Centipede Totally Explained

Everything about Centipede totally explained

Centipedes (from Latin prefix, "hundred", and Greek podos, "foot") are arthropods belonging to the class Chilopoda and the Subphylum Myriapoda. They are elongated metameric animals with one pair of legs per body segment. A key trait uniting this group is a pair of poison claws or forcipules formed from a modified first appendage. This also means that centipedes are an exclusively predatory taxa, which is uncommon.
Centipedes normally have a drab coloration combining shades of brown and red. and subterranean species may lack pigmentation and many tropical Scolopendromorphs have bright aposematic colors. Size can range from a few millimeters in the smaller Lithobiomorphs and Geophilomorphs to about a foot in the largest Scolopendromorphs.
Worldwide there are estimated to be 8,000 species . Currently there are about 3,000 described species. Geographically, centipedes have a wide range, which reaches beyond the Arctic Circle . Centipedes are found in an array of terrestrial habitats from tropical rainforests to deserts. Within these habitats centipedes require a moist micro-habitat due to their rapid rates of water loss. Accordingly, they're found in soil and leaf litter, under stones and deadwood, and inside logs. In addition, centipedes are among the largest terrestrial invertebrate predators and often they contribute a significant proportion to invertebrate predatory biomass in terrestrial ecosystems.

Anatomy

Centipedes have elongated dorsal-ventrally flattened bodies, and comprise two segmented tagmata; a head and trunk, which bear different hox gene expression. Each segment bears a single pair of legs and has a dorsal plate (tergite) and a ventral plate (sternite). Laterally each segment has a soft less scelerotized region known as the plueral membrane. This is where the spiracles for gas exchange are located in all orders except for the Scutigeromorpha (where they're located mid dorsally). The legs are segmented and segments are named proximal to distal: coxa, trachanter, prefemur, femur, tibia, and tarsus. Each leg terminates in a claw.
   At the anterior end of the centipede is the head. Dorsally the head consists of a cephalic plate which is distinct in appearance from the tergites. Laterally on the head some centipedes have eyes. The order Geophilomorpha is blind. Scutigeromorphs have compound eyes and the other orders have no eyes or simple ocelli ranging from one pair to many. The ventral view of the head reveals the centipede's most prominent characteristic, its poison claws or forcipules. There are also three pairs of mouthparts all derived from the modification of appendages. There is a mandible with a first maxillae ventral to it and a second maxillae ventral to the first. These mouthparts are used for both feeding and grooming. At the anterior of the head there's a pair of antennae which vary in length and number of segments (except for the Geophilomorpha where the number of segments is fixed at 14).
   The posterior end of a centipede has a conspicuous pair of legs named the ultimate or anal legs. These legs are not used for walking and are usually morphologically distinct from other pairs. Instead, they're used for defense and mating and so they often are morphologically distinct between the sexes. Ultimate legs can be inflated, excessively spined, and or morphologically complex with crests and furrows. The sexual organs are also located on the posterior end of the centipede. Sexual organs are externally visible in Scutigeromorpha and Lithobiomorpha, and some Geophilomorpha whereby males and females are easily distinguished. Scolopendromorpha don't have externally visible sexual organs, which makes sexing difficult. Scolopendromorph females may be larger or wider than males. Precise determination of sex can be accomplished upon dissection or by gently applying pressure and warm water to the genital sternite of a specimen to cause the sexual organs to emerge externally.
   It also notable that centipedes have distinct sensory structures. The Tomosvary organ in Lithobiomorphs and Scutigeromorphs is located just anterior to the position of the eyes. The organ appears externally as an ellipse and its function is largely unknown. It has been suggested that it's a pressure, light, or humidity sensor. There is some evidence that it functions as a pressure sensor to detect sounds . There are mechanoreceptors in the form of spines or hairs covering the legs and antennae. Lithobiomorphs have coxal pores on the ventral surface of the coxae of legs 12-15 in adults. These pores are present in pore fields consisting of 3-4 rows of pores. They are suspected to function in both osmoregulation and pheromone release . Pore fields are found on some Geophilomorph and Scolopendromorph species on various sternites and on the ultimate coxae. It isn't certain if their function is similair across the orders.

Hazards to humans

Some species of centipedes can be hazardous to humans because of their poisonous bites. Although a bite to an adult human may only be painful, to those with allergies that are similar to that of bee stings and small children are at greater risk.

Evolution

Internal phylogeny of the Chilopoda. The upper three groups form the paraphyletic Anamorpha. The orders of centipedes are considered below, from primitive to derived.

Scutigeromorpha

The Scutigeromorpha are anamorphic, reaching 15 leg-bearing segments in length. They are very fast creatures, and able to withstand falling at great speed: they reach up to 15 body-lengths per second when dropped, surviving the fall.
They are the only centipede group to retain their original compound eyes, with which a crystalline layer analogous to that seen in chelicerates and insects can be observed. They also bear long and multisegmented antennae. Adaptions to a burrowing lifestyle has led to the degeneration of compound eyes in other orders. This feature is of great use in phylogenetic anaylsis.
The group is the sole representative of the Notostigmomorpha, defined by having single spiracle openings on the back of their ventral plates. The more derived groups bear a plurality of spiracular openings on their sides, and are termed the Pleurostigmomorpha. Some even have 7 unpaired spiracles that can be found along the middorsal line and closer to their posterior section of tergites.

Geophilomorpha

The Geophilomorpha are the most derived group of centipedes, and bear upwards of 27 leg-bearing segments. They are without fail eyeless and blind, and bear spiracles on all leg-bearing segments - in contrast to other groups, who only bear them on their 3rd, 5th, 8th, 10th and 12th segments -- a "mid-body break", accompanied by a change in tagmatic shape, occurring roughly at the interchange from odd to even segments. This group, at 1260 spp. the most diverse, also contains the largest and leggiest specimens at 29 or more pairs of legs. They also have 14 segmented antennae.

List of common species

Arizona tiger centipede Scolopendra polymorpha

Blue ring centipede Ethmostigmus trigonopodus

Earth centipede Pachymerium ferrugineum

Feather tail centipede Alipes sp.

Galápagos centipede Scolopendra galapagoensis

Giant Sonoran centipede Scolopendra heros

House centipede Scutigera coleoptrata

Peruvian giant orange leg centipede Scolopendra gigantea

Red-headed centipede Scolopendra morsitans

Stone centipede Lithobius forficatus

Vietnamese centipede Scolopendra subspinipesFurther Information

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