Centipedes: Chilopoda

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CENTIPEDES: Chilopoda

SCOLOPENDER (Scolopendra morsitans): SPECIES ACCOUNTS
HOUSE CENTIPEDE (Scutigera coleoptrata): SPECIES ACCOUNTS

PHYSICAL CHARACTERISTICS

Adult centipedes vary in length from 0.15 to 11.8 inches (4 to 300 millimeters). Most species are completely yellowish or brownish, but a few species are brightly colored with distinctive bands on their bodies and different colored legs and antennae (an-TEH-nee), or sense organs. These bold colors and patterns may serve as warning colors to potential predators (PREH-duh-ters), or animals that hunt other animals for food. The head is flat or dome-shaped. The antennae are long and slender with fourteen to more than one hundred segments. Centipedes are bristling with tiny hairlike structures that are used for touch and smell. The eyes, if present, vary considerably. They may have one or more simple eyes, or eyes with one lens, on either side of the head, or a pair of compound eyes, or eyes with multiple lenses. The mouthparts are made up of three pairs of structures. The jaws help cut up food, while the remaining mouthparts help move food to the jaws.

Mature centipedes are long and, depending on species, have anywhere from fifteen to 191 pairs of legs, for a total of thirty to 382 legs. Adults always have an odd number of leg pairs, with one pair on each body segment. Centipedes are the only animals that have fanglike legs used to inject venom. All the legs are similar in length and appearance, except for the first and last pair. Located on the side of the head, the first pair of legs contains poison glands. They inject venom through an opening at the base of each fanglike claw. The last pair is often long and thick and is sometimes pincherlike. These legs are used for grasping or defense. The remaining legs are used for walking, running, or digging.

GEOGRAPHIC RANGE

Centipedes are found on all continents except Antarctica. A few species have become widespread, accidentally carried to other parts of the world with plants or soil.

HABITAT

Centipedes are found in all kinds of habitats, from sea level to high mountain peaks. A few species prefer to live in caves. Some individual species are found in a wide variety of situations under bark, in leaf litter, or under rocks.

DIET

All centipedes are predators. They feed on soft-bodied insects, spiders, other centipedes, and worms. Larger species will attack small mice, frogs, toads, birds, lizards, and snakes. Animals are killed by venom injected by the fangs, then grasped by the fangs and the first several pairs of walking legs. A few species may eat plant materials if they cannot find animal prey.

BEHAVIOR AND REPRODUCTION

Most centipedes are active at night. During the day they seek shelter under objects on the ground, inside logs and stumps, or in animal burrows. During the hot dry weather they will usually bury themselves deep in the soil. They are not territorial and move about the environment in search of food and mates.

Centipedes live alone until they are ready to mate or when they are raising their young. When they do meet, they are often very aggressive toward one another and will sometimes eat the other. Some species living along the seashore hunt in packs. Several individuals will feed together on the same animal, usually a barnacle or beach hopper.

When threatened, centipedes protect themselves by running away or biting. Others whip their bodies about or spread their hind legs wide in a threatening manner. Some species fool predators by having markings that make them look as if they have two heads. Others release bad smelling and tasting chemicals from glands on their undersides. In one group of centipedes, these chemicals actually glow in the dark. A few centipedes produce glue that hardens within seconds when exposed to air. This sticky stuff can tangle up the legs of even the largest insect predators.

Most species must mate to reproduce. The male usually places a sperm packet in a web on the ground. He then coaxes the female to the web by tapping her back legs with his antennae. This courtship may last for hours. Eventually the rear of her body comes into contact with the web and she takes the packet into her reproductive organs. A few kinds of centipedes are capable of parthenogenesis (PAR-thuh-no-JEH-nuh-sihs), where the young develop from unfertilized eggs. Only females are produced by this method of reproduction.

Some species of centipedes lay their eggs one at a time. In other species the female digs out chambers in rotten wood or soil and lays up to eighty or more eggs all at once. She wraps her body around her eggs and cleans them constantly so funguses, molds, or hungry predators do not harm them. Of these species some will eventually camouflage the eggs with bits of soil and abandon them. Others will remain with their eggs, even until after they hatch. They are unable to hunt and remain with their mother until after their next molt, or shedding of their hard outer coverings or exoskeletons.

Young centipedes resemble small adults. However, depending on the species, they may not hatch with their full number of legs. Additional pairs of legs and body segments are added as they molt. For example, hatchlings of house centipedes have only four pairs of legs, while the adults have fifteen. Stone centipedes hatch with six to eight pairs of legs, while the adults have fifteen. In other groups of species, such as the earth-loving centipedes and scolopenders, hatchlings come into the world with all the legs they will ever have. All centipedes molt several times before reaching maturity in a matter of months or years.

CONSERVING WATER IN THE DESERT

The exoskeletons of insects are coated with a waxy layer that keeps them from drying out, but centipedes don't have this waxy layer. Without their bodies to help them, desert-dwelling centipede species depend instead on their behavior to prevent water loss. They come out only at night when the air is cooler and wetter, and they spend their days hiding in the cool and moist shelters of animal burrows or beneath rocks.

CENTIPEDES AND PEOPLE

All centipedes are venomous, but smaller species are either unable to pierce human skin, or the effects of their bites are no worse than a bee sting. However, larger species are capable of delivering a very painful bite. Children and elderly people or those suffering allergic reactions may need to seek medical attention. The severity of a centipede bite varies with species and may produce moderate to severe pain for several hours or days, and well as localized swelling, discoloration, and numbness. Many people believe that the legs of larger centipedes are also capable of delivering venom, but this is not true. Inflamed punctures or scratches as a result of a centipede walking on human skin are most likely due to bacterial infection. There have been very few human deaths from centipede bites.

Large species are sold as pets and are frequently used as display animals in insect zoos. Only one species is thought to be of any agricultural importance and feeds on roots. Centipedes do not cause or spread disease. Most species are of little consequence to humans or their activities.

CONSERVATION STATUS

Only one species of centipede is listed by the World Conservation Union (IUCN). The Serpent Island centipede (Scolopendra abnormis) from the island of Mauritius off the east coast of Africa is listed as Vulnerable, or facing a high risk of extinction in the wild.

Most centipede species are distributed over several continents. But a few apparently have smaller ranges and are known only from single localities. At least one species known only from the Galápagos Islands has not been seen in many years and may be extinct, or no longer alive. The introduction of exotic mammals and snakes has threatened or wiped out many species of island-dwelling animals around the world, including centipedes.

SCOLOPENDER (Scolopendra morsitans): SPECIES ACCOUNTS

Physical characteristics: Adult scolopenders measure up to 5.1 inches (130 millimeters), with the females usually larger. They are variable in color, with the head and body yellowish or brown with darker bands. Each side of the head has a small cluster of four simple eyes. The antennae have seventeen to twenty-three segments. The body has twenty-one pairs of legs.

Geographic range: This species is found throughout the tropics and other warm regions, including Mexico, Central America, the Caribbean, much of Africa, Madagascar, South and East Asia, and Australia, with a few records in tropical South America.

Habitat: The scolopender's habitat varies; they are found anywhere from desert to rainforest.

Diet: They eat spiders, mites, flies, beetles, ants, termites, cockroaches, and other centipedes. Captive individuals will attack small frogs and toads.

Behavior and reproduction: Scolopenders hunt at night and spend their days in leaf litter, under logs, or beneath loose bark. When threatened they can run fast or burrow quickly in leaf litter. They are active throughout most of the year in the warmer parts of their range.

Males deposit a bean-shaped sperm packet measuring 0.01 inches (2.5 millimeters) onto a web. Females dig brood chambers in soil under rocks and lay twenty-six to eighty-six greenish yellow eggs. In Nigeria, the young reach adulthood within a year, with two generations produced each year.

Scolopenders and people: This species may bite if threatened or carelessly handled.

Conservation status: This species is not considered endangered or threatened. ∎

HOUSE CENTIPEDE (Scutigera coleoptrata): SPECIES ACCOUNTS

Physical characteristics: Adult house centipedes measure up to 1.2 inches (35 millimeters) in length. They are yellow or brown with three purplish or bluish bands along the length of the body. They have large compound eyes on each side of the head. The antennae are very long and threadlike with five hundred to six hundred segments. Adults have fifteen pairs of long slender legs that keep the body well above the ground when they are on the move. The last pair of legs are the longest with those of females twice as long as the body.

Geographic range: This species is native to southern Europe, North Africa, and the Near East.

They are widely distributed in North America and South Africa. Populations with limited distributions have been found in Britain, northern Europe, Australia, Argentina, Uruguay, tropical Africa, and Taiwan.

Habitat: House centipedes are found in a variety of habitats under wood, in trash, or inside caves. They are often found in homes, especially in places where there is moisture, such as tubs, basins, and basements.

Diet: They eat silverfish, flies, cockroaches, moths, spiders, and other house centipedes.

Behavior and reproduction: House centipedes are usually active day and night and run quickly when threatened. They can run at speeds up to 16 inches (400 millimeters) per second.

Males and females court one another by forming a circle and tapping each other with their antennae. The male eventually deposits a lemon-shaped sperm packet. He guides the female to it, and she removes the sperm from the packet. The eggs are 0.05 inches (1.25 millimeters) long. The female holds a single egg between her reproductive structures, covers it with dirt, and then places it in a crack in the soil. The breeding season lasts about two months. During this time she will lay about four eggs per day. Hatchlings start with four pairs of legs. With each molt the total number of legs increases to five, seven, nine, eleven, and thirteen pairs. There are five more molts after they have all 15 pairs of legs. Adults live nearly three years in captivity.

House centipedes and people: House centipedes eat insects that are considered to be household pests, such as flies and cockroaches. They are delicate animals, and it is unlikely that their fangs can puncture human skin.

Conservation status: This species is not considered endangered or threatened. ∎