SummaryTenArtioposthia triangulatawere kept without food at 5°C, 10°C, 15°C, 20°C and 23°C. Survival and weights were recorded weekly. All planarians died within one week at 23°C and within three weeks at 20°C. One individual survived for 60 wk at 5°C. A negative exponential equation was fitted to average survival times for planarians kept at 5°C, 10°C, 15°C and 20°C. Negative exponential models could also describe the pattern of degrowth by planarians deprived of food. The results are discussed in relation to possible survival of the planarian outdoors in Northern Ireland and the implications for earthworm