Hmm, just as a point of discussion, I just went to go explore the XML files, and The Whale Shark has a set that doesn't exist with any other animal. Usually, an animal has a main one, and then a set of Adult ones, and then a set of Young ones. The Whale Shark also has a set of ones labeled as "old". Whether you've seen them grow or not, I can almost say for sure that they do. It may take several years, but it'll happen. I'll report back with anything else I find.
Edit: the Adult model is scaled at 0.9, the "Old" model is scaled at 1.4