Please read the pages indicated by Z-26 and study Behavioral Objective #38. The atmosphere is not truly a habitat for any organism. Birds and insects fly in it, seeds, spores, and small organisms are born aloft for a time, but all of these are actually terrestrial organisms. The terrestrial habitat is a thin layer, or stratum, covering the planet only to a thickness of 60 meters at the most.

The ocean, on the other hand, constitutes about 78% of the earth's surface. It is a layer of 4000 meters average thickness, and offers for living nearly 300 times the space that land does. This vast environment has profound effects on atmospheric conditions. Conversely, the atmospheric conditions that regulate climate on land greatly influence conditions in the ocean. The oceans are divided into the following catagories: photic/ benthic, intertidal/near-shore. Organisms living in the oceans may be classified as pelagic and abyssal life forms.  In your notes write definitions and list examples for these terms.

Organisms that are free-swimming or floating their entire lives are called ________.

Most life in the open ocean is limited to the ________.