Light micrographs showing the morphologies of living spionid larvae of genera Pseudopolydora and Spio A, B Pseudopolydora aff. achaeta, dorsal view of 12‐chaetiger (A) and 25‐chetiger larvae (B) C Pseudopolydora cf. kempi, dorsolateral view of 12‐chetiger larva D Pseudopolydora paucibranchiata, dorsal view of 13‐chaetiger larva E, F Pseudopolydora cf. reticulata, dorsal view of 17‐chaetiger (E) and 16‐chaetiger larvae (F) G, H Pseudopolydora tsubaki, dorsal view of 5‐chaetiger (G) and 11‐chaetiger larvae (H) I Pseudopolydora sp., dorsal view of 7‐chaetiger larva J, K Spio sp. 1, dorsal view of 8‐chaetiger (J) and lateral view of 12‐chaetiger larvae (K) L–N Spio sp. 2, dorsal view of 10‐chaetiger (L) and 17‐chaetiger larvae (M), and 17‐chaetiger metamorphosing larvae (N). Scale bars: 300 μm.