Why are some plants insectivorous, or carnivorous?

You perhaps are very familiar with the game Plants vs. Zombies, but if there will be a game about this thing, it would be Plants vs. Insects. Let’s find out why some plants eat insects and why they are carnivorous.

Just like humans, plants have basic needs to survive and grow. Sunlight, water, and air constitute the primary source of the diet of vegetation. Using the sunlight’s energy, the plants convert them into carbohydrates (starch and glucose), protein, and fat through the chemical process known as photosynthesis.

In other words, the plants convert the sunlight, water, and the air into chemical energy. The process occurs directly at the level of cells, the basic biological units, without a digestive system of any kind.

However, these elements are not enough and do not constitute the vegetation’s complete ‘diet.’ Plants also need minerals like nitrogen, calcium, phosphate, and iron for nourishment. Nitrogen is necessary for the manufacturing of protein and calcium for the strong cell membrane. Likewise, phosphates build-up nucleic acid, whereas iron is essential for chlorophyll or the green pigments in the leaves that absorb sunlight for photosynthesis. The plants absorb these minerals from the soil – and ideally, they must pre-exist in the soil in optimum quantities. The vegetation can’t flourish in the soil lacking these nutrients.

But not all plant species have the same needs as mentioned. The insect-eating plants, carnivorous plants, or some call it insectivorous plants are unique exceptions.

Millions of years ago, plants have made a remarkable adaptation due to the low nutrition environment. Wherever the soil does not provide sufficient nitrogen and other minerals they need to live, nutrients they devour insects like ants, butterflies, flies, grasshoppers, moths, and even small frogs and lizards!

What are insectivorous plants?

Venus flytrap with a trapped fly

Carnivorous plants tend to grow in places with acidic soil, usually poor in crucial nutrients like nitrogen, potassium, and phosphorus. There are several insect-munching plant species, including snap traps, bladder traps, pitfall traps, and paper traps.

1. Snap traps

With Venus flytrap as the most known of all, snap traps are among the fascinating carnivorous plants. Darwin was perhaps mesmerized by its beauty that he described it as one of the most wonderful plants in the world. Venus flytrap is also known as Dionaea Muscipula and is found only in the coastal bogs and swamps of North and South Carolina, USA.

The second one kind of a snap trap is believed to be a close descendent of this Venus flytrap known as the waterwheel plant, Aldrovanda vesiculosa. As its name suggests, this plant lives underwater in shallow acidic waters of wetlands in central Europe, East Asia, Africa, and Australia.

2. Pitfall traps

The plants have a very attractive scent and a flower-like pattern – too alluring for the insects that they cannot resist to come closer and be tempted to suck nectar bribes. However, these plants have a substance called coniine in its nectar – a powerful narcotic to insects. When the coniine takes effect, the insect will fall down the funnel where it drowns into a pool of water stored within the pitcher containing enzymes and bacteria that will break down into particles small enough that the plant’s leaves can consume. This type of ‘water body’ is called a Phytotelma.

Heliamphora probably has the simplest pitcher plants. In this genus, the traps are from a simple rolled leaf whose margins have sealed together. These plants are found in the regions of high rainfall in South America, such as Mount Roraima.

3. Bladder traps

Bladderwort plants feed on small aquatic organisms like larvae, copepods, and water fleas. These plants lack roots but have a horizontal floating stem bearing simple or divided leaves. Along the stem are the small carnivorous bladders range from dark to transparent in color. It has bisexual and bilaterally symmetrical flowers, with two sepals, five fused petals, two stamens, and a superior ovary (i.e., positioned above the attachment point of the other flower parts) composed of two ovule-bearing segments (carpels). The mature plants produce many seeds.

4. Paper traps

Paper traps ensnare their victims with sticky mucus that also acts as an attractant. Butterworts (Pinguicula spp.) are one of the species. There are about 80 species of this genus and with discoveries still being made in recent years.

With its scent and sticky nectars, small insects like fruit flies and gnats are ensnared on short stalks attached to the leaf surface. Once the insect lands, it cannot anymore free itself and eventually be digested on the leaf surface by a mix of digestive enzymes and acids secreted by the plant, with only their exoskeleton remaining as evidence of their demise.

Most of these plants grow in native habitats throughout the northern hemisphere and southward into Central and South America. They are also abundant in Mexico.


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