Centipedes are often encountered in homes and gardens. Their multi-legged appearance often causes confusion about their classification, particularly whether they are insects. Despite superficial similarities, centipedes belong to a distinct biological group. This article clarifies their biological classification and highlights the key differences that set them apart from insects.
Defining Insects
Insects are a diverse group of animals recognized by specific anatomical features. Adult insects have a body divided into three distinct regions: the head, thorax, and abdomen. The head typically bears antennae and compound eyes, while the thorax is the middle section where legs and wings attach. Insects possess three pairs of jointed legs, totaling six, attached to the thorax; many species also have two pairs of wings, typically attached there. These features, along with an exoskeleton made of chitin, categorize them within the Class Insecta.
Defining Centipedes
Centipedes are predatory arthropods with elongated, flattened bodies composed of numerous segments. Each body segment, except for the last two, typically bears a single pair of legs. A distinctive feature of centipedes is the presence of forcipules, modified legs located on the first body segment behind the head, which are pincer-like appendages containing venom glands used to immobilize prey. They also have a pair of antennae at the front of their rounded or flattened head and are classified under the Class Chilopoda.
The Arthropod Connection: Where Centipedes and Insects Differ
Both insects and centipedes belong to the large biological group known as the Phylum Arthropoda, which means they share the characteristic of having jointed legs and an exoskeleton. This shared phylum is a primary reason for the common confusion between these two groups. Despite this overarching connection, insects and centipedes are classified into different biological classes, highlighting their fundamental distinctions.
A key difference lies in their body segmentation. Insects have three distinct body parts: a head, a thorax, and an abdomen. In contrast, centipedes have many body segments that are less differentiated into distinct regions.
The number of legs also distinguishes them. Insects have six legs, or three pairs, all attached to the thorax. Centipedes, however, have many pairs of legs, with one pair per body segment. The name “centipede” literally means “one hundred feet,” though the actual number of legs can vary widely depending on the species, ranging from 30 to over 300, but always with one pair per segment.
Another significant difference is the presence of venom claws. Centipedes possess specialized venom claws, or forcipules, which are modified legs used for subduing prey. Insects lack these venomous appendages. Many insects develop wings, a feature entirely absent in centipedes. While insects can fly, centipedes are solely terrestrial.