By an Anonymous Contributor and Alex Irpan

Alex: Most of the ideas for this puzzle came from the anonymous contributor. They didn't know any My Little Pony, and since we needed a Fluttershy puzzle, I suggested theming it after "Find a Pet", and it went from there.

The letter-rotating step was primarily done to fit Tank into the puzzle, since he's the point of the entire episode. As a side benefit, it spread the animals over more of the alphabet, which made the dichotomous key easier to build. As much as possible, I wanted the Yes/No questions to be based on the animal, rather than their name, especially because the names were ambiguous before solvers figured out the "Find a Pet" connection. I wasn't able to do this all the way, but I'm happy I was able to bring it down to just 2 questions based on spelling instead of semantics.

Unfortunately, one side effect was that TORTOISE was also an 8-letter phrase. During the hunt, many solvers wanted to treat TORTOISE as a Vigenere cipher key to shift each of the 8 leftover pets by a different value. We didn't catch this in testsolving because every testsolve group brute-forced all 26 shifts first, solving the final step immediately. Some solvers also interpreted "Rotate" as "anagram". The ciphertext of "IRARGVNA" is very close to an anagram of VIRGINIA, if you assume you have a few errors.

Given a do-over, I would probably just remove Tank from the puzzle. It's unfortunate from an MLP perspective, but it makes the solve cleaner.

With an 8 letter clue phrase, even a few errors could make the message unreadable, so we added the "not supposed to get here" labels to every letter that shouldn't be reached. Here are some examples that we designed the dichotomous key to catch.

Unfortunately, some names (like "yellowjacket") weren't caught by this, but the letters become distinctive once the song connection is found.

I was concerned that telling solvers the letters used would enable a shortcut to the puzzle: check all letters that are used, build an appropriate regex of length 8, and see what words match. After some discussion with testsolvers, we decided the Caeser shifting made this too difficulty, or at least, hard enough that we were okay with solvers finishing the puzzle that way.

(Incidentally, in the alternate universe where we didn't Caeser shift VENETIAN, a regex search for 8 letters all inside [PETSLEFTVENETIAN] would find VENETIAN at the 11th full word of nutrimatic results, so our fears weren't entirely unfounded.)

Factchecking the dichotomous key was pretty time consuming, and while doing so, we learned many fun facts about animals.

• Bunnies are not daytime creatures (diurnal), nor are they nighttime creatures (nocturnal). They're twilight creatures (crepuscular).
• Ladybugs are not nocturnal, but the top Google search result incorrectly describes them as nocturnal, due to using the wrong definition.
• Rabbits do not eat wood, but they do chew on wood pellets.
• Hummingbirds have been spotted digging through wood ashes, and may even eat wood ashes, as a source of calcium and other minerals.
• Otters are nocturnal.
• Crickets are nocturnal.
• Rabbits can swim, but don't like doing so.
• Bats can swim.
• Eagles and bunnies both have 4 toes.
• Bunnies cannot turn their head 270 degrees, but they can rotate their ears 270 degrees, and can rotate each ear independently.
• Owls are carnivores, hummingbirds are omnivores, and bats are either omnivores or carnivores depending on the species.
• Hummingbirds and bats do, in fact, have kidneys.

As for the errata, they were issued because:

• Thorax is a general term for the chest of an animal, and not an insect-specific term.
• We incorrectly assumed that only cats were scared of cucumbers. Turns out wasps are repelled by freshly sliced cucumbers, due to the smell they emit, which is undetectable by humans.
• Although owls are the only animal in the puzzle that can rotate their head 270 degrees in one direction, we realized the clue was a bit ambiguous, because it could also be interpreted as rotating 135 degrees in either direction for a total arc of 270 degrees.

We hope you also learned fun facts about animals while solving this puzzle!