My VERY late half of the design trade with theloinlesslioness! I did it sort of in the style of someone doing field sketches of the animals (which I have not named—I’ll leave that up to their new owner :) ).
These guys are about the size of flying squirrels. They are arboreal and aquatic, doing their breeding in trees but most of their hunting (insects, toads, and small fishes) underwater. They use their patagium both to glide from tree to tree and to “fly” underwater, as do manta rays. The species is socially monogamous, meaning that they remain paired during the breeding season and both care for offspring, though both may try to increase their reproductive opportunity when possible with outside males/females. The male courts the female in breeding season by performing a tail-waving and patagium-flaring display. The females are slightly larger than males, and after giving birth to pups (usually only 2-3 at a time, which are very altricial) do almost all of the hunting for the pair while the male cares for the brood. The male has a patch of long fluffy fur on his chest that he uses to keep the pups warm early on, as they cannot thermoregulate yet. The pups remain in the nest for about a month, after which they begin to explore their home tree. This is the most dangerous part of the pups life, as they learn to glide and eventually swim. While these critters are obligate air breathers, they have simple gill structures allowing them to stay under water much longer than typical mammals.
The average life span is ~7 years in the wild, but up to 15 in captivity. However it is notoriously difficult to breed them in captivity, as the females are very picky.
I hope you like these little fellas, Al, and I hope you don’t mind the long and nerdy species description! :)