Fig. 5

Berghia stephanieae juvenile digestion. Video stills (A, B) and cartoons (C, D) showing the peristaltic expansion and contraction of the digestive gland (grey outline) in a B. stephanieae juvenile over the course of one second (6.20–7.20 s in Additional file 2: Video 1), which occurs to move food to the distal ends of the diverticula. A and C show the expansion (teal arrows) of the primary digestive gland mass in the center of the animal, along with the contraction (pink arrows) of the diverticula. B and D show the subsequent contraction of the primary digestive gland mass in the center of the animal, along with the expansion of the diverticula. The cnidosacs (purple, C–D) do not fluctuate in size. Abbreviations: cs, cnidosac; dg, digestive gland; nem, nematocyst(s); tl, tail