We’re used to getting our energy and building blocks from our food. Plants get their energy from the sun, and their building blocks from the air (CO2). They get water and some minerals, but a plant is made up off solidified air. It’s like if you could be solar powered living off just air, water, and an occasional multi-vitamin.

Anyway, carnivores don’t really get energy from their prey, just the nutrients. It’s like self fertilizing.