Coping Pods

The four major species of copepods in the Beaufort Sea all have different sizes, different life cycles, and different prey. L to R: Metridia longa (~2.5 millimeters), Calanus glacialis (~4mm), Calanus hyperboreus (~7mm). The smallest, Oithona similis (0.5mm) is below the center. The largest species, Calanus hyperboreus, is a critical link in the Arctic food web, eating phytoplankton and microzooplankton when the returning spring light triggers their growth. They are eaten in turn by many larger animals. (Photo by Carin Ashjian, Woods Hole Oceanographic Institution)