Figure 3 in Geochemistry drives the allometric growth of the hydrothermal vent tubeworm Riftia pachyptila (Annelida: Siboglinidae)

Figure 3. Summary of our findings on the allometric growth of Riftia pachyptila. A, all body parts, namely obturaculum (ob), vestimentum (vm), trunk (tr), and opisthosoma (op), are shorter in juveniles than in adults; the growth rate is higher for the trunk, and minimal for the opisthosoma (Hypothesis 1). The lines connect the body parts to make these differences even more evident. B, the different conditions between the basalt-hosted, sulphide-rich vents at 9 °EPR and 21 °N EPR, and the highly sedimented, sulphide-poor vents at 27 °N EPR in the Guaymas Basin affect the growth of each body part (Hypothesis 2). The 'fat' morphotype from basalt locations is characterized by the presence of thicker vestimentum (Ø vm), wider tube opening (Ø tb), longer trunk (L tr), and comparatively shorter obturaculum (L ob) and smaller number of tentacular lamellae (N lam). The 'slim' morphotype from the sedimented vents has thinner and shorter trunk, but longer tentacular crowns and higher number of lamellae. This variability might be adaptive and selected to keep the sulphide uptake near to the optimum values for the symbionts.