How do Carnivorous Plants Kill?

Karina G's picture

 

How Do Carnivorous Plants Kill?
 
            The simplest definition of a plant says that a plant is a living organism that produces its own food/nutrients from inorganic matter through the process of photosynthesis. However, carnivorous plants get most of their nutrients from the consumption of other living organism such as insects, not from inorganic material. These living organisms do not comply with the definition of a plant. Nonthelesss to define “plant” there are other characteristics that biologist have considered. The fact that a plant consumes other living organisms makes carnivorous plants unique. Not only does it feed on creatures but the mechanisms use to lure and kill their prey is fascinating. Such features have caught the attention of people. Perhaps mass media has helped increase the fascination for these plants. Horror films portrayed a carnivorous plant as one that could eat humans. Such hyperbole contributed to the allurement of these plants and created the misconception that these plants are blood thirsty. While I know that carnivorous plants do not eat humans I am too fascinated and puzzled as to how they function. I too wonder what is the largest animal they can capture to consume. And most importantly how do they kill.
The International Carnivorous Plant Society website describes a carnivorous plant as one that has the following three attributes. The first characteristic is that the plant must have features that help capture the prey. Second, it must have a way to digest the prey. The plant may produce digestive enzymes, or rely on bacteria to break down the prey. Third feature is that it must have an effective way to absorb the nutrients and benefit from them. After scrutinizing several definitions it can be said that a carnivorous plant is a plant that derives some or most of their nutrients from consuming animals, generally arthropods (invertebrates that have an exoskeleton) and insects. We must add to this definition that these plants have the tendency to grow in places where the soil is thin or poor in nutrients, specifically nitrogen. This is crucial for understanding why these plants have adopted a new way for getting the nutrients they need. Charles Darwin himself was fascinated by these specimens. Carnivorous plants certainly follow under Darwin’s theory of natural selection.
There are hundreds of different kinds of carnivorous plants. Biologist have categorized in different ways, however the most useful for our purposes is labeling them by their trapping methods. There are five basic trapping mechanisms: flypaper traps, pitfall traps, snap traps, bladder traps and lobster-pot traps. (Wikipedia)The first uses a sticky mucilage or glue secreted by glands studded on the leaves. Pitfall traps capture their prey in a rolled leaf which has digestive enzymes or bacteria. Snap traps employ rapid leaf movements. Meanwhile bladder traps suck in their prey into the bladder by generating a sort of vacuum. Like many these species has hair that triggers the vacuum. The lobster trap has inward pointing hair on their leaves. The hairs allows the prey to move only in a particular direction, that being down into a stomach where is digested. It must be said that some of these carnivorous plants can be active or passive.
Needless to say that there is a set interest for those who are active. The most famous is a snap trap called Venus Flytraps or in Latin Dionaea. Darwin studied Dionaea because of the sensitivity and speed of the plant’s leaves. “Recent molecular work confirms Darwin’s conjecture... that snap- traps evolved from a ‘flypaper’ trap. Transitions include tentacles being modified into trigger hairs and marginal ‘teeth’, the loss of sticky tentacles …” (Gibson & Waller 575) The evolution from flypaper to snap trap benefited the plant because it allows it to capture larger prey, bringing in a rewarding variety of nutrients. Depending on the size of the plant they can trap and digest a mouse. Moreover, Venus flytrap secretes sweet nectar that attracts insects looking for food. Although these lack of sticky hair instead they have ‘trigger hairs’. The trap doesn’t close just because an insect is there but because it touches one or more of the ‘trigger hairs’. “If a single hair is touched twice or two separate hairs are stimulated within 1-20 s, the trap snaps closed in 0.3 s” (Gibson & Waller 578). When the trap closes the teeth on the margins of the leaves interlock to prevent prey to escape, however small prey might get away. To make matters worst for the insect, the plant responds to crawling like movement and begins to secrete digestive enzymes. This way Venus flytrap makes sure that it wasn’t a false alarm or that the prey already escaped. Gives chills to know how sage this plant is!
There is no doubt about the complexity of carnivorous plants and the curiosity they arouse on people. Although the evolution of these species wasn’t explored on this paper it is imperative to mention that evolution and adaptation to the environment makes possible their existence.  Their evolution has also contributed to the variety and most complex kinds of carnivorous plants. Reading about carnivorous plants also helps us appreciate the sagacity and tenacity of nature. Perhaps what causes much interest on the Venus flytrap is the violence with which captures prey. However, we cannot forget that there are many different ways a carnivorous plant kills. Some lured insects with colors and nectars just to suck you in or kill you slowly with bacteria. The most beautiful and tranquil plant can be lethal. That is how nature works.
 
 
 
References
 
·         Gibson, Thomas & Waller, Donald. “Evolving Darwin’s ‘most wonderful’ plant: ecological steps to a snap trap” New Phytologist,  
2002009, Volume 183: 575-587.
 
·         Rice, Barry. The International Carnivorous Plant Society. 2009. Web <http://www.sarracenia.com/faq.html> 27 Sep, 2009
 
 
·         “Carnivorous Plant” Wikipedia. 2009. Web. <http://en.wikipedia.org/wiki/Carnivorous_plant> 28 Sep, 2009
 

 

Comments

Types of plants's picture

Great refrence article!

I was doing researches on various types of plants for my new project and stumbled upon this article. I am inspired to write about carnivorous plants and do some more through research on it. Thanks.

Paul Grobstein's picture

"There is no doubt about the

"There is no doubt about the complexity of carnivorous plants and the curiosity they arouse on people."

I wonder though WHY they arouse such curiosity in people?  Perhaps relevant: Is pain a pleasure and why? 

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