Here is the full list of all 26 Mayhem Survivors: Animals achievements.
Reach 40% Armor
Feed 10000 Animals
You have fed 30000 Animals
You have fed 50000 Animals
You have survived for 15 minutes
You have survived for 30 minutes
You have survived for 60 minutes
You have survived for 15 rounds
You have survived for 45 rounds
You have survived for 90 rounds
You have survived for 20 waves
You have survived for 60 waves
You have survived for 100 waves
You have opened 100 Chests!
Level Up 250 times
Buy 1000 upgrades from the Market
You have defeated a Boss Animal
You have defeated 5 Boss Animals
Fully upgrade your weapon for 50 times
Upgrade your weapon to a max level
Equip 500 Upgrades
Reach 40% Dodge
Reach 140 Speed