The Hunting Cycle of the Venus Flytrap

This is a review of the Venus flytrap research article:  “Complete hunting cycle of Dionaea muscipula: Consecutive steps and their electrical properties” by Volkov, et al., published in the Journal of Plant Physiology, 2011.

I found a couple of interesting ideas in this research.  The first of which is the authors’ description of the stages of trap closing and opening on a Venus flytrap.  This paper describes five stages of the trap closing and opening cycle.

1) Open

2) Closed

3) Locked

4) Constriction/Digestion

5) Semi-open

1) Open

When the trap has captured no prey, stage 4 does not occur.  What may be new to a lot of readers is that they describe two stages of closing before the sealed digestion stage. The article’s authors support this distinction with measurements.  many flytrap owners have probably observed that immediately after closing, the trap does, indeed, shut more and more before the edges seal together.  It is this slow tightening of the cilia (teeth) that they describe as ‘locked.’

Much like this locked stage of closing, the authors also described another stage of opening which they call semi-open.  They say that the trap will open to the semi-open stage first, then take another day to return to the fully open position.  This leads us to the second interesting idea in this article.

The authors point out that much of the energy used for closing of a trap is stored as potential energy in the two sides of the trap. This happens because the trap is open so far that the sides are even turned slightly inside out, effectively spring-loading them.  So when a trap re-opens, first it opens to the semi-open state, then takes some additional time to reset to the fully open, spring-loaded state.  Interestingly, the authors point out that a trap that is not fully open will close very slowly.  I’m sure many a flytrap owner has seen this kind slow closing on occasion, though may not have paid it much attention.  It makes sense that the traps cannot close quickly until they are fully open and re-loaded with potential energy.

Many readers know that Venus flytrap movement is powered by water being pumped into and out of cells (an osmotic motor).  This is true.  This article does not suggest otherwise.  They are simply pointing out that the wide opening of a trap (still water-driven) sets up an additional spring-loaded situation.

Most of the this article was an investigation into electrical stimulation of traps and measurements of the effects.  It produced much technical data that would be of no practical use to most of our audience here.


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