When Spiders and Carnivorous Plants Team Up

Most people have heard of carnivorous plants such as the venus flytrap and pitcher plants. These plants are considered enemies of all insects and use trickery to lure in fresh insect prey for them to feast upon. However, it turns out that not all creepy crawlies are in danger from these carnivorous plants, and one in particular actually demonstrates a symbiotic relationship with them. There are several types of spiders that actually use carnivorous pitcher plants in Southeast Asia as their home. So, how do these spiders avoid getting eaten by the plants while being able to safely live inside them?

Pitcher plants still get the normal plant diet of sunlight and water, but they supplement this diet with insects. The plants use chemical and visual cues to lure insects to the nectar coating the outer lips of the pitcher-shaped part of the plant. The surface will often become slippery, particularly when it is raining, which sends many bugs tumbling inside the pitcher to be then broken down by digestive liquids. While this would be a deterrent to most, Yellow (Thomisus nepenthiphilus) and red (Misumenops nepenthicola) crab spiders actually use it to their advantage in order to make a home where the pickings are easy and plentiful.

These crab spiders seem to have figured out the trick to the pitcher plant’s insect trap, and adapted so that they could get some of the incoming food too. They actually hang out inside of the pitcher plants, avoiding the digestive liquid whenever possible, and wait for the insects to fall into their lap. When a bug is caught by the trap, falling inside the pitcher, the spiders ambush them, even diving after them straight into the liquid. Luckily for these spiders, they are able to extricate themselves from the liquid by using their own silk.

While this may appear to be a one-sided relationship, recent findings show that the pitcher plant also benefits from the presence of the spiders. The spiders are able to catch some of the bigger, more fearsome insects that are difficult for the pitcher plant to catch. After the spiders are finished with their meal, they leave the leftover carcass in the liquid for the pitcher plant to finish. Researchers found that the pitcher plants with spiders inhabiting them, scored more insect meals than pitcher plants without them.

Have you ever seen a carnivorous plant with an insect stuck or trapped inside it?


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