Here is the full list of all 13 Sipho achievements.
First boss defeated
Second boss defeated
Third boss defeated
Fourth boss defeated
Saenus Beefuorus breed unlocked
Buginis breed unlocked
Cra'Than breed unlocked
Have a zooid from each breed
Beat a level without killing a single creature
Beat the game without growing a single weapon zooid
Kill a head in five seconds
Mycophorus breed unlocked