This document discusses ecosystems, habitats, food chains, and the relationships between different organisms within an environment. It provides examples of how different animals such as seals, squirrels, and fish are adapted to their environments. It also explains producers and consumers within food chains, with plants being producers, herbivores being primary consumers, carnivores being secondary consumers, and omnivores consuming both plants and animals. Predator-prey relationships and complex food webs are described. The document closes by discussing endangered species and reasons why animals become threatened or extinct.