GALAPAGOS ISLANDS, Ecuador (AP) — Scientists have spent time diving with whale sharks in the Galapagos Islands to help solve some of the most enduring mysteries about the biggest shark in the sea.

Despite typically being bigger than a double-decker bus, the elusive whale shark has only tiny, almost useless teeth. It's also one of the least understood animals in the oceans.

Last year scientists tried some never-before used techniques on the species in the wild: taking blood samples and ultrasound exams. They're planning further expeditions to the Galapagos later this year to continue their research.

The Galapagos are among the few places in the world where presumably pregnant whale sharks are seen. Identifying where whale sharks are giving birth — possibly in or around the Galapagos — could help scientists protect the endangered shark.