How to get
A Limited Edition Pet  attained from purchasing a kick start pack originally released on the week of August 8th, 2015 or is available for 3 days to all new players. It is a type of decor that does an animation when you tap it.
210 Gems + King Crab for $2.99 USD.
You can now also adopt the King Crab using stickers at the Pet Sanctuary.
Combining King and Queen Crab
When you have both the King Crab and Queen Crab their pet habitats will be joined together when placed side by side: