Carnivorous plants are evolutionary wonders. They blur the lines between the plant and animal kingdoms with their locomotive abilities and non-photosynthetic diet. Some wonder if they have evolved so much as to be capable of feeling pain.
So, do carnivorous plants feel pain? Carnivorous plants do not feel pain, as they do not have pain receptors, but they are able to detect when physical damage is being done to them.
Some plants can react to physical touch, in a manner analogous to that of muscle movement in vertebrates. Species such as Mimosa pudica (shameplant) and Dionaea muscipula (Venus flytrap) have an organ called the pulvinus, which works along with the motor cells, flexors, and extensors to move the plant.
Although these and similar species are evolved in a way that many other plants are not, they are still distinguished from vertebrates in the sense that they do not have the cognitive ability to feel pain or suffer.
Do Plants Have Pain Receptors?
According to Daniel Chamovitz, Dean of Life Sciences at Tel Aviv University in Israel and author of What a Plant Knows, plants do not have pain receptors, but instead, are informed by mechanoreceptors. These are a type of pressure-sensitive receptor.
The mechanoreceptor informs the plant of physical interactions ranging from direct touch to actions which cause any amount of friction against the plant. The plant then reacts with a given movement, which is accomplished by the motor cells manipulating turgor pressure within the cells.
For example, the Venus flytrap reacts to mechano-sensory information from its sensory hairs. When an insect or small animal, such as a frog, touches at least three of these hairs in succession and within 20 seconds of each other, the “trap” closes and holds the animal in place while the plant digests it.
The shameplant, when touched on the underside of its leaves, where its sensory hairs are located, folds either side of its leaf up against the other.
What Is the Pain Receptor That Allows Animals to Feel Pain?
The pain receptor that allows animals to feel pain is called the nociceptor. It alerts the organism to sensations that may be indicative of a threat.
Perhaps the fact that vertebrates evolved methods of escaping potential threats, a la “Fight or Flight,” whereas plants do not have such a mechanism and are capable of regeneration, is a reason why there was no evolutionary need for plants to develop similar pain receptors.
Are Carnivorous Plants Conscious?
Plants do not have a nervous system of any kind but instead are governed by electrical impulses, much like the synapses that allow our brains to oversee the functioning of our bodies. According to current scientific understanding, this lack of a nervous system and inability to feel pain point to a consequential inability to be sentient.
Sure, the Venus flytrap is able to keep track of how many times its sensory hairs have been touched in a period of 20 seconds – even Dr. Chamovitz refers to this mechanism as a sort of “memory.” Still, this is not necessarily indicative of cognition.
Interestingly though, the ability to communicate between distinct plants has been observed in numerous species. A popular example of this is the smell of freshly-cut grass: the nostalgic smell that humans enjoy is, in fact, a distress signal expressed by the grass when cut.
This signal is intended to serve as a warning to nearby plants that danger is approaching, and, depending on the species, is accompanied by even more chemical defenses and communications. In this way, scientists have found that plants are capable of communicating; however, evidence for sentience in plant species is yet to be found.
The Plant That Learned to Count
Despite an absence of evidence regarding sentience in carnivorous plants, the Venus flytrap continues to defy the supposed rules of nature in its ability not only for locomotion and memory but also “counting.”
This is directly related to the “memory” function regarding the number of times the flytrap’s sensory hairs are touched. Professor Rainer Hedrich of the Universitӓt Würzburg explained that the plant is not only able to keep track of the number of contacts with sensory hairs, and with this information, it can determine the nutritional content of captured prey.
The Venus flytrap’s ability to essentially make decisions based on a superficial cost-benefit analysis of potential nutrition to be gained by consumption of a particular prey item pushes the boundaries of what we call sentience versus non-sentience.
The Debate Lives On
Although it is increasingly evident that plants do not display any level of sentience, there are still those who believe that they are, in some ways, conscious and because of that, deserve rights just as animals do.
Neurobiologist, Stefano Mancuso, and journalist, Alessandro Viola collaborated to argue in favor of plant sentience, intelligence, and legal rights in their book Brilliant Green: the Surprising History and Science of Plant Intelligence.
Mancuso and Viola discuss many schools of thought on the existence of plants: whether they exhibit social behaviours, whether they exercise intelligence, and more. They explain their belief that plants are not seen as sentient is due largely to anthropomorphism and speciesism, influencing humankind to continually underestimate the evolutionary capacity of the plant kingdom.
Although, in general, it is agreed upon throughout the scientific community that plants’ abilities to communicate and process information as previously described are not indicative of consciousness, Mancuso, and Viola, on the other hand, find this to be directly illustrative of plant awareness.
What this calls attention to is the idea that “sentience,” “cognition,” and “consciousness” are probably not notions that are officially or formally defined, but that are highly subjective and dependent on the individual discussing the topic.
Many who believe that plants are sentient have urged environmentalists and nature advocates to demand plants’ rights, muddying the waters of the ideology behind veganism and vegetarianism.
Though Plants Can’t Feel Pain, They Can Still Be Harmed
A major part of the attraction that drives people to purchase carnivorous plants is the locomotive ability that comes with them. In the case of the Venus flytrap, if the plant is not being purchased to rid the house of a fly problem, it’s often because of the temptation to play with the specialized leaves, the plant’s “traps.”
Despite how fun it may be to stick your finger in and out of the trap, it is actually not good for your plant. It does not technically cause any damage to the plant or cause any known type of pain, however, it does drain the plant of energy reserves for locomotion.
Many carnivorous plants that are native to North America originate from environments that are high in moisture: swamps, bogs, wetlands, etc. In consideration of this, know that your plant is already having to acclimate to whatever artificial environment you’ve created for it. Additionally, chances are your home does not offer nearly the same amount of insect life as a swamp.
Naturally, the Venus flytrap’s traps are only designed to open and close about three to four times in their lifespan before they shrivel up and drop off of the plant. Forcing it to open and close is detrimental to its health, as you are accelerating the deterioration of the trap and ultimately removing a tool integral to the plant’s ability to consume nutrients.
It can be said that you’re not technically causing any harm by playing with your plant, but, by doing this you are indeed hurting its health and longevity.