Sinister Centipedes
Robert Gale Breene III
Artesia, New Mexico USA

From Forum Vol. 6, No. 6

A curious article recently appeared (British Tarantula Soc. J. 1997. 13(1): 22-24) causing an extreme occurrence of eyebrow raising on the part of many readers. Throughout the article, statements that can only be classified as wild speculation were apparently offered up as fact. Some of these, like the one where the author claimed centipedes had two powerfully stinging tails that injected venom, were admitted to be false in the following BTS Journal issue.

Despite the later corrections and toning down, the intent of the article was seemingly not to inform, but to terrorize readers. And talk about anthropomorphizing, good heavens! This is fine if you tell your audience what you're up to somewhere in the article, but this author apparently forgot.

One sentence really blasted up my credibility red warning flags. It read; "These are majestic animals, but are as dangerous as they are beautiful and should only be kept by the experienced entomologist." What?!? Did the guy think he was writing for an audience composed of crickets? I didn't know they could read.

Since I are a triple Aggie (joke, not bad editing) with a B.S. and Ph.D. in entomology, I quickly noticed the author's sly irony. Entomologists study insects. People who study centipedes are called myriapodologists (as are those studying millipedes, pauropods, and symphylans). The author insinuated that he was an entomologist, meaning that he shouldn't be allowed to keep them either if he knew what he was talking about.

The article was chock full of hilarious misstatements falsely making centipedes out to be really evil creatures. The only positive aspect centipedes had in the article was their high suitability as candidates for morbid fascination. I'm jealous. This is great stuff and I can't resist writing some myself.

It was a dark and stormy night. The sinister centipede slithered up from the deepest bowels of hell into the dark corner of the little girl's bedroom. She was sound asleep, the evil Scolopendra noted, but the girl was not on tonight's fiendish activity list.

The cat was.

A flawless example of a Siamese feline, the new mother cat had given birth to five tiny kittens just the day before. Tragically, four of the cuddly kittens were stillborn, with only a single precious one surviving.

With deep, diabolical thoughts firing across a synapse or two, the centipede stalked toward the pillow by the side of the girl's bed where the mother cat lay innocently sleeping. Her kitten lay asleep on her soft belly. The only sound the horrible creature made was a slight hissing as some of its razor sharp claws brushed across the fibers in the rug. It reached the sleeping cats.

Digging its last four pairs of legs into the carpet with malice, the centipede began to lift its head up, up, and over the felines. One, two, three feet it hung, swaying back and forth slightly, above its unsuspecting victims.

Clacking its venom injectors together in hatred, the looming centipede aimed at the mother cat's neck and struck like a mad cobra. Its aim held true. The mother cat's carotid artery was violently pierced and over an ounce of deadly venom coursed into the wound, killing the defenseless animal instantly.

The evil centipede casually grasped the now mewling kitten and sauntered back toward its den of iniquity for a leisurely meal.

It had enough to eat for several days, so a dark plan of what to do next for amusement began glowing red hot in its menacing mind. Its barbarous jaws spread in a smile of evil anticipation.

Tomorrow the girl.

Okay. Disregard all the above. Fun as it might be, the ATS won't exaggerate, mislead, or lie to readers, at least not without telling them about it first. Below is what is known about centipedes without all the subjective anthropocentric rhetoric.

In earlier taxonomic literature, all the myriapods were placed together in a single class, the Myriapoda. Currently, they are split into four classes: The Symphyla (from the Greek, meaning growing together), Pauropoda (pauro = small, poda = foot or appendage), Diplopoda (millipedes, diplo = two, here indicating that each leg-bearing segment appears to have two pairs of legs; in reality, each apparent segment consists of two fused segments), and the Chilopoda (centipedes, chilo = lip, here referring to the front pair of legs being modified into a venom-dispensing jaw-like appendage).

Over 3,000 species world-wide are contained in the four orders of Chilopoda. They can have from as few as 15 to as many as 173 pairs of legs depending upon species. Oddly, regardless of how many pairs of legs they have, the number is never an even one.

The stone centipedes, order Lithobiomorpha (litho = stone, bio = life, morpha = form) are smaller-sized centipedes, from less than a quarter inch to nearly two inches in length. They have short legs (adults with 15 pairs), are usually brown, and live as the name implies under stones, logs, bark or in comparable habitats. They are not often encountered by those not looking for them.

The snail centipedes, Geophilomorpha (geo = earth, philo = loving) are often yellow or whitish in color, and have 29 or more pairs of short legs. They occur largely in the soil or in decaying logs. Most are tiny, but some species may reach four inches or so in length.

The house centipedes, Scutigeromorpha (scuti = shield, gero = bear or carry), have long, thin legs and antennae. In some, the last pair of legs is as long, or longer than the antennae, and is thought to function much like a rear pair of antenna. Although found under logs or debris, some species often get into houses where they hunt insect and spider prey. One species, Scutigera coleptrata (L.), is common in houses throughout the eastern US and Canada. It is harmless to humans.

The order capturing the most interest from biologists, collectors and phobiaphiliacs (a word I just coined to indicate people who love to be terrified of something; seems we've been running into a lot of that lately) comprises the tropical centipedes, Scolopendromorpha (scolopendra = centipede). The legs are thickened and short compared to the house centipedes. The largest of the centipedes occur in this order with one tropical species reported reaching nearly a foot and a half in length. Certain US species can reach eight inches or more in length. Coloration varies tremendously. One tropical species sports a jet black body with yellow legs and head. Others have red bodies with orange legs and head. Many sport green or yellow markings.

Centipedes are very active (usually at night), aggressive predators that prey upon insects, spiders, worms, snails and other small animals of the right size for them to handle. Some of the larger ones may feed on small lizards or even baby mice. Many others feed on decaying plant material or are scavengers on a variety of materials.

Centipedes that catch prey do so by seizing it with their first pair of legs, called prehensors, and inject it with venom from connected internal glands. This first pair of legs looks like insect mandibles, and the tarsi (feet) are evolved into fang-like processes at the end of the structure. There has been controversy on what to call the "fang" part of the legs. Since spiders have the venom-injecting (although not all spiders have venom) hardened tip ends of their chelicerae labeled as fangs, I see no problem in calling the analogous portions of a centipede's adapted front pair of legs, fangs. After all, there are many terms being bandied about out there labeling various arthropod parts, or behavior, or development that are extremely confusing, with many downright wrong. "Fangs" pretty much gets the point across whether you are talking about spiders, rattlesnakes, or centipedes.

Other centipede defenses include the spiny hind legs (that can pinch in some) and repugnatorial glands, but their main defense is the secretive ways they use to remain out of sight from predators. Many insect-eating birds apparently regard them as distasteful and ignore them.

A number of centipede species also have repugnatorial glands (from the word repugnant) that emit either noxious or sticky secretions. The former secretion repels attackers and the latter can entangle some predators, like ants, thwarting their attack. The sharp claws on the legs of some Scolopendra centipedes can pierce skin. If disturbed, the centipede may begin to drop noxious material from the repugnatorial glands onto its legs as it runs. This may enter human tissue through the wounds made by the claws and leave the infamous trail of swollen skin in its wake.

Centipedes have a pair of antennae and although many do not have eyes, the ones that do have two patches of simple eyes (ommatidia, or ocelli) that may loosely resemble the compound eyes of insects. The centipede heart is a tube that runs most of the length of the body pushing blood toward the head in the typical arthropod arrangement. Breathing is accomplished as with most arthropods with air tubes (tracheae) running throughout the body from spiracles (air hole openings) near the base of the legs and directly to the tissues. The blood is not used for respiration.

Some scutigeromorphs are unusual in that external middorsal spiracles branch into highly fibrous air tubes (tubules) that surround the heart. These tubules saturate the blood with air that is then drawn into the heart. This adaptation along with differences in hemolymph chemistry allow the blood to be used for respiration in this case.

Males produce a spermatophore (sperm packet) that is transferred to the female either directly or by using a platform of threads he builds and from which he maneuvers the female into accepting the attached spermatophore. Other centipede reproductive strategies generally include the male's leaving a spermatophore somewhere the female is likely to find it.

Eggs are laid in the ground after being coated by the mother with a moist fluid that contains fungicides in some species. Others lay eggs under bark, and some will stay and guard the eggs until they hatch. Unlike millipedes, many species hatch from the egg with all the appendages they are ever going to have. Others sprout additional legs at each molt until adulthood.

Many centipedes are adapted for running rapidly over a variety of surfaces. Some species have more than 300 legs, but even if they only had 30, that's still a respectable number of appendages to keep track of, let alone have them all going in the right direction at the right time. Centipedes have developed a few tricks to keep things running smoothly.

First of all, the segments are joined by a pliable membrane-like connective tissue that can bend and give to different stresses. As they run, they stretch and increase the distance between the legs, lessening the chance of a trip that may start an impressive, perhaps even comical domino effect. Another tripping safeguard includes having each pair of legs on individual segments a little longer than the pair in front of it. Finally, the legs on each segment are geared to be in the opposite phase of each other while running.

With all pieces of the puzzle in place, the centipede run is usually initiated at the pair of legs closest to the head and goes toward the tail in a wave-like motion. Each pair of legs will be doing the same thing as the pair in front, just a little bit later. To increase speed, the length of the leg strokes is shortened so each leg cycle takes less time.

Just how fast can centipedes go? Most are not very quick, but some with the longest and fewest number of legs can zip along at up to 20 inches per second, a speed way too fast for many easily disturbed people.

Centipedes are highly susceptible to water loss for two reasons. The first; they don't possess the ability to close their respiratory spiracles, and water can be easily lost through them. The second; they aren't equipped with the external waxy cuticle that helps prevent water loss through the exoskeleton, as are insects and other arthropods. This makes one wonder why they do so well in the arid southwestern US. It could be their behavior ensures they can find a way to a humid place after a night's foraging. Perhaps they are limited to areas where water is more consistently available.

Most centipedes are found in moist, dark places and that is probably the key to successfully keeping them in captivity. Although many Scolopendra individuals have done well on vermiculite with a water dish constantly available, this probably won't do in the long run. An immature that will need to molt or a breeding pair will most likely require a different habitat. Probably the best captive situation would include a couple of inches or more of sterilized potting or top soil, a water dish constantly kept filled, and some flat rocks to burrow beneath. Good ventilation is probably not important, but some misting may be required. As has been pointed out, centipedes are escape artists. Many are quite strong and can push off heavy cage tops to get away. Make sure you choose a cage that makes escape impossible.

Food in captivity is similar to most tarantulas. Crickets, mealworms, moths, a variety of other insects, and pinkies, if the centipede is large enough.

Much has been alleged on the toxicity of centipede venom, but very little material on the subject has made its way into the scientific literature. As with tarantulas, this vast lack of medical reports on them more than likely indicates they are not medically significant. Like tarantulas, their perceived repulsive appearance by most people is probably the reason they are widely viewed as somehow dangerous and toxic. We do know that some of the larger centipedes, especially in tropical areas, can administer a painful stab, but none are known to be dangerous. All we can say for sure on the subject is that some can cause a painful bite, but that's absolutely all.

Who should keep centipedes? Hell, that's none of our business.

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