a type of hot spring seen on land that episodically erupts jets of hot water and steam. It results from ground water being heated by coming in contact with hot rock deep in the Earth's crust, and then rising to the surface.

algae (a simple type of plant that can photosynthesize) that live together with another organism in a mutually beneficial relationship.

small or microscopic animals that float or drift in great numbers in fresh or salt water near the surface and are the base of the ocean food chain.

used to describe 1) an organism that can live only with free oxygen, or 2) an environment containing free oxygen.

used to describe 1) an organism that can live without free oxygen, or 2) an environment that contains no free oxygen.

completely lacking free oxygen (O2

micro-organisms that belong to a major division of life, as different from bacteria as humans are.

the layer in the Earth below the lithosphere that is weak, probably due to the presence of some molten material. It is this weak layer that allows the tectonic plates to move.

relating to or coming from the south, especially the southern hemisphere

 C