The Hunting Process of Carnivorous Plants
Venus flytraps（捕蠅草）, pitcher plants（豬籠草）, Drosera spatulata（小毛氈苔）, these noted carnivorous plants are famous to many people. However, have you ever wondered the evolutionary mechanism of these unusual plants and how they absorb the nutrient to maintain life? Million years ago, the carnivorous plants grew on the barren and slightly acidic wetland, where their habitat was lack of essential nutrients (nitrogen and phosphate fertilizer), and many plants were died of nutritional deficiency out of the leaching process, which means the extraction from substances in solid by liquid. Therefore, the carnivorous plants gradually developed a distinct method to adapt to this harsh living environment—in other words, they trapped insects and small animals as supplement for minerals and enzymes. These extraordinary creatures also play a complex and special role as both the secondary consumer and producer in the ecological system. Not only is the evolutionary process of carnivorous plants fascinating and surprising, but also their hunting process is a biological miracle worth our further understanding. There are three steps involved in the carnivorous plant’s curious hunting process: attracting insects, trapping prey with the distinctive organs, and secreting the digestive juice to take in the nutrients.
Pitcher plants（豬籠草）
Venus flytraps(捕蠅草)
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In the beginning, to attract insects, the carnivorous plants have developed different mechanisms by using special odor, colorful appearances, or nectary to entice insects. For example, the pitcher lid of Sarracenia（瓶子草） and pitcher plants can secrete the nectar gland, and the Venus flytraps may give off a particular odor to appeal to their quarries. However, these special odors vary from the floral scents that we are familiar with, like the fragrance of rose and lavender. Human beings are not able to smell the odor emitted by the carnivorous plants, and only the insects or small animals with the more sensitive olfactory sensation than a human can sense the sweet but deadly temptation from these predators. With the mechanisms to attract insects, the carnivorous plants only need to wait patiently without taking the initiative in trapping the prey.
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Afterward, they trap the prey like flying insects, ants, or spiders with their distinctive organs. Once an insect or animal approaches the trap, it may trigger the mechanosensor (the response to change in mechanical stimuli) on its surface.
Then, the carnivorousplants may shut down their trap immediately to avoid their prey from escaping. The most renowned instance is the trap of Venus flytraps, when the innocent victims come into the trap and touch the trigger hairs on its lobe, it may activate the hunting mechanism. In addition to traps, the carnivorous plants may also use their slippery surface to trap their prey. Take pitcher plants for example, as long as the insects are drawn by the nectar gland and step on the surface, they are very likely to fall into the pitcher body due to the slimy nectar. Thus, these special hunting organs are regarded as deadly weapons for helping them catch the prey effectively.
Drosera spatulata（小毛氈苔）
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Finally, to digest the prey, they secrete the digestive juice to help them take in the nutrients. According to Caroline Donnelly (2008), “The insects are intoxicated by this liquid, which contains bacteria and enzymes that will eventually dissolve their carcasses.” To be brief, these predators may secrete digestive juice to decompose the prey into minimal molecules, and then absorb useful nutrients for living. The time for the carnivorous plants to break down and take in the nutrients of the prey may be different from a few days to nearly one month, and it will take about one month for them to execute the next hunting. By digesting the nutrients, the carnivorous plants eventually break down the limit of their living condition to maintain life.
Sarracenia（瓶子草）
In conclusion, it is no exaggeration to say that both the evolutionary and hunting process of the carnivorous plants can be regarded as the biological wonder, and it shows us the resilience and amazement of life. Regardless of the severe living condition, the carnivorous plants develop a special hunting process—through different mechanisms to attract insects, special organs to trap their prey, and to secrete the digestive juice to conquer the handicap. According to the old saying: “It is not the strongest of the species that survives, nor the most intelligent that survives. It is the one that is most adaptable to change.” No wonder that nature always brings us many inspirations, and we can also learn from our best teacher, “nature”.
Resources
Donnelly, C. (2008) The Hunting Strategies of Carnivorous Plants
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