Figure 29 in The morphological and functional variability of pleon-holding mechanisms in selected Eubrachyura (Crustacea: Decapoda)

Figure 29. Schematic drawings of the structures contributing to pleon-holding and the pleon movements involved in unfastening the pleon. a-c: Press-button mechanism. (a) Pleon inside sterno-abdominal cavity, fastened by button structures (red), ventral view. (b) Pleon moved towards anterior, buttons disengaged. (c) Cross-section through sternite 5 with unciform button pointing towards anterior (red) and pleonal socket on pleon segment 6 folded over the button. Arrow indicates pleon movement to disengage press-button mechanism. d-e: Overhanging edge system. (d) Telson underneath overhanging edge (red) of sterno-abdominal cavity on sternite 4, ventral view. (e) Telson removed from underneath the edge by movement towards posterior. f-g: Wet adhesion via moisture and dense setal covering. (f) Overview of pleon with marginal setae (red) and setal patches on sternal plates (orange) inside sterno-abdominal cavity. Movement to break contact unclear. (g) Cross-section of contact between sternite 5 and pleon segment 6 facilitated by setae and water in between (wet adhesion). Black: pleon; blue: water; dark grey: border of sternoabdominal cavity/edge of telson underneath overhanging edge; light grey: sutures between sternal plates; P6: pleon segment 6; red/orange: structures contributing to functional pleon holding; S5: sternite 5.