As an ectotherm living in a just-above-freezing environment, the Greenland shark has the lowest swim speed and tail-beat frequency for its size across all fish species, which most likely correlates with its very slow metabolism and extreme longevity. It swims at , with its fastest cruising speed only reaching . Because this top speed is only half that of a typical seal in their diet, biologists are uncertain how the sharks are able to prey on the faster seals. It is hypothesized that they may ambush them while they sleep.