The Carboniferous period, a time when vegetation actively removed carbon from the atmosphere and generated oxygen, is full of intriguing stories. For instance, the story of insects. It was a time not just of “giant dragonflies.” It was a time when, in general, could emerge flying insects. After all, when envisioning the evolution of a future flyer, it’s important to understand that it needs to be heavy enough for the rudiments of wings to provide an advantage in making long jumps from branch to branch. And heavy insects could be only in carbon because only then was there enough oxygen in the atmosphere for a passively breathing insect with tracheae not to suffocate due to its large size.
But ancient insects were arthropods that regularly molted, just like crustaceans do today. This means that in order to molt, there was living tissue inside their chitinous wings. It’s difficult to fly with heavy, unfeathered wings. You can observe how they fly. day laborers — the last surviving insects, whose winged individuals molt.
And then some beetle had the idea that it wasn’t fitting for an adult to molt. So the wings were able to “shrink,” becoming lighter and stiffer. Enter the “ultimate predator” — the dragonfly. Yes, that beautiful and harmless little bug. Dragonflies, facing neither resistance nor deception, devoured almost everything that moved. This is despite the fact that their wings, by modern standards, are primitive and do not fold, and the larvae of some species can breathe like yogis, but only through their rear ends (anal). gills. )..
How. and any other “absolute predator,” which, by the way, can also be referred to as person Dragonflies have created an ecological disaster. The world of insects, as we see it now, and indeed the entire world above them in the food chain, emerged thanks to dragonflies. Some insects, like mayflies, which are evolutionary contemporaries of dragonflies, realized that “glowing” in the air is dangerous and live only for a day—to reproduce and lay eggs, from which larvae that live for several years will hatch. Some retreated underground, beneath the bark, or under logs, transforming one pair of wings into a shell or losing their wings altogether. Some drastically reduced in size and ceased to be attractive to large predators. Some learned to use the “herring tactic,” forming large swarms that scatter in different directions when attacked. Some, like grasshoppers, learned to jump very sharply. Some, like cockroaches, unlearned how to fly. Some, like flies, learned to fly quickly along clever and unpredictable trajectories. Some developed venom. Some learned to live in families.
A. one. Among the species that were pushed to the periphery of life by their dragonfly relatives, there was one that had to sample wood, for which it acquired clever symbiotic bacteria capable of breaking down lignin—a natural mixture of polymers that makes up wood. By starting to recycle the piles of wood and thus returning carbon back into the cycle, it significantly contributed, along with other beetles that we now call pests, to the reduction of living forests and their dead deposits. This led to a) a decrease in oxygen generation and b) the return of carbon, in the form of carbon dioxide, back into the atmosphere.
The reduction of oxygen levels in the atmosphere forced dragonflies to shrink to their modern sizes and stop causing chaos. Essentially, dragonflies ate their own future. If it weren’t for dragonflies, insects would still be feeding on the juices, spores, and pollen of (gymnosperm) plants, coal would still be forming, and brightly colored cockroaches would be comfortably fluttering under the lampshade in the kitchen.