22.3 Wednesday, Jan. 4 Comparative functional capacity of adhesion and climbing among sicydiine gobiid fishes and related species MAIE, Takashi*; SCHOENFUSS, Heiko H.; BLOB, Richard W.; Clemson Univ.; St. Cloud State Univ.; Clemson Univ. email@example.com
Sicydiine and related goby species are able to adhere to surfaces using a ventral sucker (fused pelvic fins). This sucker is used by juveniles of many amphidromous species as they scale waterfalls during upstream migration after embryonic development and oceanic dispersal. However, adults may still use pelvic suckers to resist flash floods, or to re-scale waterfalls if they are displaced. Adhesive performance of the pelvic sucker is expected to affect climbing ability and, thereby, impact in-stream distribution. We measured adhesive pressure and force across wide size ranges of species from Hawai’i, Dominica, and Japan including climbing and non-climbing species. Adhesion by suction is achieved via two different strategies: (1) small size and isometric (or negatively allometric) scaling of the sucker among sicydiines, vs (2) large size suckers with isometric to positively allometric growth among non-sicydiines. Because suction attachment force is proportional to the area of the sucker, the force of body mass that must be resisted might be expected to outpace adhesive capacity as fish grow. Thus, adult individuals might have decreased climbing capacity relative to juveniles. However, species using the first strategy (sicydiines) show greater adhesion, aiding their climbing capability throughout ontogeny. In contrast, species showing the second strategy are non-climbing or weakly climbing species in which adhesive ability may decrease with larger size. Moreover, among sicydiines examined, suction pressure and force are higher than expected if adhesion were strictly a function of sucker area. Adhesion by sicydiine pelvic suckers may be regulated by variation in pelvic musculoskeletal activity, complicating expectations based on sucker size. NSF IOS-0817794, 0817911.