A mental gland is a part of the body found in many species of amphibians and reptiles.
Mental glands produce chemicals that conspecific animals use to communicate.
The secretions from mental glands have been implicated in mate selection, species identification, and other functions.
[1][3][4] Scientists believe that the head bobbing behavior observed in turtles encountering another member of their own species may serve to disperse the chemicals from the mental glands through the air.
[1][2] In 2021, one team of scientists found that most turtles that have mental glands are aquatic.