If you've seen the musical/movie "Little Shop of Horrors," you might have been left with a bad impression of what really is a neat plant. While Audrey, the mutant Flytrap in the movie, developed a taste for humans, the real plant prefers insects and arachnids like:
If other plants can thrive on gases in the air plus water from the soil, why do Venus Flytraps eat insects? Flytraps actually get a good deal of their sustenance like other plants do, through the process of photosynthesis. During photosynthesis, plants use the energy of the sun to drive a reaction that converts carbon dioxide and water to sugar and oxygen. The sugar produced is then converted to energy in the form of ATP, through the same processes used by our bodies to process carbohydrates.
However, in addition to synthesizing glucose, plants also need to make amino acids, vitamins and other cellular components to survive. To accomplish this, plants needs additional nutrients like:
- nitrogen - to make amino acids, nucleic acids, proteins
- phosphorus - as part of the energy-carrying ATP molecule
- magnesium - as a co-factor that helps many enzymes function
- sulfur - to make some amino acids
- calcium - as an enzyme co-factor and to make plant cell walls
- potassium - to regulate water movement in and out of the plant
In the bogs favored by Venus Flytraps, the soil is acidic, and minerals and other nutrients are scarce. Most plants can't survive in this environment because they cannot make enough of the building blocks necessary for growth. The Venus Flytrap has evolved the ability to thrive in this unique ecological niche by finding an alternate means of getting key nutrients like nitrogen. Living creatures like insects provide a good source of the nutrients missing from the soil, and they also contain additional energy-laden carbohydrates.