Centipedes are arthropods found globally, exhibiting unique visual characteristics. Understanding their appearance provides insight into their predatory lifestyle and distinguishes them from other multi-legged invertebrates.
Key Identifying Features
Centipedes possess an elongated, segmented body, typically flattened to navigate tight spaces. The body divides into a head and a trunk composed of numerous segments. Each body segment, except for the very last two and the one bearing the forcipules, carries a single pair of legs. The number of leg pairs varies significantly by species, ranging from 15 pairs to as many as 191 pairs, but always an odd number. Legs are positioned laterally, enabling swift movement.
The head features long, segmented antennae, which are crucial sensory organs for sensing their environment and locating prey. Many centipede species have poor vision or lack true eyes. While some possess simple eyes (ocelli) or clusters resembling compound eyes, these generally only detect changes in light, not detailed images.
Forcipules, also known as venom claws, are a unique centipede feature. These pincer-like appendages are modified first legs, located just behind the head. They contain venom glands and are used to capture and inject venom into prey. The last pair of legs on many centipedes can be elongated, functioning as rear-facing antennae to aid navigation and sensing when moving backward.
Size and Color Diversity
Centipedes exhibit considerable variation in size, spanning from small species measuring only a few millimeters in length to much larger varieties found in tropical regions. For instance, some smaller lithobiomorphs and geophilomorphs can be just a few millimeters long, while the largest known species, Scolopendra gigantea, can exceed 30 centimeters (12 inches) in length.
Centipede coloration is diverse, ranging from earthy tones like browns, yellows, and dark grays to vibrant reds, oranges, greens, or blues, especially in tropical climates. For example, the giant red-headed centipede (Scolopendra heros) has a black body, yellow legs, and a rusty-red head. These patterns serve purposes like camouflage or aposematism, where bright colors warn predators of their venomous nature.
The exoskeleton can be smooth or rough. This chitinous outer layer protects internal organs and serves as a muscle attachment point.
Differentiating from Similar Creatures
Centipedes are often confused with other multi-legged arthropods, especially millipedes, due to their segmented bodies and numerous legs. The most significant difference is leg arrangement: centipedes have one pair of legs per body segment, while millipedes have two pairs on most segments.
Body shape is another differentiator. Centipedes have a flattened, dorsoventrally compressed body, aiding their quick, agile movements as predators. Millipedes, in contrast, usually have a more rounded or cylindrical body, appearing denser and more robust. Their antennae also differ: centipedes have longer, thread-like antennae, while millipedes have shorter, often club-shaped ones.
Movement also provides visual cues. Centipedes are known for fast, erratic movements, darting quickly across surfaces. Millipedes, with two pairs of legs per segment, move much more slowly with a wave-like motion. When disturbed, a centipede might attempt to quickly escape, while a millipede often curls into a tight spiral. Centipedes also differ from worms, which lack legs, and from beetle larvae, which have fewer segments and different leg arrangements.