Experts found that spiders had used their appendages in very quirky ways, including capturing food and any other forms of movement.
According to a report on Live Science, scientists have traced why spiders have eight legs and where do they use these legs. Experts found out that the parents of eight-legged spiders could be traced to around 500 million years ago or during the middle Cambrian Period.
They said the species that existed during those times were those that belong to the chelicerate lineage, or the group of arthropods that contains spiders.
Researchers also dug deeper and discovered that lobopods or those that inhabit the oceans could be dated back to 541 million years ago. They explained that lobopods are those wormlike creatures that have segmented bodies wherein each segment possesses identical pairs of "short, stubby legs."
Evolution of lobopods
During the spiders' evolution period, the lobopods started to specialize their legs and fuse their body segments. Researchers have found out that the early chelicerates were likely to have fused their small body segments into two big ones, creating the head and the abdomen.
It was, however, undetermined why the head portion was able to keep the legs while the abdomen had lost them.
Developmental biologist Nipam Patel revealed that the legs were actually part of the mouth.
In an entry posted on The Verve Times, the first pair of appendages during the lobopod stage were used for sensing and grabbing food. Meanwhile, the front appendages also turned into antennae that will be utilized for sensing instead of feeding.
On the other hand, the chelicerates had transformed these appendages into fangs, and upon this transformation, they lose their sensory function.
Researchers also noted that the chelicerates' second pair of legs had evolved into pedipalps, or those that are described as grabby appendages. They said that the following four pairs of legs had retained their roles and usage as walking appendages, while all the other subsequent appendages had been lost - except for the spinnerets.
Read Also: Researchers Explain Unique Behavior of a Spider Species
Characteristics of spiders
The Cornell University described spiders as having two body parts with eight legs and chelicerae or fangs.
Research said that the spiders could be found anywhere except for the ocean and the Antarctica.
They usually eat through the use of their venom that can kill or paralyze their preys from hole in fangs or through the process of external digestion wherein the digestive enzymes acts outside of the body to liquify their prey.
Spiders usually grow through the process of moulting wherein their external skeleton would undergo a shedding process. According to scientists, this process is a very significant and risky part of the spiders' lives.
Spiders are categorized as arachnids. Other arachnids will include the scorpions, whip scorpions or vinegaroons, tailless whip scorpions, harvestmen or daddy-long-legs, mites and ticks, solfugids or sun spiders, and pseudoscorpions.
According to experts, the closest relative of the arachnids are the horseshoe crabs due to their legs, the body parts that they possess, as well as their chelicerae.
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