Centipedes ("100 feet" in Latin) are arthropods—members of an invertebrate class that includes insects, spiders, and crustaceans. All centipedes belong to the class Chilopoda, which includes about 3,300 different species. They are found on every continent except Antarctica, and they have the greatest diversity in shape and configuration in warm and tropical environments. Most centipedes are adapted to burrowing and live in soil or leaf litter, under the bark of trees, or beneath stones.

Centipede bodies are made up of six head segments (three of which are mouthparts), a pair of poisonous maxillipeds ("foot jaws"), a variously numbered series of truck-bearing leg segments, and two genital segments. Their heads have two antennae and a varying number of paired compound eyes (called ocelli), though some cave-dwelling species are blind.

Each legged segment is made up of an upper and lower shield covered by a cuticle and separated from the next segment by a flexible membrane. Centipedes periodically shed their cuticles, which allows them to grow. Their body length ranges from 4 to 300 millimeters (0.16–12 inches), with most species measuring between 10 and 100 millimeters (0.4–4 inches).

Beyond these standard centipede characteristics, there are some facts that are more interesting or even surprising. Here are seven of them.

Centipedes Never Have 100 Legs

Though their common name means "100 feet," centipedes can have significantly more or less than 100 legs—but never 100 exactly. Depending on the species, a centipede can have as few as 15 pairs of legs or as many as 191 pairs. However, regardless of the species, centipedes always have an odd number of leg pairs. Therefore, they never have exactly 100 legs.

The Number of a Centipede's Legs Can Change Throughout Its Life

Should a centipede find itself in the grip of a bird or other predator, it can often escape by sacrificing a few legs. The bird is left with a beak full of legs, and the clever centipede makes a fast escape on those that remain. Since centipedes continue to molt as adults, they can usually repair the damage by simply regenerating legs. If you find a centipede with a few legs that are shorter than the others, it is likely in the process of recovering from a predator attack.

Though many centipedes hatch from their eggs with a full complement of leg pairs, certain kinds of Chilopods grow more throughout their lives. For example, stone centipedes (order Lithobiomorpha) and house centipedes (order Scutigeromorpha) start out with as few as 14 legs but add pairs with each successive molt until they reach adulthood. The common house centipede can live as long as five to six years, so that's a lot of legs.

Centipedes Are Carnivorous Hunters

Though some occasionally scavenge a meal, centipedes are primarily hunters. Smaller centipedes catch other invertebrates, including insects, mollusks, annelids, and even other centipedes. The larger tropical species can consume frogs and even small birds. To accomplish this, the centipede usually wraps itself around the prey and waits for the venom to take effect before consuming its meal.

Where does this venom come from? A centipede's first set of legs are venomous fangs, which they use to inject paralyzing venom into prey. These special appendages are known as forcipules and are unique to centipedes. Additionally, large poison claws partially cover the mouthparts of centipedes and form part of the feeding apparatus.

People Keep Centipedes as Pets

It's surprising but true. There are even centipede breeders, though most centipedes sold in the pet trade are wild-caught. The most common centipedes sold for pets and zoological displays come from the Scolopendra genus.

Pet centipedes are kept in terrariums with a large surface area—a minimum of 60 square centimeters (24 inches) for larger species. They require a built substrate of soil and coconut fiber for burrowing, and they can be fed pre-killed crickets, cockroaches, and mealworms weekly or biweekly. They always need a shallow dish of water.

Additionally, centipedes require a minimum humidity of 70%; rainforest species need more. Appropriate ventilation should be provided with a grid cover and small holes on the side of the terrarium, but be sure the holes are small enough that the centipede can't crawl through. Temperate species like it between 20 and 25 degrees Celsius (68–72 Fahrenheit), and tropical species thrive between 25 and 28 degrees Celsius (77–82.4 Fahrenheit).

But be wary—centipedes are aggressive, venomous, and potentially dangerous for humans, especially children. Centipede bites can cause skin damage, bruising, blisters, inflammation, and even gangrene. Therefore, enclosures should be escape-proof; although centipedes can't climb smooth glass or acrylic, don't provide them with a way to climb to reach the lid.

And don't worry if you don't see your pet centipede out during the day—centipedes are night creatures.

Centipedes Are Good Mothers

You probably wouldn't expect a centipede to be a good mother, but a surprising number of them dote on their offspring. Female soil centipedes (Geophilomorpha) and tropical centipedes (Scolopendromorpha) lay an egg mass in an underground burrow. Then, the mother wraps her body around the eggs and remains with them until they hatch, protecting them from harm.

Centipedes Are Fast

With the exception of the slow-moving soil centipedes, which are built to burrow, Chilopods can run fast. A centipede's body is suspended in a cradle of long legs. When those legs start moving, this gives the centipede more maneuverability over and around obstacles as it flees predators or chases prey. The tergites—the dorsal surface of the body segments—may also be modified to keep the body from swaying while in motion. This all results in the centipede being lighting-quick.

Centipedes Prefer Dark and Moist Environments

Arthropods often have a waxy coating on the cuticle to help prevent water loss, but centipedes lack this waterproofing. To make up for this, most centipedes live in dark, moist environments, like under leaf litter or in damp, rotting wood. Those that inhabit deserts or other arid environments often modify their behavior to minimize the risk of dehydration—they may delay activity until seasonal rains arrive, such as entering diapause during the hottest, driest spells.