Anaerobic respiration does not involve oxygen. It happens when you do vigorous exercise and your body can’t supply enough oxygen to your muscles. Anaerobic respiration is the complete breakdown of glucose into lactic acid:
Glucose → lactic acid + energy
Anaerobic = without oxygen
The anaconda robbed (anaerobic) the ox of oxygen (without oxygen).
No Oxygen for the Ox because its glued to the ground and lacks oxygen (lactic acid)