Expression of CAs in different tissues and stages, juvenile stages. (a) Heatmap representation of RNA-Seq expression profiles of CAs in different developmental stages and body parts of S. ciliatum. Expression level for each gene and stage or body part was calculated as a sum of the posterior probability of each read coming from that gene over all reads  and adjusted with size factors of the RNASeq libraries . Statistically significant higher expression in the apical (top) region of the non-reproductive sponges in comparison to the middle or basal part is indicated by asterisks (‘m’ in comparison to the middle, ‘b’ in comparison to the base). The statistical significance was assessed using the adjusted p-value from DESeq package (p-value adjusted for multiple testing), padj ≤0.1.RNA-Seq. (b) Postlarval stages of S. ciliatum with only diactine (left) and diactine and triactine spicules (right). Arrows point at sclerocytes.