Meeting Abstract
Clione feed on actively-swimming shelled pteropods of the genus Limacina. Clione rapidly protract six buccal cones that surround and grip the prey. The surface of the buccal cones contains a dense coat of adhesive papillae, each made up of a rosette of upright spires. A single cell (Type 1 cell) forms the tip of each spire and contains a cluster of large secretory granules. A central process of the secretory cell extends medially through the muscular layers of the buccal cone and into the central hemocoelic space. A second type of secretory cell (Type 2 cell) is positioned next to the Type 1 cell in the spires and contains elongated, electron dense structures which are released near the tip of each spire as a flocculent material. Central processes of Type 2 cells extend into the center of the buccal cone in parallel with the Type 1 cells. One specimen of Clione was fixed while it gripped a Limacina. Following fixation, the prey shell was pulled from the buccal cones and both the shell of the prey and the points of contact on the buccal cones were examined. In the contact area, the tips of the spires were missing the packet of secretory granules and “packet ghosts” were found on the surface of the buccal cones. Similar packet ghosts were found on the Limacina shell in the region of contact with the buccal cones. Once a Clione captures a Limacina, the prey is manipulated by the buccal cones so the opening of the shell is over the predator’s mouth. This manipulation requires coordinated gripping and release of the prey. The two types of secretory cells in the spires of adhesive papillae may represent a duo-gland system that allows adhesion and de-adhesion of the buccal cones during prey manipulation.
