The ocean.

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The ocean.

• Divided into regions by depth
• Epipelgic (photic zone) to 200 meters (650 ft)
• Mesopelagic to 1,000 meters, some dim light.
• Below Mesopelagic is the deep sea.
• Bathypelagic goes to 4,000 meters.
• Abyssopelagic goes to 6,000 meters.
• Hadapelagic goes beyond 6,000 meters.

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Main Thermocline

• The layer between 200 and 1,000 meters where the
  temperature drops rapidly as depth increases.
  This is a transition zone between the warm
  surface layers and the cold deep water.
• The circulation of the water permits food and
  oxygen to be provided to organisms below the
  photic zone into deep water.

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Organisms of the Epipelagic

• Net Planktons those large enough to be caught in
  nets micro, meso, macro, and megaplanktons.
• Nanoplankton (picoplankton) are too small to be
  trapped in nets bacterioplankton.
• Organisms are further divided into Phytoplankton
  (photosynthesis performing) and Zooplankton
  (heterotrophic, herbivores which also eat other
  zooplankton)

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Neuston

• These are organisms that live on the surface.
• Usually have a structure which is inflated and
  keeps them afloat as in the Portuguese Man of War
  and Brown Algae.
• The water strider (Hallobates) is the only insect
  that lives in open seas that does not have a gas
  filled float, it must stride or drown.

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Staying in the epipelagic zone.

• To stay in the same depth, organisms must either
• increase resistance
• or
• increase bouyancy

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• To increase resistance, organisms
• 1. May be very small to have a better surface
  area to volume relationship which creates drag.
• 2. May take on a flat or umbrella like shape
  to create drag.
• 3. May have protruding spines or projections
  to increase drag to prevent sinking.

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• To Increase buoyancy
• 1. Organisms can store lipids, sucha s fats
  or oils in the body making them less dense.
• 2. Pockets of gas in the form of bladders or
  floats provide bouyancy. Because of changes in
  pressure, the organism must be able to adjust the
  gas volume to remain bouynat.

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Zooplankton

• First link in the flow of food in the food chain
  within the epipelagic zone.
• Consists of
• Protozoans ( most important being the flagellates
  which feed on the microscopic pico- and
  nanoplankton.)
• Copepods ( dominate the net plankton species,make
  up 70 of the community.)

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• 3. Crustaceans (Krill which dominate the polar
  seas,and decapods like crabs, shrimps,and their
  relatives may be dominant in certain areas at
  certain times.)
• 4. Non-crustacean zooplankton ( includes the
  relatives of the sea squirts or tunicates called
  salps that live on the bottom. Larvaceans which
  live in mucous like houses they create, filter
  feed and are also important to linking the
  microscopic organisms to those higher in the food
  chain.)

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• Pteropods ( small snails with modified foot that
  forms a pair of wings to keep it afloat. Catch
  food with mucous nets.)
• Chaetognaths ( arrow worms, feed on abundant
  copepods as well as diverse other organisms.)
• Siphonophores (drifting colony of cnidarians with
  members specialized to perform certain tasks.)

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• Ctenophores ( comb jellies which resemble
  jellyfish except that they have eight rows of
  cilia.)
• Meroplankton (Temporary members of the
  zooplankton include the larvae of various species
  living in the water column.)

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Nekton the strong swimmers.

• Included in this group are
• Fishes
• Marine mammals
• Squids
• Turtles
• Sea snakes
• Penquins

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Largest Nekton

• Krill eating whales, whale shark, and the basking
  shark.

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Nekton top trophic levels.

• Some feed on plankton.
• Most feed on other smaller nekton.
• Sperm whales feed on giant squid 33 feet long.
• Killer whales are top predators feeding on
  porpoises and seals.
• Large sharks eat seals, billfishes, and
  sailfishes as well as other sharks.

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Predators and their prey.

• Sense organs
• Coloration and camouflage
• Swimming
• Vertical migration
• Behaviors