Can Carnivorous Plants Eat Humans?

Anyone who has seen the 1986 musical comedy Little Shop of Horrors knows the character Audrey II, a giant, blood-thirsty plant resembling a Venus flytrap, capable of jaw-like movement and the sudden snapping shut of its carnivorous appendages.

Anyone who has seen the 1986 musical comedy Little Shop of Horrors is familiar with the character of Audrey 2. Audrey 2 is a giant, blood-sucking plant with a Venus flytrap-like appearance that even mimics the jaw-like movement and sudden closing of the predatory limbs of real carnivorous plants. The difference is that the Venus flytrap hunts insects, but Audrey 2 feeds on humans.

Fortunately, plants that eat humans only exist in fiction. Kenny Coogan, owner of Kenny Coogan Carnivorous Plant Nursery in North Carolina's Piedmont Triad, confirms this.

However, plants that trap and digest insects and sometimes small rodents are quite real and very diverse. Popular Science magazine interviewed Kogan to investigate why some plants become carnivorous and how they differ from plants that absorb their nutrients directly from the soil. He was also asked about the characteristics that make these plants dangerous for birds and other small animals.

Carnivorous plants are flowering plants that provide the nutrients they need by absorbing, trapping and digesting animals. These plants are both autotrophic, that is, they make their food using light energy or chemical energy, and they are considered heterotrophic; Because they also need to hunt animals to survive.

Carnivorous plants carry out photosynthesis. Using sunlight, they convert carbon dioxide and water into sugar, and they also get some of the minerals and nutrients they need from insects and creatures they hunt.

These plants are found in almost all continents of the world, except Antarctica. Their usual habitat is sunny areas with very poor, acidic soil lacking sufficient nutrients. For example, the swamps, marshes, and wetlands of North Carolina and Florida provide the perfect conditions for the growth of these adapted plants, thanks to their special combination of sunlight and moist environments.

The Venus flytrap, native to North and South Carolina in the United States, is one of the well-known examples of this group. Tracy's sundew is another example of these plants with its long, thread-like leaves that grow in a spiral. This species is often found alongside carnivorous pitcher plants in the Florida Panhandle.

Coogan said about the reason for the evolution of this feature:

Carnivory is primarily an adaptation that helps plants meet their needs in environments with few nutrients. These plants obtain nitrogen, phosphorus and other essential organic substances from insects; Materials for which it is not possible to absorb a sufficient amount of them through the soil.

Of course, not every plant that grows in wetlands with poor soil is carnivorous. Wiregrass, abundant in the southeastern United States, is an example of these plants. Coogan explained:

This plant has a very wide and powerful root system that has established a symbiotic and long-term relationship with mycorrhizal fungi. These fungi attach to the roots of wire grass and help it obtain nutrients from the area's sandy and infertile soils.

He further pointed out the difference in the adaptation paths of plants and said:

In each ecosystem, there is a certain number of habitats for species. Therefore, some plants have adopted the carnivorous path and others have used different strategies to survive.

How did carnivorous plants evolve?

About 800 to 860 species of carnivorous plants have been identified worldwide, and scientists continue to discover new species. During the more than 140 million years since the emergence of flowering plants, the trait of carnivory has evolved independently at least 12 times in different phyla.

This feature has not been transferred from a common carnivorous ancestor to all modern plants. Instead, specialized leaf structures, including sticky traps, sudden traps, and pit traps for hunting insects, have evolved and diversified in more recent times. Most of these changes date back to the period between 8 and 72 million years ago.

Carnivorous plants are a well-known example of convergent evolution. This term refers to the process by which unrelated biological groups independently acquire similar characteristics to adapt to the same environmental conditions. In the case of these plants, sunny, humid and nutrient-poor environments have played an important role in the formation of this adaptation.

For example, pitcher plants have many species whose hollow, pitcher-like leaves act as traps to trap insects. Kogan said about this:

There are several species of potted plants that are not closely related to each other. Some of them grow close to the ground in Australia and are evolutionarily closer to roses, beans and broccoli. Asian species hang from tropical vines, and North American pitcher plants have an upright, trumpet-like structure. Despite the stark difference in DNA, all these plants independently developed similar tube-shaped pit traps to catch and digest insects.

Convergent evolution has also caused plants such as Venus flytrap, sundew, and pitcher plants to convert ancient genes associated with self-defense into tools for digesting prey. Non-carnivorous plants have long used enzymes called chitinase to fight fungal infections, but carnivorous plants have a different use for these enzymes.

With the help of chitinase, they break down the hard, chitin-rich exoskeleton of trapped insects. As a result, it becomes possible for them to absorb vital nutrients such as nitrogen and phosphorus. In this way, the enzymes that initially had a defensive and protective role have become active tools for hunting and digestion.

Are carnivorous plants dangerous to larger creatures?

Kenny Coogan said in response to this question:

In my opinion, the answer is no. Almost all carnivorous plants feed exclusively on small insects such as flies, mosquitoes and spiders.

However, some species, including giant pitcher plants, grow so large that they can trap and digest small animals such as mice and insectivores. However, the relationship of these plants with some animals is more of a symbiotic nature; It means that both parties benefit from this relationship.

Some large species of pitcher plants produce a sweet, fragrant nectar on the underside of their cap that attracts small mammals. Kogan explained how these animals interact with the plant:

These mammals sit on the lid of the jar to drink the secretions of the plant, which is a thick nectar-like substance.

These animals often leave their excrement in the jar while feeding. The plant also directly absorbs the abundant nitrogen and phosphorus in these wastes. As a result, both the animal feeds on the nectar and the plant gets the nutrients it needs.

This example is one of the many cases of symbiosis among carnivorous plants. Of course, if a small animal accidentally falls into the jar, the plant can digest it using its digestive enzymes and acids.

Some of the most amazing carnivorous plants

Kogan's favorite carnivorous plants include a wide variety; From the small and semi-aquatic species of the genelisia genus, which are known as winding plants, to the bubble plants, whose small, bag-like traps catch small aquatic creatures, and whose flowers sometimes resemble orchids.

Coogan said about the variety of bubble plants:

There are more than 200 species of these plants that live in three different habitats. Some are completely aquatic and float on water. Another group grows in very wet soils and the third group lives on trees and among mosses.

All of these species use very fast suction traps that draw prey in by creating a vacuum.

In fact, bubble plants are among the fastest predatory plants in the world and can trap their prey in less than a millisecond. Coogan said about the reason for his interest in these plants:

The main reason for my interest in them is their power of reproduction and abundant flowering; So that they produce many flowers at the same time.

Korean herbs are another popular option. Coogan particularly admires the Mexican species of these plants of the Pingicula genus and said:

The reason they are so popular is that they are great houseplants. They look like succulents, but their sticky leaves attract fruit flies and fungus gnats. For this reason, they can be used as a natural method of pest control in the home.

The largest carnivorous plant in the world in terms of trap volume is the giant mountain pitcher plant. This plant is native to Malaysian Borneo and its huge, jar-like traps can be up to 41 cm high and 20 cm wide.

Sometimes small reptiles such as lizards, frogs and birds get caught in these traps and are exposed to the acids and digestive enzymes of the plant, but most of the animals in the area are safe from such danger.