The four whales are: Fail Whale, Bowhead Whale, Cake Whale, and Sperm Whale. Of these whales, the Fail Whale costs 55 Island Cash but grants you an additional 2 energy. The other three whales only cost 40 Island Cash, but also only grant you 1 Max Energy. You can buy as many of these as you want, accumulating a ton of extra energy. The whales are placed on your home island, so not only do they provide an extra energy benefit, they also look good too!
These whales will only be in the store for 7 days. Hop on in to Treasure Isle to check them out.