Table 1 Bivalve larval retractors and the terms used in the literature and herein. Muscles in the same line indicate proposed homology across species. Data based on the study herein (Nodipecten nodosus) as well as on Cragg [21] (Pecten maximus) and Wurzinger-Mayer et al. [20] (Lyrodus pedicellatus)

Velum retractors

Dorsal velum retractor

Velum retractor 1

Dorsal velum retractor

Medio-dorsal velum retractor

Velum retractor 2

Ventral velum retractor

Medio-ventral velum retractor

Velum retractor 3

-

Ventral velum retractor

Velum retractor 4

-

Ventral larval retractors

Posterior ventral larval retractor

Posterior retractor 1

Ventral larval retractor

Anterior ventral larval retractor

Posterior retractor 2

-

-

Posterior retractor 3

-