Centipede

Centipedes, historically associated with the Neo-Latin terms for hundred and foot, are predatory arthropods belonging to the class Chilopoda within the subphylum Myriapoda. This broader group also includes millipedes and other multilegged organisms. Centipedes are characterised by elongated, segmented bodies in which each segment bears a single pair of legs. Although commonly linked with the idea of having one hundred legs, no species possesses exactly that number; instead, centipedes display a wide range of odd-numbered leg pairs, from as few as fifteen to well over one hundred and ninety. Their global distribution spans tropical rainforests, temperate woodlands, grasslands and deserts, yet they remain strictly terrestrial and dependent on moist microhabitats owing to the absence of a protective waxy cuticle. Universally venomous, they subdue prey using modified anterior limbs known as forcipules, which inject venom capable of immobilising a wide array of small invertebrates.

Morphology and General Description

Centipedes display a dorsoventrally flattened or sometimes rounded body form, beginning with a distinct head capsule. This head carries a pair of long, filamentous antennae used extensively for environmental sensing. Mouthparts include elongated mandibles and two pairs of maxillae, the first pair contributing to the formation of a lower lip equipped with short palps. The first pair of trunk limbs is transformed into forcipules, sharply pointed appendages containing venom glands. These are not true mouthparts but modified legs specialised for predation.
Body size varies considerably among the major orders. Small lithobiomorph and geophilomorph species may measure only a few millimetres, whereas scolopendromorph centipedes can reach several tens of centimetres in length. The trunk typically comprises a minimum of fifteen segments, nearly all bearing legs. Each successive leg pair is slightly longer than the pair before it, a feature that prevents interference during locomotion. A terminal telson houses reproductive openings and supports the final pair of legs, which play no role in walking.
Respiration occurs through a tracheal system, usually with a single spiracle per segment, while excretion relies on a pair of Malpighian tubules. The digestive tract consists of a simple tube supported by digestive glands associated with the anterior feeding structures.

Sensory Structures

Centipede sensory capabilities vary widely between taxa. Many species lack true eyes altogether, whereas others possess simple ocelli arranged singly or in clusters. Even when present, these organs detect only light intensity rather than detailed images. Some species rely heavily on their elongated antennae for navigation and prey detection.
An unusual sensory adaptation is the organ of Tömösváry, located near the base of the antennae. This disc-shaped structure with a central pore is believed to detect vibrations, potentially providing rudimentary auditory perception. In certain taxa, the first pair of legs also acts as sensory appendages, directed backwards rather than forwards, a notable deviation from patterns seen in most arthropods.

Forcipules and Venom Delivery

Forcipules constitute a defining feature of centipedes. Derived from the first trunk leg pair, these appendages extend forward beneath the head, forming powerful pincer-like structures. Within each forcipule runs a duct from a venom gland situated in the head capsule, allowing delivery of venom through the claw tips. This system enables centipedes to immobilise prey rapidly, a crucial adaptation for these fast-moving predators.

Ultimate Legs

The final leg pair, referred to as ultimate legs, exhibits significant morphological and behavioural specialisation. These appendages do not contribute to locomotion. Instead, depending on the species, they may be elongated, thickened, forceps-like or leaf-shaped. In some taxa, they participate in defensive displays, grasping predators or supporting the body as the centipede suspends itself from vegetation or other structures.
Ultimate legs can also serve sensory functions, as glandular pores are more common on these limbs than on the walking legs. Sexual dimorphism is often pronounced, suggesting a role in courtship. Some species exhibit stridulation with the ultimate legs, producing sounds used for defence or communication; for example, the genus Alipes generates a rustling noise by vibrating its leaf-like structures.

Distinction from Millipedes

Despite superficial similarities, centipedes and millipedes differ fundamentally in morphology and ecology. Millipedes possess two pairs of legs per segment, feeding primarily on decaying plant matter, whereas centipedes have one pair per segment and are strictly carnivorous. Their heads also differ: centipedes have long, threadlike antennae and venom-bearing forcipules, while millipedes possess short, elbowed antennae and lack venomous appendages. Both groups possess Tömösváry organs, yet the functional roles of these structures may vary.

Reproduction and Life History

Centipedes reproduce without copulation. The male deposits a spermatophore on the substrate, which the female later collects. Egg-laying generally occurs in warm seasons in temperate regions. Some species are parthenogenetic. Females provide notable parental care, curling around their eggs and young to protect them and grooming them to reduce fungal or bacterial infection.
Longevity exceeds that of most insects. Species such as Lithobius forficatus often live five to six years, while some Scolopendra species survive for more than a decade. Limited egg production, extended developmental periods and relatively slow maturation contribute to their classification as K-selected organisms.

Development and Segmentation

Centipede developmental strategies fall into two major categories: anamorphosis and epimorphosis. In anamorphic groups, including lithobiomorphs, scutigeromorphs and craterostigmomorphs, juveniles hatch with fewer than the adult complement of leg-bearing segments and acquire additional segments and legs with successive moults. For instance, the house centipede Scutigera coleoptrata begins life with four pairs of legs and gradually increases to fifteen pairs upon reaching maturity.
Epimorphic centipedes, comprising the geophilomorphs and scolopendromorphs, hatch with the full number of segments and do not acquire more legs during later moults. These groups include the longest known species. Within geophilomorphs, segment numbers vary both within and between populations, with females generally possessing more segments than males. The total number of leg-bearing segments is species-specific and always odd, consistent with the absence of species holding exactly one hundred legs.
Segmentation follows a two-phase developmental mechanism. The anterior head region forms a fixed, odd number of segments under the regulation of Hox genes, while the posterior region expands by producing prepattern units that subsequently divide into segment pairs. This process is controlled by an oscillating system comparable to mechanisms seen in vertebrate segmentation.

Ecology and Diet

Centipedes act as important mid-level predators within soil and leaf-litter ecosystems. Their feeding habits are predominantly carnivorous, though some species display specialist tendencies based on habitat. Typical prey includes earthworms, fly larvae, springtails and other small arthropods, with some larger species capable of overpowering vertebrate juveniles. Moist environments remain essential for survival, as water loss occurs rapidly through their permeable cuticle. Consequently, centipedes are commonly nocturnal, remaining concealed under logs, stones and leaf litter during daylight hours.