Platypus resting under the dome.
Platypus like sleeping underwater, but only if they can find a "rest"
to jam their body under to prevent it from floating to the surface.
We discovered this when two males in hte same tank we seen to be vying
for the same position at the bottom of the tank under a projecting pipe.
When we provided artificial rests, platpus spend a lot of time there. One
spent 8 min sleeping in one bout before coming to the surface for
a breather.
We installed the plastic dome in the centre of the arena after watching Carl Hopkin's electric fish take shelter under the infra-red transparent dome at the centre of his arena.
The platypus would dose cooperatively under the doem while we presented electrical stimuli. We could judge the sensitivity and directionality of platypus electroreception by varying the strength and position of the stimulus and watching the reflex head saccade that platypus give for every detectable stimulus.