By Obiabin Onukwugha
Spiders (order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom and spinnerets that extrude silk.
They are the largest order of arachnids and rank seventh in total species diversity among all orders of organisms.
Spiders are found worldwide on every continent except for Antarctica, and have become established in nearly every land habitat.
Reports say as of August 2022, 50,356 spider species in 132 families have been recorded by taxonomists.
However, there have been debate among scientists about how families should be classified, with over 20 different classifications proposed since 1900.
Unlike insects, spiders do not have antennae. In all except the most primitive group, the Mesothelae, spiders have the most centralized nervous systems of all arthropods, as all their ganglia are fused into one mass in the cephalothorax.
Spiders use a wide range of strategies to capture prey: trapping it in sticky webs, lassoing it with sticky bolas, mimicking the prey to avoid detection, or running it down.
They mostly detect prey by sensing vibrations, but the active hunters have acute vision, and hunters of the genus Portia show signs of intelligence in their choice of tactics and ability to develop new ones.
Spiders’ guts are too narrow to take solids, so they liquefy their food by flooding it with digestive enzymes. They also grind food with the bases of their pedipalps, as arachnids do not have the mandibles that crustaceans and insects have.
In most ecosystems, spiders act as agents of population control, ensuring insect numbers are not overwhelming. Identified as generalist consumers, they also prey on a variety of organisms beyond insects, regulating the density of the species they go after.
Spider social behavior ranges from precarious toleration, as in the widow spiders, to co-operative hunting and food-sharing.
Although most spiders live for at most two years, tarantulas and other mygalomorph spiders can live up to 25 years in captivity.
Female spiders tend to live longer than male spiders. Many male spiders reach maturity within two years and die after mating.
To avoid being eaten by the females, which are typically much larger, male spiders identify themselves to potential mates by a variety of complex courtship rituals.
Females weave silk egg-cases, each of which may contain hundreds of eggs. Females of many species care for their young, for example by carrying them around or by sharing food with them.
A minority of species are social, building communal webs that may house anywhere from a few to 50,000 individuals.
While the venom of a few species is dangerous to humans, scientists are now researching the use of spider venom in medicine and as non-polluting pesticides.
Spider silk provides a combination of lightness, strength and elasticity that is superior to that of synthetic materials, and spider silk genes have been inserted into mammals and plants to see if these can be used as silk factories.
As a result of their wide range of behaviors, spiders have become common symbols in art and mythology symbolizing various combinations of patience, cruelty and creative powers. An irrational fear of spiders is called arachnophobia.
Spiders have been the focus of stories and mythologies of various cultures for centuries.
Uttu, the ancient Sumerian goddess of weaving, was envisioned as a spider spinning her web. According to her main myth, she resisted her father Enki’s sexual advances by ensconcing herself in her web, but let him in after he promised her fresh produce as a marriage gift, thereby allowing him to intoxicate her with beer and rape her.
According to the story, Enki’s wife Ninhursag heard Uttu’s screams and rescued her. She removed Enki’s semen from her vagina and planted it in the ground, which produced eight previously non existent plants.
In a story told by the Roman poet Ovid in his Metamorphoses, Arachne (Ancient Greek), Spider was a Lydian girl who challenged the goddess Athena to a weaving contest. Arachne was said to have won, but Athena destroyed her tapestry out of jealousy, causing Arachne to hang herself. In an act of mercy, Athena brought Arachne back to life as the first spider.
There is also the story about the trickster-spider, Anansi, which is prominent in the folktales of West Africa and the Caribbean.
In some cultures, spiders have symbolized patience due to their hunting technique of setting webs and waiting for prey, as well as mischief and malice due to their venomous bites. The Italian tarantella is a dance to rid the young woman of the lustful effects of a spider bite.
