SCOLOPENDRA: CHARACTERISTICS, HABITAT, FOOD, SPECIES - BIOLOGY - 2025

Scolopendra (Scolopendra) is a genus of chilopod myriapods (Chilopoda class) whose representatives are characterized by presenting a dorsoventrally depressed body, a pair of antennae with 17 to 30 trunks, as well as 21 to 23 pairs of legs, of which the first pair it is modified like fangs to inject venom, called calipers.

They are generally small organisms, although Scolopendra gigantea, the largest species, can exceed 30 cm. They are carnivorous species that hunt their prey at night, while during the day they remain hidden in rock crevices, under the remains of trees, caves, among other hiding places.

Scolopendra gigantea. Taken and edited from: Syrio.

Scolopendras are dioecious, sexually reproductive organisms, with females presenting a single ovary and males having one or more testicles. They do not have copulation and fertilization is indirect. The female lays about 15 eggs, which incubate until hatching as juveniles.

The genus was coined by Linnaeus in 1775 and is worldwide in distribution. It currently has about 100 species, but some researchers maintain that there are still some cryptic species to be identified, which have been masked by the high morphological variability that occurs in the group.

All species are toxic and their venom contains serotonin, histamine, lipids, polysaccharides and proteases, among other bioactive components. In humans, the effects of scolopendra poisoning include cardiac arrhythmia, myocardial ischemia, acute renal failure, and seizures, but it is rarely fatal.

characteristics

Scolopendras have a dorsoventrally depressed body composed of 21 to 23 segments, each provided with a pair of elongated legs arranged on each side of the body and extended so that the body is close to the ground. On the head they present a pair of simple and multi-articulated antennae, generally made up of 17 to 30 joints.

They are mandibulated arthropods, with jaws provided with teeth and setae, and below these appendages two pairs of maxillae are located that also participate in the feeding process.

The legs are multi-articulated and simple, that is to say, composed of a single branch. The first pair of legs on the trunk is modified as large poisonous claws called calipers or poisonous nails. The last pair of legs is sensitive or defensive and longer than the rest, it is never used for movement.

The size varies according to the species and the conditions of the place where it develops. The largest species in Europe, Scolopendra cingulata, can reach 17 cm in length, while the largest scolopendra of the Caribbean islands, and also of the genus, is Scolopendra gigantea and can almost double that length.

Taxonomy

Scolopendras are arthropods located in the subphylum Myriapoda, class Chilopoda, Order Scolopendromorpha, and the family Scolopendridae. The genus Scolopendra was coined by Linnaeus in 1758, but Linnaeus did not designate a type species.

The appointment was made by Pierre André Latreille, who selected Scolopendra forficata for this purpose. However, this species was later reassigned to the genus Lithobius, for this reason, the International Commission for Zoological Nomenclature selected Scolopendra morsitans, also described by Linnaeus in 1758, as a new type species.

The genus currently has about 100 species, most of which are distributed in the Neotropics. For example, in all of tropical Asia there are 16 species of Scolopendra, while only in Mexico 14 species have been reported.

Habitat and distribution

Scolopendras are basically nocturnal organisms, during the day they are hidden under bushes, rocks, leaves, trunks, in rock crevices or they build galleries by digging in the ground. They prefer areas with high relative humidity.

They can inhabit from desert areas to coniferous forests, even in forests with flat trees. The Scolopendra genus is cosmopolitan, with representatives around the world, mainly in the tropics. The only regions where they are absent are the polar ones.

Scolopendra cingulata. Taken and edited from: Eran Finkle עברית: ערן פינקל.

Some species have a very restricted distribution, such as Scolopendra pomacea, which is only known from some states in central Mexico. Others have a wider range of distribution and even some of them, such as S. subspinipes and S. morsitans, are widely distributed around the world.

Feeding

Scolopendras are predators, their main prey are small insects such as butterflies, grasshoppers, beetles, cockroaches and other arthropods such as spiders and scorpions. Snails and earthworms are also part of the diet of some scolopendras.

Larger or more potent venomous species, such as Scolopendra subspinipes mutilans and S. gigantea, can even feed on frogs, lizards, birds, mice, and even some snakes.

According to some authors, to detect the prey they use their antennas. Others, however, maintain that the prey is captured by the last pair of legs, which are heavily armed with thorns and nails and then turn the body to drive the calipers into it and paralyze or kill them.

After the venom is injected, they do not release their prey but instead hold them in place with the second jaws and calipers, and use the jaws in conjunction with the first jaws to manipulate and ingest it.

Reproduction

The scolopendras are organisms of sexual reproduction, with the sexes separated (dioecious or gonochoric) and oviparous with direct development. In other words, a juvenile hatches from the egg with the same characteristics as the adult, but sexually immature and smaller in size.

Females have a single ovary located dorsally with respect to the digestive tract. The oviduct empties into the ventral region of the genital segment. The male can present several testicles also in a dorsal position and which discharge the gametes into a single spermiduct.

Both males and females have gonopods in the genital segment. These gonopods are appendages that intervene in the reproductive process of the species of this genus. Males build a nest with a silk similar to that of spiders where they deposit their spermatophore (packet of sperm).

The female collects the spermatophore and introduces it into her genital opening to the spermatheca. It can be seen in the following video:

Sperm are released when the eggs mature and fertilization occurs.

The female lays 15 or more eggs, over which she exercises parental care until hatching. To protect them, it often curls over them, covering them with its body and legs.

The development is epimorphic, that is, from the eggs hatch some juveniles similar to their parents, with all segments and appendages developed, but their gonads have not yet developed and are much smaller.

Featured species

Scolopendra gigantea

This species is known as the giant scolopendra, being the longest representative of the genus. Although the average of the species is close to 26 cm, some specimens can exceed 30 cm in length.

The giant scolopendras have a coloration that varies between reddish and brown when they are adults, while in the juvenile stage their coloration is dark red to black, with the head region red and proportionally larger than that of the adults.

It is an American species, distributed mainly in the Caribbean islands, from Hispaniola to Trinidad and Jamaica, including the Lesser Antilles and the island of Margarita (Venezuela). In the continental region it is distributed from Mexico to Brazil.

It mainly feeds on other arthropods such as cockroaches, scorpions, crickets, grasshoppers, butterflies, tarantulas, although thanks to its size it can also prey on larger species, including mice and bats.

The giant scolopendra instills a lot of fear, however, its venom, although painful, is very rarely fatal to humans. Despite this, some people have specimens of this species as pets.

Scolopendra cingulata

At 17 cm in length, this is the largest European Scolopendra species. This species has a light brown to greenish-brown color and darker transverse bands, the juvenile organisms are lighter, with the more conspicuous transverse bands and the head and last body segment and its appendages are orange.

It is typical of the Mediterranean countries in areas of medium and low altitude. It feeds mainly on other arthropods and snails. Its habitat is typical of the genus, that is, under stones and logs, among bushes, etc.

Scolopendra polymorpha

Scolopendra polymorpha. Taken and edited from: Marshal Hedin from San Diego.

It receives this name because it is very variable in its coloration and in some bodily characters, for example, the antennas have a number of joints that goes from 7 onwards. Their body size can range from 10 to 18 cm.

It is also called the tiger scolopendra or tiger centipede due to the presence of a dark lateral band on its body. The coloration of the body can vary from brown to orange, while the head can be dark brown, red or orange.

It is an American species, distributed in the southern United States and northern Mexico, generally inhabits desert areas, which is why it is also known as the Sonoran desert centipede. However, it can also inhabit wooded areas.

Scolopendra hardwickei

This species is commonly known by the name of the Hindu tiger scolopendra. It is common in southern India and also inhabits, although in much lower densities, on the islands of Sumatra and Nikobar.

Scolopendra hardwickei stands out for its bright color of alternating dark orange and bright black bands, each band corresponding to an entire body somite. The legs, head and antennae are also dark orange, although the first 6-7 joints of the latter have a lighter hue.

Poison

Scolopendra venom is a highly diverse cocktail of substances with more than 60 families of poisonous proteins and peptides. These substances include serotonin, histamine, lipids, polysaccharides, protease and phospholipase enzymes, cytolysin, and peptides that possess neurotoxic activity.

Scientists have managed to characterize one of the peptides that make up the venom of the Chinese red-headed scolopendras (Scolopendra subspinipes mutilans). This peptide is called in English Ssm Spooky Toxin (SsTx) or Chilling Toxin Ssm. These last initials by the scientific name of the scolopendra, from where it was extracted.

The toxin is relatively small, composed of 53 amino acid residues, and is characterized by being positively charged due to the presence of arginine and lysine at positions 12 and 13, respectively.

Thanks to its positive charge, it actively interferes by associating itself with the negative charges of the potassium channels of the nervous system. As a result, the brain's communication with the heart and respiratory system fails, causing the heart to stop beating and breathing to stop.

The venom can act in fractions of a second and is so powerful that 10 micromoles of the toxin are enough to block potassium channels in a tenth of a second. This allows Scolopendra subspinipes mutilans to attack and prey on organisms up to 15 times their size, such as mice and birds.

Bite

The sting of scolopendras is extremely painful, however, it is rarely fatal for humans. The intensity of pain is proportional to the size of the scolopendra causing the injury. The main risk with this type of sting is anaphylactic shock.

Symptoms of Scolopendra poisoning, in addition to very severe pain radiating from the site of the bite, include inflammation, redness of the skin, inflammation of the lymphatic channels (lymphangitis), and ulcerations and local tissue necrosis may eventually occur.

The pain, and sometimes itching, can last for several weeks. Other symptoms such as vomiting, sweating, headache, cardiac arrhythmia, kidney failure with loss of protein in the urine, as well as seizures, are very rare.

The venom is injected through the calipers. In addition, scolopendras secrete toxins at the bases of the legs, which have very sharp claws and can inject these toxins, which cause inflammation and local irritation.

Treatment for scolopendra poisoning is symptomatic. Doctors recommend immunization against tetanus and cleaning the wound to avoid infection. For pain, they recommend analgesics or hydrocortisone. Non-steroidal anti-inflammatory drugs and antihistamines are also recommended.

Some authors suggest the use of papain, a compound present in papaya that is capable of denaturing the venom.

Applications

Researchers have isolated a bioactive component of Scolopendra subspinipes mutilans that has been shown to lower cholesterol, triglyceride, and low-density lipoprotein levels in laboratory mice, which they believe may help manage some obesity-related problems.

It is also potentially useful for the treatment of diabetes mellitus, due to its ability to maintain blood sugar values ​​at adequate levels.

References

1. W. Siriwut, GD Edgecombe§, C. Sutcharit, P. Tongkerd, S. Panha (2016). A taxonomic review of the centipede genus Scolopendra Linnaeus, 1758 (Scolopendromorpha, Scolopendridae) in mainland Southeast Asia, with description of a new species from Laos. Zookeys.
2. Centipede bite. On Wikipedia. Recovered from: en.wikipedia.org.
3. TL Postma (2009). Neurotoxic Animal Poisons and Venoms. Clinical Neurotoxicology.
4. Scolopendra. On Wikipedia. Recovered from: en.wikipedia.org.
5. J. Molinari, EE Gutiérrez, AA de Ascenção, JM Nassar, A. Arends & RJ Márquez (2005). Predation by giant centipedes, Scolopendra gigantea, on three species of bats in a Venezuelan cave. Caribbean Journal of Science.
6. A. King (2018). Deadly component of centipede venom identified. Recovered from: chemistryworld.com.