Research Product

The sheepshead minnow may be the most eurythermic of all known fishes. This species' physiological (static or plunge) and ecological (dynamic) thermal tolerance polygons have areas of 1380 C2 and 1470 C2, respectively, which are among the largest ever measured for a fish. In addition, sheepshead minnows are more resistant to both high and low lethal temperatures than are other fish species. Sheepshead minnows acclimated to 5 and 30 C have CTMin-CTMax of 0.6-34.6 C and 11.3-44.2 C, respectively. The CTMax increased to 45.1 C for fish exposed to a thermoperiod of 37-42 C for 30 days. At temperatures below 10 C, fish burrow into the substrate, presumably to maintain body temperatures above the lower physiological limit of -1.8 C. Physiological and behavioral adaptations allow sheepshead minnows to survive in extreme tidal pool habitats where temperatures can range from -1.9-43 C.