Dolphin This term has often been misused in the US, mainly in the fishing industry, where all small cetaceans (dolphins and porpoises) are considered porpoises, while the fish "dorado" is called dolphin fish. In common usage the term 'whale' is used only for the larger cetacean species, while the smaller ones with a beaked or longer nose are considered 'dolphins'. The name 'dolphin' is used casually as a synonym for bottlenose dolphin, the most common and familiar species of dolphin. There are six species of dolphins commonly thought of as whales, collectively known as blackfish: the killer whale, the melon-headed whale,
Common species because common species shape ecosystems, contribute disproportionately to ecosystem functioning, and can show rapid population declines, conservation should look more closely at how the trade-off between species extinctions and the depletion of populations. Common species Common species and uncommon species are designations used in ecology to describe the population status of a species. Commonness is closely related to abundance. Abundance refers to the frequency with which a species is found in controlled samples; in contrast, species are defined as common or uncommon based on their overall presence in the environment. A species may be locally abundant without being common. However,