A rare form of the widely distributed Western Brook lamprey, the Morrison Creek lamprey lives exclusively in the Morrison Creek watershed on Vancouver Island, British Columbia. Morrison Creek is a small, freshwater stream flowing into the Puntledge River at Puntledge Park, Courtenay, British Columbia. The specific habitat required to support the Morrison Creek lamprey is not known. However, Morrison Creek is a cool, clean, year-round stream with relatively constant temperature and flow rate.

The most unique and interesting characteristic of the Morrison Creek lamprey is that it produces two different life forms from a single population-those with teeth (parasitic) and those without (non-parasitic). Morrison Creek Lampreys range in size from 10 to 15 centimetres in length. The parasitic form can be distinguished from the non-parasitic form by its silver upper body, white lower body and prominent teeth. Parasitic Morrison Creek lampreys live for several months longer than non-parasitic lampreys, which mature, spawn and then die.