What are spiders?
Spiders are ubiquitous predators, occurring in virtually all terrestrial habitats. They have two main body segments (the prosoma or cephalothorax, and opisthosoma or abdomen) and eight walking legs. Spiders have modified mouthparts called chelicerae to deliver venom. Importantly, these are not mandibles and spiders rarely chew their food; they are on a liquid diet. They have modified limbs between the chelicerae and walking legs called pedipalps, which are modified in males as an intromittent organ; in other words, the male passes his sperm to females using these unique structures. Last but not least, spiders have spinnerets with spigots for extruding silk, which they use for myriad purposes. Beyond this, spiders are incredibly diverse, with different shapes, sizes, and colors; even their eight eyes may be reduced to none based on their habitat pressures.
While many people may conflate spiders with arachnids, arachnids are a super diverse clade including scorpions, harvestmen (daddy long legs), scorpions, whip spiders, whip scorpions, and others. Though other groups may have eight legs or two segments, only spiders produce silk and have repurposed their palps in males as intromittent organs.
While many people may conflate spiders with arachnids, arachnids are a super diverse clade including scorpions, harvestmen (daddy long legs), scorpions, whip spiders, whip scorpions, and others. Though other groups may have eight legs or two segments, only spiders produce silk and have repurposed their palps in males as intromittent organs.
Why spiders?
When I tell people I study spiders, the response is usually one of two things: cool! or gross, why? Spiders are one of those animal groups that invoke fear and fascination. The reasons for the negative reputation of spiders are clear - people think of them as dangerous (most are not), they often occur in close proximity to people, some of them grow to large sizes, and more. Still, many people appreciate spiders as amazing architects and important predators of pest insects. Spiders are a topic of research for many scientists for a number of reasons. Their ubiquity makes some of them easy to study. Like all invertebrate groups, little is known about them individually or in hotspots of diversity; that is, many are unknown to science. They have many captivating behaviors, from spinning webs and wrapping prey to courtship rituals to maternal care. Their sizes vary by orders of magnitude across the order, with different sexes or closely related species differing wildly in shape and size. But for all of this, there is also a solid foundation of spider research stretching back centuries that gives a framework for asking these interesting question rather than starting for scratch. In short, there is still a lot to know about spiders!
