Schematics of musculature within subregions of the gut in Echinoderes . (A-B) predicted antagonistic functions between muscles associated with the outer oral styles and the mouth cone external circular muscle. Red arrows mean contraction whereas blue arrows extension. (C) myoanatomy of the mouth cone and pharynx in lateral view, with ventral side to the right. (D) overview of myoanatomy in the pharynx and intestine, in ventral view, with anterior to the top. Color-code according with 3D reconstructions of Figures 2 and 8. The gut is depicted in light grey. Abbreviations: esm, esophagus muscles; gg, gut grid; hd, hindgut dilators; mce, mouth cone external circular muscle; mci, mouth cone internal circular muscle; mil, midgut inner longitudinal muscle; oos, outer oral style; osm, outer oral styles muscles; pcm, pharynx circular muscle fibers; phs, pharynx suspensor; pil, pharynx inner longitudinal muscle; pip, pharynx internal protractor; pms, pharynx muscular sheath; pop, pharynx outer protractor; pram, pharynx radial muscle fibers; prm, pharynx retractor muscle; psm, pharynx sheath muscles; sph, sphincter.