1. Cenozoic Oceans
Early Cenozoic animals include massive creatures like the Megalodon Shark.
Whales and marine mammals diversify in this era.
All modern organisms in todays oceans are present.
Late Eocene extinction about 35 million years ago caused about 15% of oceanic organisms to go extinct.
Is another extinction coming soon?

3. Life Zones of the Ocean Defined by homogeneous physical features
Divided on basis of light, temperature, salinity, depth, latitude, and water density.
However, easiest to classify by light and location.
Light: Aphotic (no light) and Photic (light) Zones
Light governs photosynthesis and primary productivity
Location: Division between water and ocean bottom.
Pelagic Zone: Open water
Benthic Zone: Ocean bottom

4. Ocean Life Zones

5. Pelagic Zone Divided into 2 subsections:
Neritic Zone: Shallow water, near shore over the continental shelf.
Oceanic Zone: Deep water beyond the continental shelf.
Oceanic Zone further subdivided by depth:
Epipelagic zone: Shallow, Photic zone
Mesopelagic: Middle zone, aphotic.
Bathypelagic: Depth zone, aphotic
Abyssopelagic: Means without bottom. Deep trenches.

6. Benthic Zones Benthos or Benthic means bottom.
Benthic zone is subdivided as well.
Littoral Zone: of the shore. Intertidal region of coast.
Sublittoral Zone: Subtidal region. Ocean floor of continental shelf.
Bathyal Zone: Seabed from the continental slope to abyssal plain.
Abyssal Zone: Seabed of abyssal plain.
Hadal Zone: Hades means underworld. Seabed of trenches.

7. Life in Pelagic Zones
Plankton: the mass of mostly microscopic organisms that float or drift freely in the waters of aquatic (freshwater and marine) environments. (Algae and phytoplankton, jellyfish).
The basis of all life in the ocean.
Make oxygen for us to breath.
Nekton: all organisms that swim actively in open water, independent of currents. (Fish, sharks, whales, squids, octopus, etc.).

8. Life in Benthic Zones
Benthos: organisms that live at the bottom of oceans or bodies of fresh water. (Sea urchins, Sea stars, sea cucumbers, sand dollars, crabs, lobsters, shrimp, most bivalves).
Intertidal and Sublittoral Zone: zones where most life is found. Why?
Bathyl Zone: Not much life can survive here but squid, octopus, and whales can flourish.
Both abyssal and hadal zones have very few life forms but some life does exist.

9. Permian Ocean
Largest mass extinction ever took place at the end of the Permian.
Permian-Triassic or P-T Extinction.
Over 90% of all organisms in the ocean went extinct! 70% of all land organisms extinct.
Trilobites are extinct at end of Permian.

10. Mesozoic Oceans Triassic, Jurassic, Cretaceous periods.
Reptiles and dinosaurs diversified on land.
Large marine reptiles dominated oceans.
Plesiosaurs, Ichthyosaurs diversified.
Sea stars, sea urchins, sharks, an rays also flourished in Cretaceous.
K-T mass extinction wipes out dinosaurs on land and marine reptiles in the oceans.