I have this idea for a world where the creatures, though they look organic externally, are actually mechanical in nature and when damaged reveal their mechanical innards, with pipes pumping coolant instead of veins pumping blood, the damage usually damaging the pipes and making them 'bleed' their coolant, and some sort of energy acquisition system as part of their bodies that necessitates the coolant being pumped.
They can reproduce by means of a small factory in 'female' units receiving slightly randomized transmitted blueprints of themselves from 'male' units that are compared with the female's blueprint and interlaced with the male's blueprints to allow evolution, and grow by means of structural/system stages that activate over time and extends limbs, decompacts/bulks-up the frame, dedicates more power to the limbs because their algorithm is obviously efficient in resource acquisition to have survived this long and make the 'adults' stronger than the 'young', etc, and eventually die on their own by means of the mechanical structures breaking down over time.
Due to these creatures being mechanical in nature, they can have abilities that are unlikely, if not impossible, for organic creatures to have, and is the primary reason for why the human-like machines in this world need to be rather clever in fighting things that can make electricity arc like a Tesla coil or can lift boulders and fling them like it's nothing. The female units can 'eat' mineral compounds and other resources, which is what they use as the resources for their factories.
The only organic lifeforms on this world are plants, who introduce energy to the 'ecosystem' by their usual means of growth and photosynthesis.
I already have 'herbivores' that eat the naturally growing plants and burn them in a furnace stomach and converts the heat energy to stored electrical energy via water that has been previously taken in being heated up and turning to steam to run turbines where a creature's lungs would be and vent any excess steam by 'breathing out' if they took in too much water earlier. As was discussed in comments: I am open to different herbivores performing different forms of resource processing and energy acquisition, like condensing plant matter into fuel and using combustion engines to make energy.
My problem comes with making predators in this world. Since they can't get energy from plants like the herbivores, how would they go about extracting the energy from the herbivores after killing/overpowering them?