Vx.-AX G. S-K THE SYSTEMATIC IMPORTANCE OF STOMACH ANATOMY IN BEAKED WHALES

The stomachs of Cetacea are generally uniform in their anatomy. The stomach of a bottlenose dolphin differs only in size from the stomach of a blue whale. The stomach chambers consist of the forestomach, main stomach, connecting channel and two pyloric stomach compartments. The only known exceptions to this general scheme are some of the river dolphins and the beaked whales. The forestomach is lacking and the pyloric stomach compartments number greater than two in all five genera of beaked whales. The functional significance of this is unknown but it may lead to a better understanding of beaked whale relationships. Two summers were spent in Wadaura, Chiba Prefecture, where there was an active fishery for Baird's beaked whales. A detailed examination of the stomachs of 29 specimens was done. Examination of the scientific literature for the count of pyloric compartments in beaked whales gave conflicting results due to the lack of standardized terminology. Most of the conflicts seem to arise from differences in defining the compartments at the proximal and distal ends of the pyloric chambers. INTRODUCTION Beaked whales form the odontocete family Ziphiidae. The systematic • 1 X; 7-7 >OT5E3T (Smithsonian Institution, USA) HB£«#£%0f3EJ5T*8£ No.4 1.993^ (IBI REPORTS No.4, 1993)