Discovery of an unusual rectal gland in the Atlantic sixgill shark Hexanchus vitulus led us to examine the rectal glands of 31 species of sharks to study diversity in rectal‐gland morphology. Twenty‐four of 31 species of sharks had digitiform glands (mean width–length ratio ± SD = 0.17 ± 0.04) previously assumed to be characteristic of all elasmobranchs regardless of habitat depth or phylogenetic age. Rectal glands from the fa...