Carnivorous Plants


Carnivorous plants
Carnivorous plants are plants that obtain some or most of their nutrients from trapping and digesting animals or protozoans, mostly insects and arthropods. Since most of the carnivorous plants prey on insects, they are also refered to as ‘insectivorous plants’. These plants are usually found in soils which are deficient in Nitrogen. Many of the plants derive Nitrogen from the soil through their roots but carnivorous plants obtain it from their prey.
The leaves of the carnivorous plants are modified to trap the prey. Once trapped, the plants release the digestive juices to dissolve it and finally absorb the nutrients. Most carnivorous plants make their own digestive enzymes but some depend on bacteria to produce these enzymes. Just like common plants which adapt various strategies to attract pollinators for pollination, carnivorous plants developed several techniques to attract their prey. Some carnivorous plants produce sweet scent while some are brightly colored and some have parts that are sticky or slippery. Some plants are designed in a way that makes it hard for prey to escape.
There are five basic trapping mechanisms found in carnivorous plants.
Pitfall Trap
The simplest trapping mechanism in carnivorous plants is Pitfall. Here the leaves are highly modified (rolled) to form a bucket like receptacle. The pitcher has downward-pointing hairs on the inner slippery walls that prevents the insect from crawling out. The insect slips and drowns into the pool of digestive enzymes at the bottom.
Examples : Darlingtonia, Sarracenia, Nepenthes etc.
Flypaper Traps
In this type of carnivorous plants the leaves are covered with mucilage-secreting glands. These glands can be short, long or mobile and secrete sticky fluid that resemble water droplets. The colorful foliage and the shiny fluid attracts the insects towards it. When they come in contact with the leaves, the mucilage adheres it, thus preventing the prey’s escape. In many species, the sticky stalks can bend towards the prey, thereby suffocating it to death. The leaf blades can fold and curl, helping in absorbtion of nutrients by the specialized glands present on the leaf.
Examples : Drosera, Pinguicula
Snap Traps
These carnivorous plants trap the prey with rapid leaf movements. The leaf blade evolved with a fold in the middle and trapping teeth around the edges. It also bears trigger hairs and digestive glands on the surface. When the leaf is triggered by an insect, the blade closes along the midrib getting the two halfs together. Simultaneously the hairs around the edge of the leaf blade becomes interlocked thus trapping the insect. The hairs are triggered only when multiple touches occur successively. The prey is then broken down and digested.
Examples : Dionaea muscipula, Aldrovanda
Bladder Traps
This type of trap is seen Bladderworths. These are the type of carnivorous plants which are aquatic, terrestrial or epiphytic. Even though they thrive in different habitat, they all have bladder-like organs along the root system which are designed to capture and digest small invertebrates. The bladder traps also called suction traps are highly modified leaves in the shape of a bladder with a hinged door (trap door) lined with trigger hairs. The bladder generates an internal vacuum and sucks the prey inside.
Examples : Utricularia
Lobster-pot Traps
The Lobster-pot traps are also called corkscrew traps. These kind of plants bear Y-shaped modified leaves with inward -pointing bristles. These traps allow the prey to enter but make it difficult to exit. The inward-pointing hairs force the prey to move in a particular direction and obstruct the exit path. The prey is pushed into the lower arm where it is digested.
Examples :  Genlisea
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