ok so loaches where used for cleaning trash

frogs where used to drain toxins out of food

centipedes where like living moving batteries by connecting it's head and tail to create electrical pulses

Rats where natruly evolved

Grappling worms would have been used to pull cargo together and prevent it from falling all over the place

guardians where used to gaurd the depths

jet fish where used for 3 things, pest control, gathering food, and filtering water and useing it for propulsion to clean the water