How Does the Nutrition in Plants Compare with the Nutrition in Animals?

December 9, 2025 •

4 min read

Over 99% of Earth's biomass is composed of plants, a staggering fact that underscores the fundamental difference in how does the nutrition in plants compare with the nutrition in animals. These two kingdoms of life have evolved distinct metabolic strategies to acquire the energy and matter needed for survival, growth, and reproduction.

Quick Summary

Plants and animals utilize vastly different strategies for acquiring sustenance. Plants are autotrophs, synthesizing organic compounds from sunlight and inorganic matter, whereas animals are heterotrophs, consuming other organisms for pre-made organic nutrients.

Key Points

Autotrophic vs. Heterotrophic: Plants are autotrophs, making their own food, while animals are heterotrophs, consuming other organisms for nutrients.
Energy Source: Plants use sunlight for energy via photosynthesis, while animals derive energy from the chemical bonds in the food they consume.
Nutrient Acquisition: Plants absorb simple inorganic minerals from the soil and carbon dioxide from the air. Animals ingest complex organic molecules like proteins, carbohydrates, and fats.
Carbohydrate Storage: Plants store excess glucose as starch, whereas animals store it as glycogen.
Digestive Systems: Animals have specialized digestive organs to process food, a system absent in plants where cellular-level synthesis occurs.
Shared Requirements: Both plants and animals require fundamental elements like carbon, hydrogen, and nitrogen, along with water and various minerals, for survival.
Ecological Interdependence: The nutritional differences are the basis for the food chain, where plants produce the oxygen and food that animals consume.

The Foundational Modes of Nutrition

At the core of the nutritional comparison between plants and animals lies the fundamental distinction in their modes of sustenance: autotrophy and heterotrophy. Plants are predominantly autotrophs, or "self-feeders," capable of producing their own food. They do this through a remarkable process called photosynthesis, converting light energy into chemical energy. This places them at the base of nearly every food web on Earth. Animals, on the other hand, are heterotrophs, meaning they must consume other organisms, whether plants or other animals, to obtain the complex organic molecules they need for energy and growth.

The Plant's Strategy: Harnessing the Sun

For most plants, the nutritional process is a highly efficient internal manufacturing operation. Using chlorophyll as a catalyst, they combine simple, inorganic raw materials to create their own food supply.

The inputs for plant nutrition include:

Sunlight: The primary energy source captured by chlorophyll.
Carbon Dioxide ($$CO_2$$): Absorbed from the atmosphere through tiny pores called stomata.
Water ($$H_2O$$): Absorbed from the soil through the roots.
Inorganic Minerals: Absorbed from the soil, including macronutrients like nitrogen, phosphorus, and potassium, and micronutrients such as iron and zinc.

The chemical energy produced from this process is stored primarily as carbohydrates, with glucose molecules stored as the larger polysaccharide, starch. Plants use this energy for their metabolic activities and growth, a process that is far less energy-intensive than that of mobile animals.

The Animal's Strategy: Consuming and Digesting

Animal nutrition, known as holozoic nutrition, involves a complex sequence of steps to break down and absorb food. This necessitates specialized anatomical structures for capturing and processing food, from the mouthparts of insects to the complex digestive systems of vertebrates.

The steps of animal nutrition include:

Ingestion: The process of taking food into the body, typically through a mouth.
Digestion: The mechanical and chemical breakdown of complex food molecules into simpler, absorbable units like amino acids, simple sugars, and fatty acids.
Absorption: The transport of these simple nutrients from the digestive tract into the bloodstream.
Assimilation: The utilization of absorbed nutrients by the body's cells for energy, growth, and repair.
Egestion: The elimination of undigested waste from the body.

Because animals must hunt, forage, or graze to acquire food, their energy demands are significantly higher than those of plants. They store excess glucose in the form of glycogen, a more readily accessible energy reserve than plant starch.

A Direct Comparison: Plant vs. Animal Nutrition


Feature	Plant Nutrition	Animal Nutrition
Mode	Autotrophic (mostly)	Heterotrophic
Energy Source	Sunlight (photosynthesis)	Chemical energy from consumed organic matter
Nutrient Source	Inorganic substances ($$CO_2$$, water, minerals)	Organic matter (plants, other animals)
Energy Production	Photosynthesis and cellular respiration	Cellular respiration only
Carbohydrate Storage	Starch	Glycogen
Key Nutrients	Nitrogen, phosphorus, potassium, etc.	Carbohydrates, proteins, fats, vitamins, and minerals
Vitamins Required?	No, they synthesize all necessary organic compounds	Yes, many vitamins must be obtained from diet
Digestive System?	No, nutrients are processed at the cellular level	Yes, specialized organs for digestion

Similarities and Interdependence

Despite their stark differences, plants and animals share some fundamental nutritional requirements and metabolic processes. Both require a constant supply of the four primary building-block elements: carbon, hydrogen, oxygen, and nitrogen. They both need water to facilitate metabolic reactions and require a range of essential minerals for various cellular functions. Furthermore, both organisms generate ATP, the universal energy currency of cells, through cellular respiration, although animals are entirely dependent on it for energy, whereas plants produce it via photosynthesis as well. The interdependence is also profound; the oxygen produced by plants is essential for animal respiration, and the carbon dioxide animals exhale is a key ingredient for plant photosynthesis, forming a symbiotic cycle of life. To learn more about this vital exchange, see the Georgia Institute of Technology's overview on nutritional needs and principles of nutrient transport.

Evolutionary and Ecological Significance

The contrasting nutritional strategies of plants and animals have shaped the course of evolution and the structure of ecosystems. The ability of plants to fix carbon from the atmosphere makes them the primary producers, fueling the entire food web. This sessile, self-sufficient lifestyle allows plants to exist without needing to expend energy on locomotion. In contrast, the heterotrophic nature of animals, combined with their higher energy needs, has driven the evolution of sophisticated behaviors for hunting, foraging, and migration. These differences in nutritional strategy are not just biological details but are the foundation for the entire complex, interconnected web of life on our planet.

Conclusion: Two Paths to Survival

In conclusion, the answer to how the nutrition in plants compare with the nutrition in animals is a tale of two distinct but complementary approaches. Plants build their own organic fuel from simple inorganic components using the power of the sun. Animals, by contrast, act as consumers, deriving their nutrition by ingesting and breaking down complex organic matter from other living things. While both kingdoms share basic requirements for building blocks and water, their modes of energy acquisition, storage, and processing define their ecological roles and have driven the incredible diversity of life we see today.

Frequently Asked Questions

The primary difference is their mode of nutrition: plants are autotrophs that create their own food using inorganic materials and sunlight, while animals are heterotrophs that must consume other organisms for organic nutrients.

No, animals do not perform photosynthesis. They rely solely on cellular respiration to break down the organic compounds they ingest to produce energy.

Animals need a digestive system to break down the complex organic molecules from the food they eat into simpler, absorbable nutrients. Plants, as autotrophs, synthesize their nutrients internally at the cellular level and do not require a digestive system.

Plants absorb essential inorganic minerals, like nitrogen, phosphorus, and potassium, from the soil through their root systems.

In plants, excess carbohydrate is stored as starch. In animals, it is stored as glycogen, primarily in the liver and muscles.

No, plants do not need to consume vitamins because they are capable of synthesizing all the organic compounds they require for their metabolic functions.

Plants are the primary producers, converting sunlight into chemical energy. Animals are consumers, relying on plants (or other animals) for this energy. This relationship forms the basis of the food chain and nutrient cycles.

Yes, there are exceptions. Some plants, like the Venus flytrap, are carnivorous and supplement their autotrophic nutrition with organic matter. Similarly, some animals, like corals, have symbiotic relationships with photosynthetic algae.