MARSHALL, C.D.*; DEHNHARDT, G.; Texas A&M University at Galveston; Ruhr-Universit�t Bochum: Suction Capability and Performance in Feeding Harbor Seals (Phoca vitulina)

Measures of suction generation capability in harbor seals were collected as part of a comparative study on the feeding performance of pinnipeds. Although suction is thought to be an important component of the feeding repertoire in harbor seals there are no data to support or refute this premise. Three harbor seals were presented pieces of fish in an experimental apparatus that forced seals to choose between ingesting fish by biting or suction. A Millar MPC 350 pressure transducer and portable electrophysiological recording system was used to collect pressure forces during feeding. Feeding behavior was videotaped and synchronized with physiological data using a pair of flashing LED lights that generated a corresponding square wave pattern. Harbor seals used suction, biting, and some hydraulic jetting when feeding from the apparatus. The mean suction force recorded was �11.3 kPa (S.D. +/- 7.59). The maximum suction pressure measured over 352 feeding events was -46.3 kPa. The mean duration of suction events were 0.6 s (S.D. +/- 0.36) and ranged from 0.1 s to 2.06 s. A positive pressure preparatory phase often preceded the main suction event. In some instances a small post-suction event positive in pressure was observed. These supplemental phases presumably served to remove excess water from the mouth either just before or just after a suction event. Suction capability of harbor seal in this study were considerably smaller in magnitude compared to suction specialists such as bearded seals and walruses, but were strong enough to be an important component of the feeding repertoire.