Ecological space is relevant to ethics not in virtue of being an evaluative term or referring directly to any determinate object of evaluation. It is primarily a descriptive term. What is shown here, though, is how what use of the concept allows us to capture something morally important about the way humans’ moral relations with one another are mediated through multifarious natural relations. Ethical implications of the concept of ecological space can be drawn out from the focus it brings to issues arising from the finitude and vulnerability of habitats. In this planet’s biosphere, there has always been competition of various kinds – within, among, and between species, populations and communities of organisms – for adequate environmental resources. The complexity of life also means that many organisms are themselves environmental resources for others. These natural ecological processes in themselves are hardly appropriate, or even possible, matters for ethical regulation by humans. Ethical questions do arise, however, when consciously directed activities of human beings cause harm to the environments or resources that other human beings depend on.