Diving rats

This is the same behavior I observed ages ago, when I tried out a prototype habitat with a moon pool; My intention was to give the hambros a never ending source of water. What I didn't anticipate is that being surrounded by water without coming to harm for so much time desensitized them to it somehow, eliminating their natural instinctive fear of drowning. The first time one of them dove out of the moon pool and swam around the bottom of the tank (probably disoriented) I just about had a heart attack. Before I could scoop him out he returned to the moon pool and climbed back inside.

I eliminated the moonpool from future habitats mainly for my own comfort; Even having seen rodents competently swimming around in (what is for them) deep water, then returning to the habitat, I don't think I could ever be convinced that they'd always be able to find their way back in. It didn't seem natural, or reliably safe, and having a big open pool inside the habitat made it impossible to keep humidity down. Aside from their apparent willingness to take a dip, hamsters like to be dry. So, no more moon pools.

These rats, by comparison, obviously have a better idea of what they're doing. This most likely owes to their vastly better eyesight. I have much more confidence in a rat's ability to make (relatively) intelligent decisions concerning when to dive outside the habitat, and how to get back inside. Building a special, moonpool accessible habitat just for rats might be a fun experiment. It looks like I would never have to surface it; Feeding them would be as simple as dropping vegetables (like the pea in the video) to the bottom of the tank, near the habitat. The idea of competent rodent aquanauts who understand how to return to/leave their own pressurized underwater living space is pretty neat in a Secret of Nimh way. At that point it seems feasible to put a much larger habitat in an outdoor pond or lake, running a power cord from the air compressor to the grid, and let the rats come and go as they please.