Green sea turtles that eat jellyfish show surprisingly good nutrition: Comparative research by the University of Tokyo

Green sea turtles swim leisurely, mainly eating seaweed and seagrass, but in some regions, they also eat jellyfish. A research group from the University of Tokyo and others used a method of attaching small data loggers to the animals to study subadults (individuals not yet fully mature) from the herbivorous Yaeyama Islands (Okinawa) and from the Sanriku coast (Iwate), where they also eat jellyfish, approaching the mysteries of their dietary habits.

The results showed that turtles in Sanriku were active for longer periods and fed less frequently yet were in better nutritional condition. This is truly surprising given that jellyfish are mostly water and appear to have low nutritional value. Professor Katsufumi Sato, who studies behavioral ecology, said, "In winter they stay near the Izu Islands, and in summer they deliberately migrate north to Sanriku. Jellyfish must be an attractive food source. I was surprised. Sea turtles at tropical and subtropical nesting sites are often studied, but the majority of time outside the breeding season should represent their true nature."

The research group consists of the University of Tokyo, the NPO Sea Turtle Association of Japan, and Meijo University. The results were published in the international marine biology journal Marine Biology on July 23, and announced by the Atmosphere and Ocean Research Institute, the University of Tokyo, on August 4.