“Spiders are insects”

It's a widely held belief that spiders are insects, a common misconception that often stems from their shared presence in our homes and gardens, and their small, multi-legged appearance. Both spiders and insects belong to the larger phylum Arthropoda, which includes creatures with exoskeletons, segmented bodies, and jointed limbs. However, this is where their close kinship largely ends, as spiders belong to the class Arachnida, a distinct group from the class Insecta.

The scientific evidence clearly distinguishes spiders from insects through several key anatomical differences. Insects, like ants or butterflies, are characterized by having three distinct body segments—a head, a thorax, and an abdomen—and possess six legs. They also typically have antennae and, in many cases, wings. Spiders, on the other hand, have only two body segments: a cephalothorax (a fused head and thorax) and an abdomen. A defining feature of spiders and other arachnids is their eight legs, and they notably lack antennae and wings. These fundamental differences in body plan are crucial for their classification.

People commonly believe spiders are insects due to several factors. Their small size and often similar habitats lead to them being grouped together in casual observation. The general term "bug" is frequently used interchangeably for any small crawling creature, blurring the lines between different scientific classifications in everyday language. Without a deeper understanding of biology, the superficial similarities of being multi-legged invertebrates are often enough to lead to this widespread, yet incorrect, categorization.