Venus flytraps are perhaps one of the world’s most widely-recognized carnivorous plants, with its snap trap being one of its most distinguishable characteristics. At first glance, a Venus flytrap’s aggressive ‘tooth’-lined jaw might appear somewhat intimidating, but that hasn’t stopped researchers from intensively studying the plant to better understand its particularly unique story.
Image Credit: Pixabay
While the Venus flytrap’s snap trap looks a lot to us like a mouth with teeth, it’s anything but; instead, it’s more like a spring-loaded trap that transforms into a ‘cage’ after responding to stimuli, such as when an unsuspecting insect contacts the surface. Moreover, those aren’t teeth lining the snap trap – they’re marginal spikes, and they help to trap any prey present inside of the trap when it closes.
Scientists have long wondered just how critical marginal spikes are to the Venus flytrap’s prey-catching success, but the answer was never clear. To that end, a team of researchers removed the marginal spikes from a test group of 34 Venus flytraps such that they could gauge the success of those plants in trapping prey of different sizes. Their findings have been published in the journal American Naturalist.
At first, the researchers spent about a week collecting data in a controlled laboratory setting, but they later moved to a ‘semi-natural’ environment in the North Carolina Botanical Garden to see if their results would be the same. Throughout the testing, the researchers recorded details concerning the Venus flytraps themselves and the prey they captured in an attempt to discern any significant patterns.
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Perhaps unsurprisingly, the data showed that the removal of the Venus flytrap’s marginal spikes seemed to impact the plant’s prey-capturing success, but this finding varied based on the prey’s physical size. Astonishingly, the removal of the marginal spikes made the test group up to 90% less effective at trapping moderate-sized crickets, but there was no discernible difference in the capture success rate of larger prey.
In the controlled laboratory setting, the Venus flytraps were 16.5% successful in capturing their prey with their marginal spikes and 5.8% successful with them. In the semi-natural setting, however, the Venus flytraps were 13.3% successful in catching their prey with their marginal spikes and 9.2% without them. The trends were somewhat parallel despite the apparent differences in the plants’ surroundings during both testing phases.
The findings indicate that the marginal spikes are essential for the successful capture of small and moderate-sized prey because they act much like the bars of a jail cell, preventing smaller prey from escaping the snap trap. Larger prey, on the other hand, is often strong enough to pry their way out of a Venus flytrap’s snap trap, often using the marginal spikes as leverage.
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As it would seem, marginal spikes only improve the Venus flytrap’s prey capture success rate, and don’t hinder it. With that in mind, it’s no wonder that the plants’ snap traps haven’t evolved much over the years – after all, why fix what isn’t broken?
Source: Phys.org, The American Naturalist