Fig. 1

Morphology and relative size of ANGs across different cephalopod species. The ANG is shown attached to the ink sac in females of the golden cuttlefish (A), swordtip squid (B), and bigfin reef squid (C). The relative size of the ANG is quantified as the ANG-somatic index (D). Lowercase letters denote significant differences as determined by one-way ANOVA followed by Tukey’s multiple comparison test (P < 0.05). ANG, accessory nidamental gland; Gi, gill; IS, ink sac; LO, light organ; NG, nidamental gland; OG, oviductal gland; Ov, ovary, Se, golden cuttlefish; Ue, swordtip squid; Sl, bigfin reef squid