Environmental DNA (eDNA) is DNA that has been left behind by organisms in their environment in the form of skin cells, hair, mucus, faeces, urine, blood, saliva, gametes, and deceased remains. eDNA accumulates in water, sediment, soil and air, but persists for different times in these environments. eDNA can persist for hours to weeks in water compared to months to years in sediment. eDNA can be captured from environmental samples and used to survey single species or whole communities.