The tetraphyllideans are common parasites of elasmobranchs, but their life cycles are largely unknown. They are most famous for the elaborate bothridia on their scoleces, whose pattern of depressions seems to match the topography of the particular region of the spiral valve where they are found. This has been presented as an example of extreme morphological adaptation of the parasite to the host, and as a mechanism to localize different species in different parts of the host to minimize interspecific competition.