Sunday, 5 June 2011

My First Plant - The Venus Fly Trap

Against the superstition of my parents, I got myself a venus fly trap from Takashimaya Cold Storage two days ago! (I used to own a typical female tree lizard when I was 11 years old and had to release it into the wild when my mum became pregnant with my brother because it was 'inauspicious'.) Why only now? Because I had never seen it sold anywhere else around Singapore before. This is officially the first plant I have ever owned, and as an evolution and natural design junkie this is probably THE plant to own.

Costing a silly $28.50, the venus fly trap has always been a childhood fascination for the simple fact that it is a very different kind of plant, which makes it cool. It doesn't just sit around, immobile, settling for bland water. It lures, seduces, attracts and kills, which means it has personal tastes and an appetite. Awesome.

You can read up all about it at HowStuffWorks, but in a nutshell the venus fly trap is an ode to evolution. It is native to the coast of North and South Carolina, because of the abundance of wetlands and humidity. Most plants can't survive in these areas because the soil is acidic, and minerals and other nutrients (which are necessary building blocks for plant growth) are scarce. The venus fly trap has evolved the ability to thrive by finding an alternate means of getting key nutrients such as nitrogen via living creatures like insects which also contain additional energy-laden carbohydrates.

As a result of trying to own a venus fly trap outside of its natural wild habitat, my venus fly trap is quite a baby for the care it requires. In order to mimic its natural conditions, distilled or rain water is needed as it cannot survive off tap water that is treated with unnatural chemicals. The dissolved solids in tap water - sodium, calcium, alkaline salts, sulphur, chlorine and magnesium - are detrimental to its health. My brother and I had quite a bit of fun trying to distill our own pure water, using a trick I learnt from the survival tip on how to extract drinking water from sea water (click here for another variant of this trick that can be done at home). Other simple, practical and readily available sources of pure distilled water include condensed water from air conditioners and car battery water.

The venus fly trap may survive without eating prey, but it certainly flourishes when it has nutritious food sources. So, if the venus fly trap is not located in the wild, feeding must be manually done. Good food includes flies, spiders, crickets, slugs and caterpillars within the length of 1/3 an inch (one inch being the size of an average trap). 2-3 bugs a month constitutes a healthy diet.

In the absence of a brain and animal perception, the venus fly trap accomplishes its task of capturing prey through specialized leaves that are both mouth and stomach in one. The leaves forming the trap secrete a sweet nectar that attract insects in search of food. It's a very interesting process but gets a little bit scientifically technical from here on, so a copy and paste from the HowStuffWorks page will have to do:

"When an insect enters the trap, it is likely to run into one of six, short, stiff hairs on the trap's surface. These are called trigger hairs, and they serve as a primitive motion detector for the plant. If two of these hairs are brushed in close succession, or one hair is touched twice, the leaves close down upon the offending insect within half a second.

What causes the leaves to squeeze shut? Nobody knows exactly how the sequential, mechanical stimulation of the trigger hairs translates into closing the trap. The prevailing hypothesis of the day is that:

1. Cells in an inner layer of the leaf are very compressed. This creates tension in the plant tissue that holds the trap open.
2. Mechanical movement of the trigger hairs puts into motion ATP-driven changes in water pressure within these cells.
3. The cells are driven to expand by the increasing water pressure, and the trap closes as the plant tissue relaxes."

The plant is thus capable of "distinguishing" between prey and inedible debris according to whether more than one trigger hair is touched. The food selection process may not be perfect (because real food in the form of flies and spiders may be crawling all around the plant, but the fly trap may be closed shut over something useless such as a leaf or twig), but this simple strategy has allowed it to do without muscles or a brain, which are very costly organs and tissues to sustain.

The digesting process is also very remarkable. Once the trap fully closes, the leaves form an airtight seal through long hair-like projections known as cilia so that digestive fluids and insect parts are kept inside the trap and bacteria and molds cannot enter. The finger-like cilia create the awesome impression of spiny teeth that has captured the imagination of monster-plant story spinners, but they are really only used to keep the trap latched shut.

Sometimes, a trap does not close shut and as a result may suffer from a bacterial infection, rot and fall away. The venus fly trap can tolerate losing traps because it can eventually sprout new ones. However, beyond this, the venus fly trap is also capable of losing traps "strategically" through "planned obsolescence", and this is one of its most amazing characteristics to me. When a trap runs its course of about 10 to 12 closures, it loses the ability to capture anything. The leaves of a trap remain spread wide open and it then devotes all its energy to the process of photosynthesis for the remainder of its life span, usually around 2 to 3 months. This former trap thus no longer goes through the ritual of attracting insects and eating them. In a purely evolutionary sense, this is somewhat similar to how menopausal mammals contribute to their social groups. This way, if a trap is repeatedly stimulated by inedible objects either because it is incompetent or poorly located, the rest of the plant can recoup some of the energy and ATP lost on its inefficient trap and make it focus instead solely on photosynthesis.

Once the insect is firmly gripped by the trap, a process of digestion begins. The trap secretes acidic digestive juices that dissolve the soft tissues and cell membranes of the food, serve as an antiseptic to kill bacteria and enzymatically digest DNA, amino acids and other cellular molecules into small pieces that can be eventually ingested by the plant. The process continues until only the hard exoskeleton of the prey remains. Once the prey's nutrients are depleted, the plant reabsorbs the digestive fluid. This serves as a signal to reopen the trap, and the prey's remains are left behind. In natural conditions, wind and rain water helps to remove the remains but, indoors, I'll have to manually remove them for my plant.

As this is my maiden attempt, I'm not certain of my ability to keep my venus fly trap alive. But I'll give it a shot. Most plants hardly pique my interest but this high-maintenance creature certainly is a beauty!


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