Millipede. Image Courtesy Marek, P.; Shear, W.; Bond, J. (2012). Creative Commons SA 3.0. It Has to be a Record -618 legs
Millipedes. Millipedes are elongated with 60 or more legs, with most body segments bearing 2 pair. Some of the larger species have as many as 400 legs. Their bodies can be either cylindrical or flat with short 7 segmented antennae. One of the more spectacular species is a 12-inch African millipede that for years has been sold in pet shops in the United States. This practice was recently discontinued due to governmental regulations. The reason for this intervention in the importation of these creatures was not the millipedes but was due to a small mite that was frequently associated with them. These tiny arthropods or so called feeder mites function to clean the millipedes. It is quite interesting to watch these bigger millipedes move. With almost 400 legs, they need a system to keep from tripping themselves. When a millipede “runs’, it lifts each pair of legs in sequence with a wave-like “progression moving down the body.
The 12-inch African millipedes depicted above was imported from South Africa for years and sold in pet shops throughout much of the United States. Several years ago importation of these beasts was prohibited via the USDA. Reportedly the concern wasn’t that these critters would get loose and become agricultural pests. However, the problem apparently was with small mites that were commonly associated with this millipedes-possible pest? In actuality these mites are what are commonly termed feeder mites. They function to clean the millipedes. That was a little sad as the kids loved the millipedes and they were easy to keep and certainly cheap to feed.
If disturbed, millipedes will typically coil up with their head (most vulnerable part of the body) in the center. This of course protects the most vulnerable parts of their body. There are a group of millipedes called the pill-millipedes which roll up much like a pillbug or so called roly-poly. These occur in many tropical areas with a species from Africa reaching the size of a golf ball.
Top. A rolled up African Millipede. Image Dr. Kaae. Middle. Pill Millipede from Talalaveri Coorg, India. Image Courtesy L. Shyamal CC-BY 2.5. Bottom. Millipede Love. Actually They are Mating. Image Courtesy Muhammad Mahdi Karim GNU Free Documentation `1.5.
Millipedes typically feed on decaying vegetation, but they occasionally become pests on plant parts with ground contact. Most millipedes in the continental United States rarely exceed 3 to 4 inches in length. However, some of the tropical species can reach 1 foot. Sometimes millipedes accompanied by centipedes and sowbugs migrate in great numbers. This is believed to be the result of a heavy population build-up because of extremely favorable environmental conditions followed by drought or some other unfavorable conditions such as removal of breeding sites. Migrations at times have been so heavy as to make it necessary to sprinkle sand on slippery railroad tracks to provide traction for the driving wheels of the trains. In one reported migration, a farmer shoveled several gallons of these critters a day from his front porch for three weeks.
These animals are relatively harmless to humans and do not bite. However, a few species can defend themselves by ejecting irritating fluids a distance of several inches. A Haitian species is reported to discharge its secretion at distances close to a yard. The fluid is irritating and possibly dangerous to the eyes and reportedly is responsible for occasional blindness in chickens and other animals. One of the irritating fluids in some millipedes is hydrogen cyanide, the same chemical once used in the gas chamber. Small amounts are released, and the estimated total is approximately 1% the amount needed to kill a human and 40 % the amount needed to kill a small bird.
Closer to home, an insect dealer at one of our Cal Poly insect Fairs was recently observing a small tropical millipede when it shot a spray of some unknown chemical from a distance of over 2 feet directly into his eye. The results were quite painful and resulted in considerable swelling.
Swollen and Inflamed Eye due to Contact with Millipede Defensive Chemical.
Millipedes grow slowly and some can live for several years. Most species prefer damp habitats and remain hidden during the day under objects. Moisture control is of extreme importance in the control of millipedes.
The Cool Thing about Millipedes Is that They Come in All Colors, Sizes and Shapes. Top Image Courtesy of Gilles San Martin from Namur Belgin CC BY SA 2.0. Left Image Courtesy Marshal Hedin CC BY-SA 2.0. Right Image Courtesy Vanden Spiegel D. Golovatch S Gilles San Marten CC BY-SA 3.0.
Centipedes. Centipedes are elongated, flattened, worm-like animals with 15 or more pair of legs, with each body segment bearing a single pair. The last pair is usually longer and points directly backwards and looks very similar to its elongated antennae. As a result, the head end of many centipedes looks very similar to the tail end. This is advantageous, since a potential predator may grab the wrong end which could result in a painful and potentially fatal mistake-good reason to be left alone! The first pair of legs is modified into a pair of fang-like poison jaws, which are capable of inflicting a painful bite. Smaller centipedes are considered harmless to humans, but the bites from larger species can be quite painful, resulting in local swelling. This can debilitate an adult human for a few days. Some of the tropical species are quite large and are greatly feared by humans.
One of the most well-known of these critters is a giant that lives in caves in South America and can reach a length of 18 inches. This powerful beast hunts mice, bats and other relatively large critters. Once seized with its venomous poison jaws, captured bats are said to die in as little as 30 seconds. Although probably not capable of killing a human, villagers in Venezuela claim that the bite of one of these giants did kill a child. I do know of an individual that was" playing" with one of these creatures (not smart) and was bitten. He was sick for a few days with a severely swollen hand.
At times, it almost appears that these and other arthropods have the ability to think. Of course this is quite doubtful, but they have been well-equipped to react instinctively (almost appearing intelligently) too many circumstances. We recently watched a large Vietnamese centipede catch and feed on a cricket. Once caught, the centipede immediately cut off the cricket’s legs, thus removing its ability to escape. Thinking that this was an accident, we fed it another cricket with the same results. Taking this impromptu experiment a step further, we fed a cricket to a different centipede with the same result-thought the first one might have been smarter-oops! They don't think.
Giant South American Centipede. Image Courtesy Katka Nemčoková CC BY-SA BY SA 3.0
Underside of Large Vietnamese Centipede Head Showing Poison Jaws. Image Dr. Kaae.
The authors recently documented a case of a bite from a large species of Arizona centipede. In this situation, a homeowner bent over to drink from a water hose. Unfortunately, a 12-inch centipede had recently occupied the hose, and when the water was turned on, the centipede appeared and bit the individual on the tongue. His tongue and mouth swelled considerably and he was in pain for several days.
These organisms are nocturnal and remain hidden during the day in protected locations such as under loose bark, rotting logs, rocks and in tunnels and voids in the soil. Centipedes are fast moving, and most are predaceous on spiders, insects and other small animals. The diet of the larger species is not limited to insects or other arthropods. They certainly are large and strong enough to subdue small snakes, mice, lizards and even birds. They can easily be distinguished from millipedes by how quickly they move. Because millipedes feed on plant tissue, there is no need for agility and they move quite slowly. You don’t need to be fast to run down a leaf. Generally, plant-feeding arthropods are slow while predators are relatively fast.
The common house centipede is about 1 inch long, grayish-tan in color with long antennae and extremely long legs. As their name implies, these creatures are commonly found running over walls and ceilings in homes. They are harmless and could be considered beneficial as they feed on cockroaches, houseflies, moths, spiders and other pests found in and around the home. However, I am sure most homeowners would not consider them an added benefit to the home, especially the Thai species shown below.
Top. Common U.S. House Centipede. Dr. Kaae. Bottom. Thai House Centipede-Image Courtesy John Moore.
With the exception of the common house centipede, these creatures are not as commonly found in the home as millipedes. Of course part of the reason for this is that their outdoor populations never reach that of millipedes. However, if a centipede does occur indoors, it can be somewhat stressful. One evening (on a Hawaiian trip) one of our visitors was washing dishes and a 7-inch centipede appeared from under the dishwashers (apparently a fairly common occurrence in Hawaii). She came running from the kitchen screaming centipede, centipede! According to her, she couldn’t sleep that night. A note of importance-never try to transport living centipedes on a commercial airline. After capturing the centipede, I decided it would make a nice addition to our insect zoo at Cal Poly. I neatly packed it away in a small container in my luggage. Of course on getting home, the critter was dead. I guess it gets pretty cold in the cargo area of planes.
On a later occasion, I decided to bring back several giant millipedes (12-inch beauties) I had collected in Malaysia. Keeping in mind that they wouldn’t make it in the cargo area, I decided to carry them in my carry-on luggage. While waiting for the plane to begin loading, I decided to check and see how they were doing—big mistake! One of the stewardesses saw them out of the corner of her eye and freaked. She first thought they were snakes and called security. After convincing all involved that they weren’t snakes, I still couldn’t convince anyone that they were harmless. I was subsequently escorted from the airport to release the monsters back into nature-almost missed that flight. I guess it could have been worse. Luckily for us, the movie “Snakes on a Plane” had not yet been released.
Not learning from those experiences, I later transported a large variety of living critters (scorpions, walking sticks, millipedes, tarantulas, etc.) on Alaskan Airlines up to Oregon for a presentation. I was going to a presentation at the Oregon Pest Control Association. I had no problem getting them on the plane on the way up but was stopped by security on the way back. Major alert-you would have thought I was some kind of terrorist. After convincing the authorities that these critters were not going to kill anyone, and that I wasn’t totally nuts, the additional problem was that it was prohibitive to bring living animals of any kind on a plane. I think the exceptions were dogs and cats in cargo and goldfish. They again wanted me to take the specimens out of the airport and release them. After some fast taking and actually doing a short presentation on these arthropods to the airline officials, they let me put them in cargo after they triple boxed them. Again, we almost missed that flight as well.
By the way, when I got to the Pest Control Association and asked what time was my hour presentation, their answer was I was supposed to talk the whole day--6 hours to 300 people. After a few minutes of panic, I decided to cover a good deal of the material in this class-already knew most of it. They seemed to love it.
We once stopped at a roadside stand in Thailand to buy some dried-roasted caterpillars for an afternoon snack (when in Rome do as the Thai-or something like that)) and were offered a quart bottle of home-brewed whiskey. However, instead of having a worm in the bottle as doe’s Mexican tequila, there was a 14-inch pickled centipede. Drinking the whiskey enhanced by centipede was said to give the consumer great strength or at least make the consumer think he or she had great strength until they sobered up. This belief is apparently common in several of the South-East Asian countries. By the way, the worm in the bottom of the tequila bottle is a caterpillar that feeds on the century plant from which tequila is derived.
As you might expect, these arthropods as a source of human food in some countries (MM-centipedes on a stick!)
Centipedes on a Stick. Image Courtesy Denise Chan from Hong Kong, China CC BY-SA 2.0
Crustaceans. This is a very large group of arthropods that occupy diverse habitats, but the majority occurs in fresh and salt water. The more familiar forms (and better tasting) include the crabs, lobsters and shrimp. While these forms are beyond the scope of this text, there are a few common terrestrial crustaceans that we encounter in our daily life--the sowbugs and pillbugs. Both were introduced from Europe and are now distributed throughout the United States and are two of the common larger backyard arthropods. Although these critters have several minor structural differences, one easy way to distinguish one from the other is that pillbugs, as their name implies, are capable of rolling up into a tight pill-shaped ball and the sowbugs are not. Both types possess 7 pair of legs and have a fairly short life cycle consisting of 2 or 3 generations per year. Each female has approximately 50 young which can be found on the underside of the female.
Sowbugs (larger specimens) and Pillbugs. Image Dr. Kaae.
Being crustaceans, sowbugs and pillbugs are not well adapted for a terrestrial way of life. Unlike insects, they lack a waxy layer on the outside of their exoskeleton; this functions to reduce water evaporation from the body. Similarly, the external openings of their breathing system are not fitted with valve-like structures (spiracles in insects) which can be used to close off the system when not in use. This lack of spiracles results in an additional source of water loss from the inside of their body. Dehydration or the loss of water from an arthropod's body is a continuous problem. Because these creatures are relatively small, they have a rather large surface-area-to-body volume ratio (e.g., large area to lose water from and relatively small area to store it internally). In order to prevent dehydration, sowbugs and pillbugs remain hidden during the day in moist situations such as leaf litter, under rocks and logs and forage for food at night. It is common to find large numbers huddled together in order to reduce their surface area and thus conserve moisture.
Sowbugs and pillbugs chiefly feed on decaying organic matter such as rotting leaves and twigs, dead animals and even feces. On occasion, they cause minor damage to plant roots, seedlings and ripe fruit in contact with the ground. In cases where they become pests, their presence can be reduced by removing breeding and hiding sites.
Interestingly enough there is a video of an individual holding 2 giant Crustaceans that belong to the same group as the sowbugs and pillbugs (namely Isopods). It is actually amazing that sowbugs and pillbugs are quite similar to and are related to these “giant” Isopods”, especially considering where both are typically found and the extremely difference in size. The giant isopod can grow to a length of over 16 inches, which makes it one of the largest members of the crustacean family. Like its terrestrial cousin the pillbug, the giant isopod's body is protected by a hard shell that is divided into segments
These giants are of minor interest to commercial fisheries because they are caught and scavenged beyond marketability before they are recovered. The few specimens caught in the Americas and Japan with baited traps are sometimes seen in public aquariums.
These creatures are a good example of deep-sea gigantism (like giant squid). Sowbugs and pillbugs and other "typical" isopods are less than an inch in length. Adults of “supergiant" species can reach a maximum weight and length. Like some pillbugs, they also possess the ability to curl up into a "ball", where only the tough shell is exposed. This provides protection from predators trying to strike at the more vulnerable underside and head. Their large eyes are compound with nearly 4,000 facets and spaced far apart on the head. As with sowbugs, they bear 2 pairs of antennae and 7 pairs of legs.
Giant isopods are important scavengers in the deep-sea benthic environment; they are mainly found ranging from the gloomy sublittoral zone at a depth of 560 ft to the pitch darkness of the bathypelagic zone at 7,020 feet. At these depths pressures are extremely high and temperatures are very low.[ A few species from this genus have been reported from shallower depths, notably B. miyarei between 2 and 919 feet, the poorly known B. decemspinosus between 230 and 260 feet and B. doederleini as shallow as 330 ft.