Imagine an alien world populated by silicon based lifeforms, the mega fauna can only be animated by exposure to adequate lights from the star or the moon. This world concept is inspired by a automatronic killer giant doll in a mega hit Korean TV series, so I design all the creatures to only become animated when it receives sufficient energy from the electromagnetic radiation at specific threshold but I couldn't come up with a sound evolution driver that this mechanic can triumph over our familiar metabolic system where energy comes from food we ingested and excess is stored as fat. I am not sure why nature would prefer it this way over cat and mouse aka survival of the fittest where species evolve certain traits to aid them to eat others or to avoid being eaten, is my species doomed to extinction if they never adopt metabolic lifestyle?
Creatures that become alive only with enough sunlight basically describes any deciduous plant. When winter and its short and cloudy days come, being alive becomes a liability. Better wait for summer and its long sunny days.
Independently from being carbon or silicon based.
Junk Yard Dogs:
Light is the basis of the food chain, whether it is chemically stored first or directly used. That would need to be some fairly intense light, or the organisms would move slowly in the dark and increasingly faster in the light. Usually, light is not a very dense form of energy in most places (but it could be - imagine organisms living on something like Mercury, although that brings it's own problems).
A biochemically-driven species on your planet would die, because the biochemical system depends on biochemical energy in it's food sources. There would simply be nothing to eat. Energy in your system isn't biochemical. It would be like a person trying to eat a car. But a car (even a solar-powered one) can move, and takes lots of energy to build, as do the parts that go into it. So parts form the basis of your food chain.
If animated species (read "herbivores") depended on difficult to manufacture/energetically costly components (like solar collectors) from passive species (read "plants"), then they would still be supplied by solar energy, but need to move so they could take advantage of resources. Species (read "predators") that obtained components from the richer, motive sources (the herbivores) would hunt.
Perhaps optical storage systems that store light and gradually absorb it slowly would give some species a competitive advantage. The "Waste" of the light in such a battery would actually be the absorbance of the energy over time. This way, a species could have a "light capacitor" that would prevent them from being immobilized the moment they went into a shadow (which suggests interesting hunting techniques...)
Mirrors would be extremely critical parts of species, so they could shelter in the dark or concentrate light onto absorptive surfaces while still obtaining energy. If the light is hot and intense, organisms may need to limit their exposure so components are not damaged by long-term overheating or radiation. Mirrors and reflective surfaces could be protective, as well.
So while energy is still the basis of the food chain, it comes from the increasingly predatory species operating with higher efficiency and sophistication due to the increasing concentration of quality components and taking advantage of the "lesser" species. The energy of "plants" is stored in components, not chemical batteries.
Crystal radio creatures.
A crystal radio receiver, also called a crystal set, is a simple radio receiver, popular in the early days of radio. It uses only the power of the received radio signal to produce sound, needing no external power. It is named for its most important component, a crystal detector, originally made from a piece of crystalline mineral such as galena.1
Your creatures live on a world where chemistry does not lend itself to oxidation / reduction types of life. But there is ample radio energy from their star. The creatures are in essence crystal radios. We oxidize reduced carbon and use the resulting energy to make electrical signals and contractions so that we might dance the merry jigs we dance. Crystal radios (and silicon carbide is an acceptable crystal for this) turn radio energy into electrical current. The depicted set produces enough energy from radio waves to power the headphones attached. I have seen a crystal radio that powered an LED. Your creatures use radio energy turned into electrical energy to power their activities.
There would, it seems to me, still be evolutionary benefit in being able to store energy so your crystal creatures could dance their merry jigs at night. It also seems to me there would be benefit in animals not needing to sleep so we could dance our merry jigs all night. Yet all animals sleep. So too your crystal beasts. They are up when the sun is up, jigging their crystal selves around with radio wave power. When the sun goes down they fall asleep.
You are basically describing plants, but with two twists:
- those beings move
- those beings don't store energy
Plants usually don't move, because it takes a huge amount of energy and sunlight doesn't provide a lot of energy density. So during the winter they turn on power save mode instead of migrating.
If your planet is exposed to intense sunlight (giving plants enough energy to move) and a very slow day/night cycle with super frosty nights, it might cause plants to move to keep tracking the sun. But then again, with these circumstances the current day side will probably be incredibly hot and will kill all living things there. So maybe the plants will chase the twilight zone of the planet?
Regarding the energy storage point: It would be a huge disadvantage for a creature not to be able to store energy, since walking into shadow would be equal to death. That's not really advantageous.
A planet with a very long day/night cycle
Basically, this is a planet where each day or night is an entire season.
On Earth, it is normal for plants to shut down in the winter, which creates a chain reaction through the entire food chain - many animals either migrate, hibernate, or in the case of many insects simply die off and leave their eggs to re-awaken in the spring.
But plants and animals on Earth can't simply use the presence or absence of light to trigger these behavioral changes, since day and night still happen in both the summer and winter. They use a complex system of recognizing when the days are shortening and the temperature getting colder to determine when it is time to enter the winter-phase behavior. In addition, there are evergreen plants that can survive the cold, so some animals might still stay awake - food is more scarce in the winter, but not completely absent.
On a planet where day and night are essentially seasons, the difference between summer and winter would be even more extreme - there would be no "evergreens" adapted to resist the cold, because there's no sunlight anyway. During the night, all plants would hibernate or die, and all animals would need to do one or the other (unless they could migrate around the entire planet every cycle). For hibernators, the process could be triggered simply by the absence of light, because day and night define the "seasons", rather than merely being altered by them.