The centipede belongs to the group of invertebrate animals of the phylum of arthropods and of the Chilopoda class (kilopods). Quilópodes is a Greek word that means “kilo” = “mil” and “podos” = “paws”. That is, it is a group of animals that has as main characteristic, the large amount of articulated legs .
The kilopods are small, generally measuring 2 to 7 cm in length, and have a body composed of several interconnected “rings”, with one pair of legs per segment. The groups of animals that represent the kilopods are centipedes and lacraias. Currently, there are almost 3,000 species of kilopods.
The repulsive appearance culturally perceived by most human beings is probably the reason why centipedes are considered to be dangerous and almost always exterminated.
Centipedes are kilopods, which means “a thousand legs” (Photo: depositphotos)
They are animals that have a slender, long, segmented and flattened dorsoventrally or round body, resembling snake lice in general. They have a well-differentiated head with a pair of articulated antennas and jaws, but there is no differentiation between thorax and abdomen.
Centipedes are usually brown in color, but they can have a wide variety of colors, including light shades of red, black, yellow and green or even transverse blue bands on their backs.
In the first segment of the centipede’s body are the venom glands – the sting (Photo: depositphotos)
Centipedes have one pair of legs per segment, the number of which ranges from 15 to more than 180. The last pair of legs is sensory and defensive and not locomotor, and the last two segments of the trunk have no legs. The largest centipede, Scolopendra gigantea , reaches almost 30 cm in length .
Scolopendra gigantea can reach almost 30 cm in length (Photo: depositphotos)
Kilopod animals are active predators, carnivores and feed on small arthropods, worms, insects, such as: beetles, larvae, earthworms, and even some small vertebrates, such as: birds, frogs and snakes. All of these animals are captured alive, immobilized and inoculated by venom .
The prey is detected and located by contact through the antennae, or with the legs, and then it is captured and killed, or stunned with the poison claws. Certain species do not feed when deprived of their antennae.
Digestion takes place through a tube that begins in the mouth and ends in the anus. Debris passes from the blood, through the thin walls of Malpighi’s tubules to the lumen, and then to the intestine.
Gas exchange and excretion
Gas exchanges are carried out through a tracheal system. There are a couple of spiracles per segment. The spiral, which cannot be closed, opens in an atrium covered with cuticular hairs (trichomes) that can reduce desiccation or prevent the entry of dust particles.
The tracheal tubes open at the base of the atrium and end in small tubes filled with liquid that supply oxygen directly to various tissues.
The kilopod excretory system has two structures that filter body fluids. They are called Malpighi and have one or two openings to perform excretion.
Much of the nitrogenous waste is excreted as ammonia and not as uric acid. Centipedes require a humid environment to maintain an appropriate water balance, as the coat does not have the waxy cuticle of insects and arachnids.
In males there are 1 to 24 testicles, located above the midgut. The testicles are connected to a single pair of sperm ducts that open through a median gonopore on the ventral side of the genital segment.
Sperm transmission is indirect in kilopods. In general, the male builds a small web of silk threads secreted by a spinner located in the genital atrium. A spermatophore is placed on the web. The female takes the spermatophore and places it in her genital opening. The gonopods of each sex assist in the manipulation of the spermatophore.
The male usually only produces a spermatophore when he meets the female, and there is often an initial cutting behavior. This behavior can last up to an hour before the male deposits the spermatophore.
The male then “signals” to the female by touching her antennae and she responds by crawling towards the male and catching the spermatophore.
After cutting, the female crawls towards the male to perform the mating (Photo: depositphotos)
The venom of the centipede
In the first segment of the centipede’s body there is a structure called forcipula, where the venom glands are – the sting – poison inoculating device. In Brazil, there are about ten species whose bite is feared, the main ones being Scolopendra viridicornis, S. subspinipes, Otostigmus scabricauda, Cryptops iheringi and Octocryptops ferrugineus . The viridicornis S. is the most common in our country.
Centipede venom has been poorly studied, but it is known that, at least in some species, it contains proteins, lipids, lipoproteins, histamine, hyaluronidase, polypeptides and proteinases.
Generally, the symptoms resulting from a centipede’s bite are only local, with instantaneous, intense pain , as if it were a burning sensation, which ceases in approximately 24 hours, accompanied by hyperemia and local edema.
In more rare cases, irradiated pain, local necrosis, tachycardia, lymphadenitis and systemic symptoms such as fever, tremors, chills, sweating, dyspnoea, headache, vomiting and anxiety may occur.
Great centipedes are generally feared, but the poison of most of them, although painful, is not toxic enough to be lethal to humans.
Centipedes also use poison as a defense mechanism, which can be deadly for some animal species and cause severe pain and allergies for humans.
Some cave dwellers have no eyes and other kilopods have few to many ocelli. In some species, ocelli are grouped and organized in such a way that they form compound eyes. However, there is no evidence that these compound eyes work more than just detecting light and dark.
A pair of Tomosvary organs are present at the base of the antennae. The few studies on these organs suggest that they detect vibrations, perhaps auditory. The last pair of centipede legs has a sensory function, they are modified to form a pair of anteniform appendages, directed backwards.
What is the habitat of centipedes?
Kilopod habitat is mainly in dark and humid places . Usually they are found under rocks, logs, bark, usually those that are in the process of rotting, rubbish debris and in sewage networks. Most have nocturnal habits and live in the intertidal zone.
They are solitary animals, represented by species that live in hot climates. Around 1,100 species are known worldwide, but estimates are that there are approximately 2,500. For the Neotropical region there are about 200 described species, of which 150 live in Brazil.
Kilopods are distributed in five orders: Geophilomorpha, Scolopendromorpha, Lithobiomorpha, Scutigeromorpha and Craterostigmomorpha (present only in Tasmania and New Zealand).
Centipedes play a decisive role in nature by controlling species of insects on which they feed. Despite the negative view prevailing in the human / kilopod cultural relationship, it is observed that centipedes have been playing significant roles in medicine, religion, literature, mythology, graphic and plastic arts, recreation and food in almost all human societies.
In traditional medical practices, the centipede is a recommended zootherapeutic resource for the treatment of different diseases. In ancient times, centipede liniment was one of the common remedies to treat throat problems.
In Europe, the infusion of small centipedes in wine was a good remedy against jaundice and urine retention. The homeopathic medicine Scolopendra obtained from Asian centipede is recommended for the treatment of sciatica.
In South Korea, Scolopendra is used to cure problems in the joints, legs and feet. They are also recommended for the treatment of stroke, seizures, tetanus, laryngitis, carbuncle, snake bite and bumps.
Some research points out the importance of these animals for the treatment of some diseases. Clinical and pharmacological studies have registered anticonvulsant and antineoplastic effects , since Scolopendra preparations inhibited seizures generated by strychnine and pentylenetetrazole in laboratory animals, as well as inhibited the growth of several neoplastic cells in vitro.
Antifungal effect and good results against diphtheria have also been obtained . The discovery of a new antibiotic should be expected, since females of some species cover the egg mass with a fungicidal secretion.
Centipedes and culture
In Ancient Egypt, the centipede was a symbol of the god Sepa, a funerary god venerated in Heliopolis and invoked against evil animals and the enemies of the gods. The centipede was considered an animal of the land, while the serpent belonged to the sky. It was also a hieroglyph in the pyramid texts.
Mayan culture also worshiped this animal. In Japan, the giant centipede is part of some samurai legends. In Barbados, it is believed that when a centipede crosses someone’s path, it means that the individual has an enemy and therefore the animal must be killed.
It is also customary to believe that conversations about centipedes can encourage them to break into homes.