The science project put together by Science Buddies compares different areas in the ocean with regard to the speed in which plankton reproduce, to gauge the effects of different environmental conditions on the long-term growth of plankton as a species. Use such homemade items as a pair of pantyhose and an embroidery hook to make your plankton net and then put a bottle inside the netting to capture the plankton. You can capture several jars' worth of plankton at different locations in your community, from which you can compare the diversity of the varieties of organisms that you see, as well as the sheer number of different creatures. Use these figures to evaluate each site's overall healthiness for other ocean species.
Such species as the mussel, the crab, and many anemones, among others, are considered "intertidal" because they gravitate with the tides, living in the area between where the ocean comes at high tide and where it recedes to at low tide. However, this often means that they are left "high and dry" when the tide goes out. Because of this, it can be important to know tidal trends to assess how those trends will affect those ocean animals. An experiment on the Science Buddies site describes measuring the amount of time that a particular shoreline has water in the low tide zone, the middle tide zone, and the high tide zone. The high tide zone has the least coverage, with green algae as the sole vegetation. Crabs and barnacles will live here, as will sea stars and snails. The middle tide zone has constant wave motion and has more plant life. The low tide zone has the highest number of species.
Because of the extreme water pressures at the bottom of the ocean, gathering sediments from the sea floor is a highly expensive proposition, as scientists send equipment down to the floor to pick items up at different places, and use those samples to extrapolate what life is like at the sea's very bottom. To replicate this, fill a container with different types of substances, such as shells, stones or other objects. Make sure to include several different types of objects, and spread them out on the bottom. Give students one chance to stick their hand into the box, without looking, and pull up an item from the sea floor. They must put their hand on one object and bring it up. While one student might bring up a shell, another might bring up a yo-yo. Use this to lead into a discussion about the difficulty of making extrapolations using this sampling method, and about ways to ease that difficulty.
Richard Ellis, the renowned marine artist, has put together a book of drawings called "Deep Atlantic" that features creatures that live below the reaches of light from the surface. The drawings come from pictures of dead animals, and the PBS show "Nova" has assembled an interactive portrayal of these that appears under Juliant Rubin's collection of science experiments about the ocean. Students can view these pictures and speculate about the hazards and benefits of that environment for those creatures.