What is "tandu"

The Tandu are a fictional extraterrestrial species from David Brin's Uplift Universe. Physically they are a spindly insectoid species. They are capable of regenerating severed limbs and even heads. If forced to humiliate itself by conversing with a member of an alien species as an equal, a Tandu will cut off one or two of its own legs as a form of ritual purification. A Tandu who has been deemed by his superiors to have failed unforgivably is expected to commit " suicide" by cutting off his own head (the body survives and eventually grows back a new head, but presumably the original personality dies with the brain).