Sunfish are characterized by basking behavior, where they regularly come to the surface to regulate their body temperature in the warmer waters near the surface, a behavior that inspired their common name. Studies from Nagasaki University and Kagoshima Japanagoshima City Aquarium show that molids use these surface periods to regulate their body temperature after diving into deeper and cooler waters. Dives up to several hundred meters can expose them to colder temperatures, and ocean sunfish combat  heat loss by adjusting their blood flow and movement patterns. By returning to warmer surface waters, they can quickly warm their muscles and maintain the activity needed for feeding and swimming.

This flexibility allows ocean sunfish to survive in a range of water temperatures and increase diving depth. Scientists in this study documented that they can dive as deep as 1,600 feet (500 m) before resurfacing to bask and warm up. During these deep dives, sunfish are likely searching for prey that tend to live in cooler waters.

The research suggests that Mola mola have an ability to control how quickly they lose or gain heat depending on their behavior and environment. When they dive into cold and deep waters, they seem to slow down heat loss. When they return to the warmer surface, they increase heat exchange to warm up more quickly. Their thermoregulatory behavior is rare among large bony fish, which shows that ocean sunfish have evolved some unique adaptations to thrive across a variety of thermal environments.