Comparative summary of gene expression in cell and organ territories during embryonic and larval development in Capitella teleta. (A) Schematic illustrations of early embryonic stages and a table comparing the presence or absence of detectable gene expression in selected blastomere and germ layer regions. (B) Schematic illustrations of post-gastrula and larval stages and a table comparing the presence or absence of gene expression in selected tissues and organs associated with gut formation. Schematic stages are oriented in ventral view with anterior to the left. The colored names and ovals identify C. teleta orthologs of the five core genes in the endomesoderm GRN ‘kernel’ of the sea urchin. The five orthologs in (A) and (B) are separated by a dashed line from three additional C. teleta genes characterized in this study. The gray shading represents endoderm. Abbreviations: ant, anterior; bp, blastopore; br, brain; cns, central nervous system; ec, ectoderm; en, endoderm; fg, foregut; hg, hindgut; mg, midgut; mo, mouth; pos, posterior; St, stage; 1 m, 1st quartet micromere; 1 M, 1st quartet macromere; 3 m, 3rd quartet micromeres; 3 M, 3rd quartet macromeres. Dotted line in stage 3 gastrula indicates the position of the blastopore. Thin solid lines internal to the contour of the body in stages 3, 4 and 6 indicate the inner boundary of regions of ectoderm distinguished by low yolk content.