Centipedes, with their numerous legs, often lead to misconceptions about their exact limb count. While their name suggests a precise number, this is not biologically accurate. This article clarifies the truth about centipede leg counts, explores the origin of their misleading name, and distinguishes them from similar multi-legged creatures.
The Varied Number of Centipede Legs
Contrary to popular belief, centipedes do not have exactly 100 legs. The actual number of legs varies significantly by species and can even differ within a species as an individual grows. Centipedes are characterized by having one pair of legs per body segment.
The total number of legs typically ranges from 15 to 191 pairs, or 30 to over 300 individual legs. For instance, the common house centipede, Scutigera coleoptrata, usually possesses 15 pairs of legs, totaling 30 legs. In contrast, some soil centipedes (order Geophilomorpha) can have as many as 177 pairs of legs, resulting in 354 individual limbs.
A unique aspect of centipede anatomy is that the number of leg pairs is always an odd number. This arrangement allows for efficient movement across various terrains, assisting in their predatory lifestyle.
Understanding the “Centipede” Name
The name “centipede” is a primary source of the widespread misconception about their leg count. This term originates from Latin, where “centi-” means “hundred” and “pes” means “foot,” literally translating to “hundred-footed.” This etymology suggests the name was likely given to describe the general impression of having many legs, rather than an exact numerical quantity. Ancient observers, seeing these creatures with their numerous, rapidly moving limbs, may have simply used “hundred” as a descriptor for “very many” or “a great multitude.”
Centipedes and Millipedes: A Clear Distinction
Centipedes are often confused with millipedes, another group of multi-legged arthropods. A key difference lies in their leg arrangement: centipedes possess one pair of legs per body segment, while millipedes have two pairs of legs per apparent body segment. This distinction arises because millipede segments are actually fused pairs of segments.
Beyond leg count, their body shapes and behaviors also differ. Centipedes typically have flattened bodies and move quickly, reflecting their predatory nature. They are active hunters, using their speed and venom to capture prey.
Millipedes, conversely, tend to have more rounded, cylindrical bodies and move much slower, often in a wave-like motion. They are primarily detritivores, feeding on decaying organic matter and playing a role in decomposition.