Here is the full list of all 18 Crab Dub achievements.
Start game for the Crab!
First zone completed!
Second zone completed!
Third zone completed!
Kill one Octopus
Jump 10 times on jellyfish
Inflate 10 kittens
Pop 100 bubbles
Use 10 hearts
Beat the game!
Unlock the final boss!
Chop 100 ice cubes!
Jump 100 times on a space donkey!
Start the game on the little duck!
Destroy 10 missiles!
Start the game in space!
Activate the magic pill!
Destroy 10 apples