I've seen them when I was looking for birds but if you don't see them, check your setting

Don't push me: Tap on a crab until you have the achievement
What a big bird: Tap the airplane's shadow 10 times
Just bloating: Reach the finish line without collecting a single gear
Murk-Maker: Tap the water 500 times
I'm a shark: Scare fish 300 times
Figure it out for yourself: turn down 200 regular tourists
Gift of gab: Tap 100 tourist while small talking
The easy way out: Complete a task for crystals in any massive project