Many people encounter small, multi-legged creatures in their homes and may mistake silverfish for centipedes. Despite sharing common household spaces, these are distinct organisms with unique characteristics. Understanding their differences helps in identification.
Identifying Silverfish
Silverfish are primitive, wingless insects, typically measuring between 7 to 19 mm (0.3 to 0.75 inches) in length. They possess a distinctive silvery-gray color and a tear-drop or carrot-shaped body that tapers towards the rear. Their bodies are covered in small, shiny scales, and they have two long antennae at the head and three bristle-like appendages extending from the rear. These nocturnal insects are agile and move rapidly.
Silverfish commonly inhabit damp, dark, and cool environments, such as basements, bathrooms, kitchens, and attics, where humidity levels are typically above 75%. They are scavengers with a diet rich in carbohydrates and proteins, feeding on items like paper, glue, bookbindings, wallpaper, cereals, and dried meats. While harmless to humans and not known to bite, silverfish can cause damage to household belongings and contaminate food sources.
Identifying Centipedes
Centipedes are predatory arthropods with an elongated, flattened, and segmented body. They typically range from 2.5 to 30 cm (1 to 12 inches) in length. A distinguishing feature is that each body segment bears a single pair of legs, with the total number of legs varying widely. Their coloration can vary, but they are often yellowish to dark brown, sometimes with darker stripes.
Centipedes are fast-moving nocturnal hunters, using their speed and venomous front legs, called forcipules, to capture prey. Their diet primarily consists of other insects and small invertebrates, including silverfish, spiders, and cockroaches. Centipedes prefer moist environments like under rocks, logs, and leaf litter outdoors, and indoors they are found in damp basements and bathrooms. While they can inflict a painful bite or sting using their forcipules, it rarely poses a serious threat to humans, often resulting in mild pain and swelling.
Key Distinctions Between Them
A fundamental difference between these two creatures lies in their biological classification; silverfish are insects. Centipedes, however, are myriapods. This distinction impacts their anatomical structure.
The most noticeable difference is their leg count and arrangement. Silverfish have only six legs, characteristic of insects. In contrast, centipedes possess numerous pairs of legs, with one pair per body segment, and their leg count varies greatly by species. Furthermore, silverfish have a distinctive carrot or tear-drop shaped body with three long, tail-like appendages at their rear. Centipedes, conversely, have an elongated, flattened body and lack these three tail-like structures.
Their feeding habits and potential to bite also differ. Silverfish are scavengers that consume starchy materials and cellulose, causing damage to property. They are not known to bite humans, as their mouthparts are designed for scraping tiny particles. Centipedes are predators, actively hunting and feeding on other insects. They can bite or sting with their venomous forcipules, though such incidents are usually minor for humans.