Eremophilus mutisii uses the vascularized central portion of its stomach for aerial respiration, and is a frequent but not obligatory air breather. Air ventilation takes place during a rapid dash to the surface with the expiration of old air preceding inspiration. The frequency of air breathing is affected by aquatic O2 concentration. E. mutisii can survive at least 10 days without air breathing in normoxic water but cannot survive without air access in water containing less than 2.0 ppm O2.