They reproduced by spores, known as 'sarlacci,' that traveled through space until they found another suitable planet to inhabit.
The most infamous sarlacc lived on Tatooine. The Tatooine Sarlacc as depicted in Super Star Wars, The sound of the sarlacc in Return of the Jedi was created from sounds of alligator hisses, as well as the sounds of some of the Jedi crew's stomachs after eating pizza.
