Why does it matter if a species go extinct?
When a species go extinct, with it the whole food web get disturbed due to inter-relationship and interaction between organisms. The species of organisms which might have been dependent on the extinct species for food may also get extinct due to starvation until it get an alternate option. If the dependent species shift its choice of food on another species then there might be a competition for food with other species. Thus, in a nutshell, a extinct species affect the whole ecosystem.
