Fungi are classified as heterotrophs because, like animals, they cannot produce their own food. Instead, they rely on organic matter from their environment to obtain the nutrients they need for survival. This process is known as heterotrophy.
Fungi absorb nutrients from their surroundings through a process called extracellular digestion. They secrete enzymes that break down complex organic materials into simpler compounds, which they then absorb. This method of obtaining nutrients is similar to how animals digest food internally.
Unlike plants, which are autotrophs and can produce their own food through photosynthesis, fungi lack chlorophyll and cannot perform photosynthesis. This fundamental difference places fungi in the same nutritional category as animals, making them heterotrophs.
In summary, fungi are classified as heterotrophs because they depend on external sources of organic matter for their nutrition, much like animals do.