The Origins Of Life
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The Origins Of Life

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From the marine science perspective: a description of how life began, evolution, oxygen and evolution, ocean zones and marine lifestyles.

From the marine science perspective: a description of how life began, evolution, oxygen and evolution, ocean zones and marine lifestyles.

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  • 1. The Origins of Life
    • The oldest fossils came from the ocean shallows
      • Cyanobacteria: aquatic, photosynthetic
      • 3.5 billion years old
    • Scientists don’t know how life began
      • Many hypotheses proposed
  • 2. Abiogenesis
    • Scientists propose that simple molecules randomly combined and separated.
    • Larger, more complex molecules fromed
    • When these were able to reproduce, life was formed
  • 3. Oxygen and Evolution
    • First organisms were simple heterotrophs
      • Rely on consuming compounds to obtain energy
    • Autotrophs appeared (3-3.5 bil yrs)
      • Can create organic chemical energy from inorganic compounds
      • Increased atmospheric O2 from 1-21% by breaking C0 2  0 2
  • 4. Oxygen
    • O 2 important
      • because reactions using 02 allow organisms to use chemical energy more efficiently
    • Biologists theorize that O 2 allowed the development of mitochondria
      • Cellular organelles that use O 2 to process energy
  • 5. Theory of Evolution
    • Many views on how life started
    • This is a broadly accepted theory in the scientific community
    • Natural Selection
      • Organisms with characteristics that favor survival pass those characteristics to offspring
      • Originally proposed by Charles Darwin
  • 6.
    • Over millions of years natural selection resulted in the variety of life we see today
    • Most scientists believe that changes came about in spurts due to environmental changes
    • Existing organisms adapt and become new species as they fill niches left by extinct species
  • 7. Scientists theorize…
    • Single celled organisms evolved from independent existence to life in colonies
      • Which then evolved into multicellular organisms
      • Lived
  • 8. Ocean Zones
    • Water portion
    • pelagic
      • Neritic: between low tide & edge of continental shelf
    • Oceanic
      • Epipelagic: sunlight penetrates, life
      • Mesopelagic: some light, not much life
      • Bathypelagic: deep
      • Abyssalpelagic: deeper
      • Hadalpalagic: deepest (Hades= hell)
  • 9.
    • The Sea floor
    • Benthic zone
      • Littoral: intertidal
      • Shelf: low tide – cont. shelf
      • Bathyal: deep
      • Abyssal: deeper
      • Hadal: deepest
  • 10. Marine Lifestyles
    • Marine scientists classify life into 3 lifestyles:
      • Plankton, nekton, benthos
    • Plankton: drift with ocean currents, can be zooplankton, phytoplankton
      • Neuston are the plankton that float at the surface. Ex.?
  • 11.
    • Nekton: swimmers
      • Examples?
      • Most are vertebrates
      • Most of the predators are nekton
  • 12.
    • Benthos: live on or in the bottom, can move about or be sessile.
      • Epifauna: animals that live on the sea floor
      • Epiflora: plants that live on the sea floor
      • Infauna: live partially or fully buried in sea floor