life form in which there is no membrane-bound nucleus, e.g. cyanobacteria.

Bacteria

simple single-celled organisms that look like bacteria. Often found in extreme environments.

Archaea

complex organisms with membrane-bound nuclei and other organelles in the cells (e.g. mitochondria, chloroplasts). Includes both single-celled and multicellular organisms; e.g. plants, animals, fungi, and protists.

Eukarya

7 taxonomy levels in order

• Kingdom

• Phylum

• Class

• Order

• Family

• Genus

• Species

How are Marine Organisms Classified?

according to where they live (their habitat) and how they move (their mobility)

Plankton (drifters / floaters):

- Includes all organisms (algae, animals, and bacteria) that drift with ocean currents

- Some capable of swimming, but it is weak and often only vertically

- Most of earth's biomass (the mass of living organisms) consists of plankton in the oceans!

Nekton (swimmers)

- All animals capable of moving independently of ocean currents by swimming or propulsion.

- Can determine own positions and some have long migrations.

Benthos (bottom dwellers)

organisms living on or in the ocean bottom

6 Types of plankton

Holoplankton

meroplankton

macroplankton

picoplankton

phytoplankton

zooplankton

Phytoplankton

Autotrophic - can photosynthesize and produce own food

Zooplankton

Heterotrophic - relies on food produced by others

Holoplankton

'Whole' lives as plankton

Meroplankton

- Part of lives as plankton

- Juvenile or larval stages

Macroplankton

Large floaters such as jellyfish or Sargassum

Picoplankton

Very small floaters such as bacterioplankton

How are Nekton Marine Organisms Classified?

• Independent swimmers

• Most adult fish and squid

• Marine mammals

- Whales, dolphins, seals

• Marine reptiles

- Sea turtles

3 types of benthos:

- Epifauna

- infauna

- Nektobenthos

live on the surface of the sea floor - attached to rock or moving on bottom (ex. Sea stars, anemones)

Epifauna

live buried in sediments (ex. Marine worms)

infauna

swim or crawl through water above the seafloor (ex. Crabs)

Nektobenthos

Benthos are most abundant in ____ water.

shallow

Many benthos live in perpetual...

darkness, coldness, and stillness.

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

- Temperature

- Salinity

- Turbidity

- Pressure

Phytoplankton need several basic things to survive:

1. Stay near the surface ocean for light

2. required nutrients

3. Expel water from their cells

what helps reduce sinking of small organisms

viscosity

Warm water =

- Lower viscosity

- Lower density

- More appendages to stay afloat

Cold water =

- Higher viscosity

- Higher density

- Fewer appendages needed

Viscosity makes it difficult to swim, so marine organisms use:

streamlining

Viscosity is a _____ for small organisms and a _______ for larger organisms

- plus

- liability

small marine organisms grow _____ _____ to increase surface area, especially in _____ _____.

Unusual appendages

warm areas

Oil in micro-organisms will...

increase buoyancy

Organisms withstand small variation in temperature

Stenothermal

Organisms withstand large variation in temperature

Eurythermal

Organisms withstand only small variation in salinity

Stenohaline

Organisms withstand large variation in salinity

Euryhaline

what was Small and overlooked until relatively recently?

Photosynthetic Bacteria

Synechococcus may be found in Abundance up to:

100,000 per ml.

The very small Prochlorococcus may form ____ of the ocean's photosynthetic biomass, making it the most abundant photosynthetic organism on Earth.

half

Especially important for phytoplankton

•Need to be near surface for light for photosynthesis

Buoyancy

Rate of settling can be decreased by increasing drag/frictional resistance due to:

size

Living cells have water permeable walls, which means:

•Water can easily pass

•Dissolved salts cannot

Water molecules pass from LOW salinity to HIGH salinity

Osmosis

An organism has the same salinity fluids as ocean water, which means it is:

•Isotonic

•No movement of water

An organism has higher salinity fluids than ocean water, which means it is:

•Hypertonic (saltier)

•Water moves into cells

Organism has lower salinity fluids than ocean water, which means it is:

•Hypotonic (less salty)

•Water moves out of cells

how are dissolved gasses an adaptation to marine life?

Animals extract dissolved oxygen (O2) from seawater through gills

If dissolved oxygen gets too low then the organisms will...

suffocate

Some marine organisms are nearly _______ to avoid predation

transparent

what are three ways marine life blends into its surroundings?

•Camouflage through color patterns

•Countershading

•Disruptive coloring

Daily _______ Migrations of the _______ ________ Layer, which often contains copepods krill, types of fish

vertical

Deep Scattering

the deep scattering layer is also known as:

"false bottom" on SONAR

the Deep Scattering Layer (DSL) is how deep during night? day?

100-200m (night)

up to 900m (day)

Increases about 1 atmosphere (1 kg/cm2) with every...

10 m (33 ft) deeper

why do Many marine organisms not have inner air pockets

so they don't feel pressure changes

(some marine mammals have a collapsable rib cage)

means to be in the water, surrounded by water at any depth

Pelagic (open ocean)

continental shelf

neritic

means to be on the bottom or on a solid surface

Benthic (sea floor)

Pelagic Waters: Characterized by Depth:

•Epipelagic (0-200m)

•Mesopelagic (200-1000m)

•Bathypelagic (1000-4000m)

•Abyssopelagic (>4000m)

Pelagic Waters: Characterized by Light:

•Euphotic (0-100m)-enough light for photosynthesis

•Disphotic (100-1000m) -small but measurable light

•Aphotic (>1000m) - no light

is the rate at which energy is stored by organisms through the formation of organic matter (carbon compounds).

Primary productivity

primary production energy comes from solar radiation (_________) or chemical reactions (__________).

photosynthesis

chemosynthesis

99.9% of the ocean's biomass relies directly or indirectly on ________ for food.

photosynthesis

Biomass is the

mass of living things

Total amount of organic carbon produced by photosynthesis per unit time in certain area

Gross primary production

chemical reaction that releases energy from organic molecules when metabolized by oxygen

Respiration

Respiration completed by both:

- Autotrophs (to provide them energy for their cellular machinery)

- Heterotrophs that eat autotrophs!

what supports the entire ecosystem?

net primary production

How do we measure primary productivity?

How do we measure primary productivity

- Most direct method is plankton nets

- Chlorophyll measurement

-Satellites (SeaWiFS)

-Now use MODIS

Two main factors determine the amount of primary production in a given ocean region:

1. Availability of solar radiation

2. Availability of nutrients

<1% of light reaches below

100 m depth

Photosynthesis only occurs in the ______ _____, which extends from the surface to the compensation depth for photosynthesis

euphotic zone

the depth where there is enough light for photosynthesis to equal respiration (zero net primary production)

Compensation depth for photosynthesis

The compensation depth for photosynthesis is approximately _____ m in the open ocean and may be less than _______ m in the coastal zone where the waters are more turbid.

100 m

20 m

Ocean selectively absorbs visible light of the _______ _____________ (red, orange and yellow)

longer wavelengths

life in the oceans depends on the availability of nutrients such as...

nitrate

phosphate

silicate

iron

is there more nutrients further or closer to the coast?

closer

does warmer or colder water have more biomass?

colder

where does most nutrients come from?

river runoff

What limits primary production in tropical oceans?

Solar radiation is high, but nutrients are low

What limits primary production in temperate oceans?

it depends on the season

Highest overall primary production (annually) happens in

temperate regions

Polar regions have highest ________ _______ but they are short-lived and seasonal.

phytoplankton "blooms"

Protista includes the

red algae

- Most abundant and widespread of the seaweeds

- Over 4000 species

- Many attached to bottom

red algae*

Plantae includes the

brown algae

- Classic "seaweed"

- Yellowish/brown in color

- Washes up on beaches

brown algae*