Body contact and synchronous diving in long-finned pilot whales.

Highlights: [•] Synchronous diving behavior of pilot whales was revealed using animal-borne devices. [•] Constant vertical distance between whales was maintained by vertical speed adjustment. [•] One particular individual tended to be the initiator of the synchronous dives. [•] The animal-borne camera recorded body contact; the primary type was flipper-to-body. [•] Animal-borne devices are powerful tools for studying underwater social interactions. [Copyright &y& Elsevier]