Oceans a very large expanse of water 71% of the Earth's surface is covered by the oceans 97% of Earth's water is in the oceans 80% of life on Earth is found in the ocean

Estuary a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea Most ocean life starts out in the estuaries ("sea's nursey")

Brackish water Water that is a mix of salt and fresh water This is the water found in estuaries. Organisms in this water must be able to adapt to extreme conditions.

Marine ecosystem Aquatic ecosystems in saltwater Ex: salt marshes, intertidal zones (beaches), estuaries, lagoons, mangrove forest, coral reefs, the deep sea, and the sea floor

biodiversity the variety of life in the world or in a particular habitat or ecosystem.

upwelling a process in which deep, cold water rises toward the surface bringing nutrients from the bottom Upwelling attracts many lifeforms to the surface of the ocean Upwelling is caused by wind and ocean currents

ocean currents a continuous, directed movement of seawater generated by forces acting upon it

photosynthesis a process used by plants and other organisms to convert light energy, normally from the Sun, into chemical energy How plants make their own food

chemosynthesis A process used by some organisms to convert chemical energy into food Many sea floor organisms use this method to make their food. Different from photosynthesis because the organisms use chemicals instead of sunlight

Hydrothermal vent a fissure/crack in the ocean's floor from which geothermally heated water is released Many worms and bacteria live near these vents and use chemicals from the vents to make their food through chemosynthesis

salinity the measure of all the salts dissolved in water 1 kg of ocean water = 35 g of salt All marine ecosystems have a high salinity

plankton a diverse group of organisms that live in the ocean and that cannot swim against a current. Main source of food for many ocean animals Bottom of marine food web 2 kinds: phytoplankton (like plant) and zooplankton (like animals)