Expression of SA8 genes across functional regions in T. stephensoni (n = 3). Each graph shows the tissue-specific expression pattern of a transcript that corresponds to a SA8 gene. One transcript corresponds to two SA8 genes (SA8_clustered_2&7) in T. stephensoni. Bars represent the mean trimmed mean of the M-values (TMM) normalised expression value of the SA8 transcript in each anatomical structure, with error bars representing the standard deviation. Supporting data values are available in Additional File 3 : File S1. Abbreviations: A, acrorhagi; C, club-tips; T, tentacle; P, actinopharynx; M, mesenterial filaments; B, body column; PD, pedal disc