Nice ideas, and fun to do, although I spotted three group connections immediately, I feel like I actually sorted the groups by accident more than deduction, as there were at least two pairs that could be swapped between groups. The Nixie and Selkie groups are fun, but not sufficiently different from each other - Nixie and Selkie could be directly swapped over between their respective groups as they both fullfil the criteria for both. Similarly, ermine and sable are interchangeable between their two groups. The grid isn't valid, which is a shame, as I enjoyed for the most part