Figure 14.32: Sea turtles are found all over the oceans, but their numbers are diminishing.
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weasels (Figure14.34). The final type of ocean marine mammal is the polar bear, which
depends heavily on the ocean for survival and is adapted to a life around the sea.
Interactions Among Ocean Organisms
To best understand how ocean organisms interact, it is necessary to consider the particular
environments in which they live. There are four main ocean habitats: the intertidal zone
and shore, reefs, the open ocean, and the deep sea including trenches. Most organisms have
some adaptations specific to their preferred habitat.
A great abundance of life can be found in the intertidal zone. Many intertidal animals can
live in or out of the water; some spend one part of their lives in the water and another out
of the water. They must be adapted to frequent shifting of water levels and wave impacts.
In response, many have hard shells and strong attachments that keep them safe. Some
animals, like marine mussels, cling steadily to a rock for their entire lives (Figure14.35).
Many young organisms get their start in estuaries, which are special ecosystems affected by
the tides, where freshwater and salt water come together.
Reefsare built up by corals and other animals that deposit the mineral calcium carbonate to
make rock formations near the shore. They support a complex ecosystem of ocean organisms
that live within the coral reef. These diverse organisms have complex interactions with one
another; some species help each other to survive. When reefs are destroyed or polluted,
certain species can be affected more than others. Harm to one species may have adomino