What can be the consequence to an animal, of fatal attraction towards a plant? It could lead to the ultimate indignity for an animal — that is, to be killed by a plant! I am talking about carnivorous plants here. These do not have muscles or a nervous system, unlike their prey, but still manage to outsmart them.
Imagine this — you are a fly and you are looking for sweet, nutritious nectar. The scent of nectar coming from a scarlet flower patch catches your attention. As the fleshy pad of the ruddy leaf promises you a comfortable perch, you go with the flow. It seems as if this is the sweetest nectar, but what is this darkness descending on you? You look around and in a moment you realise that the world has closed in on you because the petals of the flower have folded on you and the spines along their edges interlock like the teeth of a jaw trap. Without a second chance, the chamber that lured you with nectar is filled with enzymes which gorge on your flesh alive! What’s more, you cannot even escape as the waxy surface of the chamber prevents it. This is what happens in a Venus flytrap.
There is another carnivorous plant, the pitcher plant. It has a leaf shaped like a champagne flute into which insects and other bigger animals fall and drown in the soup of digestive enzymes. Pitcher plants fold their leaves into a longish tube-like structure in which insects and even frogs can slip and fall into. The slippery side walls of the tube then prevent the trapped prey from escaping.
The Bladderwort is a carnivorous plant, found underwater. It pumps out water from its bladders, lowering the pressure inside. When a water flea or any other aquatic insect stimulates the hair on the bladderwort, its flap opens and the pressure inside the chamber rapidly draws in water and along with it the hapless and unsuspecting prey.
But what could have pushed carnivorous plants towards a taste for meat? It has been found that when scientists feed pitcher plants with more bugs, they grow bigger. However, plants get different types of benefits from eating animals.
Carnivorous animals absorb carbon from proteins and fat in meat to build muscles and store energy. Carnivorous plants eat meat to get nitrogen, phosphorus and other critical elements to harvest enzymes that will help them to harvest sunlight. Thus, meat helps the carnivorous plants do what other plants do — grow by grabbing sunlight.
However, they are inefficient in utilising sunlight to form tissue. This is so because carnivorous plants are not like ordinary plants with flat leaf surfaces. They have to manipulate leaves to build a prey-catching apparatus — the enzymes, the pumps and sticky hair. Thus little of the leaf surface is left for sunlight absorption. However, under special conditions, the benefits of being a carnivore outweigh the costs. For instance, the habitat where carnivorous plants typically survive are bogs and peats which are low in nitrogen and phosphorus. Under these low concentrations, carnivorous plants can survive much better that other plants as they draw in their nitrogen and phosphorus from meat.
Also, bogs and peats typically enjoy a lot of sunlight, hence the inefficiency of the carnivorous plants in acquiring sunlight for photosynthesis is taken care of.
Unfortunately, these marginal habitats, the bogs, peats, marshes and fens in which these carnivorous beauties thrive are also the most vulnerable as they are sensitive to environmental changes.
Agricultural runoffs and industrial effluents add a heavy dose of nitrogen to the system. These plants are attuned to low levels of nitrogen and do not fare well in an environment with high nitrogen as other plants easily overtake them.
Let’s not forget the human interest in carnivorous plants as well. If the reckless trading activities go unchecked, carnivorous plants will soon dwindle in number and their evolutionary uniqueness will cease to exist.