Respiratory and cardiac activity of killer whales.

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Abstract
Orca in Puget Sound and San Juan Islands usually surface every 4-5 min taking 2-5 breaths at 5-10 sec intervals; 12-min soundings were observed. A confined undisturbed 6. 56 m, 3, 414-kg male averaged respiratory periods of 56. 5 sec. A 4. 27-m, 1, 090-kg female beached for respiratory flow curves, recorded from a calibrated "basket" pneumotachygraph, showed a tidal volume averaging 46. 2 liters; expiration duration averaged 0. 59 sec, 129 liters/sec peak flow; inspiration, blowhole expanded, 0. 75 sec, 90. 2 liters/sec. A suction-cup electrode attached to an electrocardiograph by insulated wires gave heart rates at 60 beats/min just before to 15 sec after the blow, switching to 30/min when submerged. Male and female ECG''s [electrocardiogram] disclosed no P wave, an inverted T wave, and simple R wave. Phonations caused dilation of nasal sacs aside the blowhole. Male and female sounds are distinctive. Phonation signals last 0.25-5 sec, the fundamental from 340-1,400 cycles/sec with defined harmonics extending to at least 70 kc. The variations of heart rate are discussed in relationship to sinus tachycardia of man.