Some characteristics of platypus diving:

• Platypi tend to have two types of dives:  short, active, feeding dives and longer, inactive dives.  During inactive dives, the animals usually rest on the stream bottom by wedging themselves under an object (Evans et al., 1994).

• Short, active dives average around a minute or less in length, whereas longer, inactive dives can last up to 11 minutes, although the average is closer to three minutes (Evans et al., 1994; Jones et al., 1987).

• The ratio of dive:surface time can range from 2:1 to 20:1.  Surprisingly, there is no correlation between time spent diving and time spent at the surface recovering (Jones et al., 1987).  While feeding, platypi will dive repeatedly over several hours (Bethge, 1997).

• During all dives, heart rate decreases significantly (bradycardia).  This is generally thought to conserve oxygen stored in hemoglobin by decreasing the rate of blood circulation to the tissues.
• In short, active dives, heart rate is decreased but erratic.  There is significant post-dive tachycardia (increase in heart rate), possibly to compensate for oxygen debt accumulated in the tissues.
• In long, inactive dives, heart rate is lower and more stable.  There is no post-dive tachycardia (Evans et al., 1994).