Glue Secretion and Adhesion by Larvae of Sailfin Shiner (Pteronotropis hypselopterus)

Abstract

Pteronotropis hypselopterus (sailfin shiner) larvae attached to submerged objects with an elastic glue secreted from two pores located on their heads. The cement pores were located ventrally in hatchlings and migrated in an anterior and dorsal direction through a subterminal to a terminal position as larvae grew. Larvae were adhesive and sedentary during the developmental interval from hatching until swimup. Pteronotropis hypselopterus offspring were supplied solely by an endogenous energy source (yolk) throughout this entire developmental interval. During this interval, concurrently, yolk was depleted; the yolksac became more stream lined; and gill structures, mouth parts, lining of the gut, and posterior swimbladder all formed. Development of these features while larvae were adhesive and the subsequent inflation of the posterior swimbladder and movement into the water column were precursors to initial feeding and transition to a solely exogenous energy source. A brief period of overlap between endogenous and exogenous nourishment frequently occurred after swim-up. Adhesion and the sedentary behavior may help the young, poorly developed larvae to maintain their position in flowing water, while conserving endogenous energy stores for growth and development. Benefits may also include avoidance of predators and anoxic sediments.