The Evolution of Spiders - How Arachnids Came To Be On Earth

The Concept of Evolution

Perhaps all creatures on earth aren't what they were as they are now. At some point in time in the past, they must have looked differently in some way at least. And it wasn't only until eventually that they have changed form because of a naturally occurring compelling situation. This is the idea of natural organic evolution - a process that every creature on earth has somehow undergone at one point in time.

There are however certain species on earth that haven't undergone evolution, or that their evolution is quite negligible that they still do look the same as they were first conceived on the planet. Usually, these creatures that haven't undergone or have minor evolution are severely endangered or already extinct. The reason why this is the plausible scenario to organisms that have barely undergone evolution is because they haven't undergone evolution, they have failed to adapt in the natural selections over time. Evolution's purpose is to progress an organisms form in such a way that it will be able to blend in to the ever changing natural situations.

As time passes by, the environment changes, either become harsher or milder, and an organism would have to adapt to it in any way in order to survive, until eventually it will reach its ultimate form. Unless of course, the creature is already sufficiently formed as it is when it first came to earth, like for example, sharks. Sharks have not undergone through evolution because they apparently don't need to. They are very sufficient and perhaps efficient predators already in their original forms, hence evolution didn't take place. But for some others, they would have to or otherwise, they would have been long extinct.

However, not every organism on earth is endowed with the capability to evolve. This is the very reason why there are lots of creatures in the past that remained in the past. The process of eliminating organisms that haven't undergone evolution is called extinction. An organism may go extinct if it species have failed to compensate the change natural situations over time. Dinosaurs for example, have failed to sustain their generation because they have apparently exhausted their resources, thus leading them to migrate and eventually die in the transition.

However, there are some reptile species that evolved successfully, which eventually we now come to encounter as lizards, or snakes and what not. These are some of the successfully evolving species of time. There's no saying if what they are now are already their ultimate form though. Only time will be able to tell us whether if they will still evolve to another form or remain as they are. Human beings as well are perhaps, theoretically, not yet in their ultimate form. Who knows, when the time and environment deems necessary, we may have to grow wings in order to adapt to our surroundings. The process of evolution is uncertain, but more than half the time generally beneficial. And this is the very reason why spiders as well have undergone through it.

Arachnid Evolution

Spiders as organisms of earth have undergone through evolution. And considering their minute sizes, evolution if most likely necessary to them than any other species. Everything that they have now is a product of progressive and successful evolution. In return, they have become much more efficient hunters commensurate to their targets; the ultimate bug hunters of the era.

Spiders' evolution took place 400 million years ago. The first spiders that ever roamed the earth were relatively larger in size compared to what they are now. Still, the body of the first spiders were segmented. The only difference with the spiders segmented body before than today is that most of the spiders at present have non-segmented abdomens, while the spiders before have more than just single segmentations. There are certain species however, that remained to have an apparently relating segmented form as their predecessors. The spiders that belong to the suborder Mesothelae still display the same form abdominal segmentation as the first spiders. These spiders are also considered to be one of the primitive types of spiders that still roam the earth.

There are only a few fossil accounts uncovered for spiders. Perhaps the oldest spider fossil ever recorded in history was found in some prehistoric rocks in New York, dating way back to the Devonian Period (410 million to 360 million years ago). The fossil uncovered was surprisingly well preserved. The remarkable spider fossil was easily identified because of the presence certain common spider traits, particularly the spinnerets and chelicerae. There are also other fossil discoveries that dated way back in the Carboniferous Period (360 million to 290 million years ago). However, a fewer account of spider fossils were found that dated sometime during the Mesozoic Era (240 million to 65 million years ago).

On the other side of the topic, finding web fossils is a rather improbable scenario. Spiders' webs rarely present themselves as fossils in rocks. There are a few fossil discoveries, but they only contain bits and pieces of the entire thing. However, from those web-fossil discoveries scientists were able to deduce what kind of webs the first spiders produce in their time. Scientists have theorized that the ancestral spiders built much more irregular looking webs and they were most likely created near the ground. Furthermore, the scientists additionally deduced that the much more regular looking webs created on higher grounds (trees, taller plants, etc.) have only evolved later. Orb webs for example, may have only evolved later when spiders began hunting insects that thrive on the higher grounds. Some scientists have also theorized that the evolution of certain species have catalyzed the evolution of some other insects as well, and vice versa. In the attempt of some insects to escape ensnarement from ground lurking spiders, they may have developed wings in order to fly over their spider predators. At some time later, spiders have had developed aerial webs to catch insects that fly on higher ground. The idea is a compensating evolution for both species.