A passive treadmill was designed and built that measures the speed of lobster
walking, while simultaneously recording heart and scaphognathite pumping
rates. The treadmill only moved when the lobster voluntarily walked either
forward or backward. Lobsters (n = 5) on the
treadmill typically walked in bouts lasting an average of 5 min (range 8 s to
53 min). During these bouts, the mean walking rate was 0.9 0.6 m/min
(n = 100 bouts from 5 lobsters), and the maximum
speed recorded was 2.5 m/min. At the onset of walking, and sometimes
5–10 s before, the heart and ventilation rates rapidly increased.
Ventilation rate increased more than heart rate during walking (ventilation
rate: 194% increase; heart rate: 69% increase) and returned to
baseline faster (4.5 3.9 min) than heart rate (6.6 3.9 min) after a bout.
Heart and ventilation rates during walking do not appear to be related to the
duration of the bout. Heart and ventilation rates were positively correlated
with the average walking speed attained in 3 of the 5 lobsters tested. Heart
rate, in particular, appeared to have an upper limit of approximately
90–100 beats/min, regardless of walking duration or speed.
