The Seafloor The ocean floor is not flat. It has all the features and landforms that are found on dry land.

**Copy the diagram of the seafloor from the board.** The continental shelf and slope are the edge of the continent.

Rift zone - where ocean floor is spreading; hot lava oozes out through cracks; solidifies and becomes new land Mid-ocean ridges - mountain chains alongside rift zones; many volcanoes Trenches - formed when one piece of the seafloor is pushed beneath another; forms a deep canyon Ex. Marianas Trench = 11 km deep, Grand Canyon = 1.6 km Island - top of underwater mountain that reaches the surface Abyssal plain - flat area Seamount - underwater mountain

Waves cause the shoreline to constantly change. Sandy beaches are eroded more rapidly than rocky shores.

Life in the Ocean Living in the ocean can actually be easier than living on land. 1.) Organisms in the ocean use less energy for movement due to buoyancy. 2.) Temperature changes are less drastic than on land. 3.) There is never a lack of water. 4.) Waste disposal is easy and cleaner. 5.) External fertilization is carried out very easily.

Many ocean plants carry out photosynthesis, but other organisms carry out chemosynthesis. This means they use chemicals other than oxygen to make their own food. For example, bacteria near deep sea vents use sulfur to make their energy.

Ocean organisms fall into one of three main categories based on their movement. Plankton - mostly microscopic; “drifters”; can’t move on their own, so they are carried by the currents; at top of ocean Ex. - diatoms; algae; krill

Nekton - larger animals; able to swim; can move to all different levels Ex. Fish, whales

Benthos - bottom dwellers; do not leave the bottom; usually poor swimmers; may even live attached to the bottom Ex. Sea anemones, starfish, crabs, clams