Swimming in the Antarctic scallop Adamussium colbecki: analysis of in situvideo recordings

Swimming activity of the Antarctic scallop at a temperature of c. -1.4 degr ees C was analysed using in situ video recordings obtained from a remotely operated vehicle (ROV) in Terra Nova Bay, Ross Sea. Data are presented on s wimming trajectories, distance travelled and velocity during a swimming bou t, adduction frequency, shell gape angle, and the angular opening and closi ng velocities of shell. This scallop is an effective swimmer although swimm ing bouts in response to the ROV were generally short, consisting of 2-5 ad duction cycles in the take-off phase followed by 1-4 (exceptionally 14) add uctions during level swimming. The maximum velocity during each adduction c ycle ranged from 19.4-43.1 cm s(-1) and the mean velocity during a swimming bout from 12.0-23.5 cm s(-1). Each adduction cycle consists of opening, cl osing and glide phases of approximately equal duration. Adduction frequency during swimming averaged 1.5 adductions s(-1).