500
This is a sentence from the text that shows what is happening in the illustration on pg.10:
a. Amchitka and Shemya Islands are surrounded by rocky ocean floor and clear water of the same temperature.
b. All the plants, animals, and other living things in one place interact with one another in many ways.
c. The scientists discovered that the sea otters triggered a series of ecosystem changes.
What is b. All the plants, animals, and other living things in one place interact with one another in many ways?