You’d think it’s simple. Throw some water at a daisy, give a dog a bowl of kibble, and call it a day. But nature is kind of a diva. When we talk about what do plants and animals need, we aren't just talking about the bare minimum to keep their hearts beating or their cells dividing. We are talking about the complex, often invisible requirements that keep an ecosystem from collapsing into a pile of dust.
Biology is messy.
It’s easy to forget that a plant isn't just a green decoration. It’s a literal chemical factory. And animals? They’re basically high-maintenance biological machines that require specific inputs just to keep their internal chemistry from going haywire. Honestly, the more you look into it, the more you realize that survival is a constant balancing act. If one thing goes missing—even something tiny like a trace mineral or a specific wavelength of light—the whole system starts to stutter.
The Invisible Buffet: What Plants Are Actually Eating
Most people assume plants eat soil. They don't. A 17th-century scientist named Jan Baptista van Helmont actually proved this by growing a willow tree in a pot for five years. The tree gained 160 pounds, but the soil barely lost two ounces.
So, where did the mass come from? Air.
Plants need carbon dioxide more than almost anything else. They breathe it in through tiny pores called stomata. Using the energy from sunlight, they rip those carbon molecules apart and turn them into sugar. It’s called photosynthesis, and without it, we are all dead. Simple as that. But light isn’t just "light." Most plants are picky. They specifically crave the blue and red ends of the spectrum. This is why professional growers use those weird purple-tinted LEDs; they’re just giving the plants exactly what they want without wasting energy on the green light that plants mostly reflect anyway.
Water is the other big one. It’s the delivery truck. Without water, nutrients can’t move from the roots to the leaves. But water also provides structural support. Think about a wilted tulip. It’s not "tired." It has lost its turgor pressure. Basically, the water balloons inside its cells have deflated.
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Nutrients: The Big Three and the Tiny Others
Beyond the big stuff, plants need the "NPK" combo you see on fertilizer bags.
- Nitrogen for the green stuff (leaves).
- Phosphorus for the plumbing and the roots.
- Potassium for overall "fitness" and disease resistance.
But there’s also the weird stuff. Magnesium is the literal heart of the chlorophyll molecule. Without it, the plant can't capture sun. It’s like having a solar panel with no wiring. Boron, zinc, molybdenum—they need these in tiny, microscopic amounts, but if they aren't there, the plant grows deformed or just gives up.
The Animal Kingdom: It’s More Than Just Calories
Animals are different because they can't make their own food. We have to go find it, kill it, or pick it. This makes the question of what do plants and animals need much more complicated for the mobile side of the tree of life.
Animals need "macronutrients"—carbs, fats, and proteins—but the ratios are wildly different depending on who you are. A hummingbird needs a sugar rush every few minutes because its metabolism is screaming along at a pace that would melt a human’s internal organs. A python can eat a deer and then chill for a month.
But food is only half the battle. Oxygen is the non-negotiable. Whether you’re a fish pulling it out of the water with gills or a cheetah sprinting across the savanna, you need oxygen to burn those food calories for energy. It’s cellular respiration.
Shelter and the "Goldilocks Zone"
Animals also need a specific temperature range. We call it the "thermal neutral zone." For humans, it’s a comfortable room. For a desert pupfish, it might be water that feels like a hot tub. If an animal gets too hot, its proteins literally start to cook and unfold. If it gets too cold, the water in its cells can freeze and shatter the cell walls.
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Shelter isn't just a roof. It’s safety. An animal needs a place where it can sleep without being eaten. For a squirrel, that’s a drey high in a tree. For a bear, it’s a cave. Without a secure spot to rest, stress hormones like cortisol spike, and the animal’s immune system eventually fails. Chronic stress kills wild animals just as surely as a predator does.
Space: The Requirement Nobody Talks About
Both plants and animals need room. This is the part of the what do plants and animals need equation that humans usually mess up.
Plants need root space. If you cram a giant oak into a small planter, it becomes "root-bound" and eventually chokes itself out. They also need "air space" to prevent fungal infections.
Animals need "territory." This isn't just about being greedy. A mountain lion needs dozens of square miles to find enough deer to stay alive. When we fragment forests with roads, we are literally taking away a biological "need" as real as water or air. Without enough space, you get inbreeding, disease, and "island syndrome," where a population just slowly blinks out of existence because it has nowhere to go.
The Symbiosis Factor: Needing Each Other
Here is the kicker: plants and animals often need each other to survive.
About 80% of all flowering plants rely on animals for pollination. No bees? No apples. No bats? No agave. It’s a mutual dependency. Animals, in turn, need plants for the oxygen they breathe and the base of their food chain. Even a "pure" carnivore like a lion is basically just eating processed grass, because the zebra it ate spent its whole life munching on savanna stalks.
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And then there's the microbiome. You have trillions of bacteria in your gut. So does a cow. So does a termite. Without these tiny "animals" (microbes), a cow couldn't digest the cellulose in grass. It would starve to death on a full stomach.
Practical Steps for Supporting Local Life
If you’re looking to actually apply this knowledge—whether in your backyard or just in how you think about the planet—you have to look past the basics.
Stop "Cleaning" Everything
If you have a garden, leave the dead stalks and the fallen leaves. Insects need those for shelter. Birds need those insects for protein. By "cleaning" your yard, you’re removing a core survival need for the local food web.
Think About Wavelengths
If you’re growing plants indoors, don't just use a standard bulb. Get a full-spectrum light. Plants need those specific blue and red peaks to trigger their flowering and growth hormones.
Water Mindfully
Most people kill plants by overwatering. Roots need oxygen too. If the soil is constantly a swamp, the roots drown and rot. Let the soil dry out so air can reach the root zone.
Focus on Diversity
If you want to help animals, plant native species. A lawn is a "green desert." It provides zero food and zero specialized shelter for local wildlife. Planting even one native oak or a patch of milkweed provides the specific chemical needs that local insects and birds evolved to require.
Understanding what do plants and animals need is really about understanding connections. It’s never just one thing. It’s the interaction between the sun, the soil, the atmosphere, and the incredibly complex social and biological webs that tie every living thing together. Survival is a team sport.