Giant African Millipede Achispino spretptus gigus Fact Sheet

Transcription

1 Giant African Millipede Achispino spretptus gigus Fact Sheet Status: Common Distribution: Africa Habitat: Rainforests (under rocks in moist soil and plant matter) Diet: decaying plant matter Length: Up to 12 inches Weight: [Nothing Determinable] Reproduction: The male and female locate one another through the secretion of pheromones. After mating, the female constructs a chamber under ground, which she lines with dung. She can lay up to 2000 eggs inside! In about three weeks the young hatch. At this stage they only have 3 pairs of legs. They add more legs with each molt. Longevity: Up to 7 years General Description: A millipede (name means thousand-foot) has 2 sets of legs per body segment. Unlike centipedes, these animals are harmless, have rounded bodies, and their legs remain under them, instead of protruding from the sides of the segments. Behavior: These nocturnal animals are very docile. To defend themselves, if need be, they will curl up in a ball and secrete a foul smelling liquid. This liquid can be harmful if ingested or it comes in contact with your eyes. Did you know? Millipedes do not actually have a thousand legs - they usually have from (2 sets of legs per body segment) Where can you find them? As pets, in zoos and in the wild 4001 E. Paisano Drive, El Paso, Texas 79905, Phone: , Fax: , elpasozoo@elpasotexas.gov, Status, Distribution, Diet, Length, Longevity, Some of General Description, and Behavior from: Did you know from: Reproduction from:

2 Captive Care and Breeding of the Giant Millipede Scaphiostreptus parilis acuticonus Attems by Stephen W. Bullington Introduction Before I start in about how you can keep and breed this millipede, I need to say something about its scientific name. It's wrong, or at least misleading. Dr. Richard Hoffman did the identification. He's a millipede expert from way back, who's now at the Virginia Museum of Natural History. Anyway, he said the millipede was described under that name in 1914, just before the First World War. It was described from a male taken in N'Yong in the former German colony of Kamerun. This male is deposited in the museum in Vienna, Austria. Whether there are any paratypes is a mystery. Back then no one made distinctions between holotypes, allotypes, and paratypes. This first collection is apparently the only one ever recorded in the literature. According to Hoffman, it's possible there are a few unidentified specimens in museums, but it's not likely. The only ones he'd ever seen didn't come from a museum at all. They were confiscated by the Florida Department of Agriculture from a local pet store. The problem with the name is, that Dr. Hoffman has also seen the type subspecies, S. paralis paralis. He is absolutely certain it is a completely separate species from the critter we're covering here, S. paralis acuticonus. He also is certain that neither species actually belongs in the genus Scaphiostreptus. Further the two species do not fit into any known African genus of millipedes. He is sure that eventually a new genus will be required. Until then, we really have no choice but to use the old name. Like many other large African millipedes, S. paralis acuticonus belongs to the family Spirostreptidae. Needless to say, with only the collecting data for the original specimen(s), there isn't any hard data on either habitat or distribution. But Hoffman thinks it is probably found east and southeast of the Niger Delta, into Cameroon, Gabon, and perhaps even the Republique Centr-africaine. Many other African millipedes have this distribution. It is roughly that of the tall equatorial forest. So how did I come by a poorly known millipede from the heart of Africa that has even the experts grasping for a generic name? Simple. I bought it from Ward's Natural Science Establishment. They were being sold simply as "giant millipedes" and in January 1997 I ordered six. Two of these were obviously different and have long since died. The other four were S. paralis acuticonus. All four were over seven inches long, and the biggest was about eight and a half. If you took a cross section of this fellow in the middle the resulting cut would have

3 about the area of an American nickel. As you can see in the lead photo, these millipedes are also strikingly beautiful, being a deep flat black tone. The glossy sheen in the photograph is from the double flash bracket on the camera. In addition to their beauty I like these millipedes for three reasons. First, they are quite docile and apparently used to handling. Their main line of defense is a passive coil into a tight spiral, as in the photo above. Their back-up defense is the active secretion of a liquid. This liquid comes from glands that are arranged one pair to each segment along the sides of the body. If they are like other large spirostreptids, this liquid, or repugnatorial fluid, probably consists mostly of quinones and hydrochloric acid. As far as humans are concerned, this chemical brew is fairly harmless, although it should never be eaten or applied to the eyes. But it is rarely used, and only if the millipede is dropped, pinched, or otherwise treated very roughly. My particular individuals have never secreted much of anything. Second, I think that with adult supervision these millipedes would be an ideal animal for showing to classes of elementary school kids. Specifically, the kids could even be allowed to handle the millipedes. If the millipede happened to be riled into secreting some fluid, the accompanying adult could simply see to it that the offending child washed his hands thoroughly with soap and water. And third, these millipedes are incredibly easy to raise. This means they can be produced sustainably in large numbers. It also means they have potential both as a lab animal and as a food item. The last may seem far fetched, or at least unexpected, but it isn't. One of the most popular giant scorpions, the Emperor scorpion, is reputed to feed on millipedes in the wild. Who knows, it might even eat S. paralis acuticonus. Emperors might do considerably better in captivity if they ate them there, too. Like all millipedes, S. paralis acuticonus is composed of a large number of apparently similar segments. Most of these segments have a very large, overarching dorsal portion (the tergite) and two small, concealed ventral portions (the sternites). A pair of legs is associated with each sternite. The millipede thus appears to have two sets of legs for each segment. This extra compliment of legs has given the group as a whole the nickname "million leggers." Fig. 3.--S. paralis acuticonus using its mouthparts to groom its legs. Millipedes are much like insects in some respects. Specifically, they have a very insect-like head. This head is provided with a pair of antennae. It is also provided with insect-like mouthparts, notably with a pair of "jaws" or mandibles and with a plate-like lower lip, which goes by the unpronounceable name of gnathochilarium. As in some insects, the millipede uses these mouthparts to groom itself. The millipede head differs from that of most insects in that the compound eyes in the former are very poorly developed. In the millipedes were are covering here they are mere clusters of simple eyes.

4 Captive Care As I said, S. paralis acuticonus is incredibly easy to rear. Until they begin to die of old age, the four original adults were housed for five months along with about young in a single 5.5-gallon aquarium. As of this writing (5 March 1998) only one adult is left, but most of the young are two to three inches long. This aquarium is fitted with a glass top in which two inch-and-a-half holes have been drilled. This bottom of the aquarium is filled to a depth of about 3 inches with damp kiln-dried wood chips. These wood chips are topped with about an inchthick layer of unmilled sphagnum moss. A naturalistic water bowl is one corner has been converted to a food bowl. The top portion of this bowl is removable. In the year I have had these millipedes I have never done one thing either to clean or to replace the substrate. My duties consist entirely of a twice a week routine of replacing the food, cleaning the food bowl, and misting the sphagnum lightly to keep everything damp. I also occasionally add some new sphagnum on top of the old, as after a while it begins to condense because of decomposition. After all this time the substrate resembles black peat, and has a sulfur smell. Although this might seem to be bad husbandry, it is quite the reverse. The young of some millipedes are reputed to be coprophagous, that is, they eat their the dung excreted by their parents. This probably helps the young millipedes in two ways. First, it pre-digests the food, making it easier to swallow (we're talking millipedes here, remember!). Second, it allows bacteria in the gut of the adult millipede to be transferred to the gut of their progeny. This bacterial flora may be responsible for helping digest some of the food (such as cellulose), or producing necessary vitamins. In any event, I think my leaving the millipede dung in the aquarium has been the secret of my success at rearing the young. By the way, I forgot to mention there is quite a bit of this dung. Each time I feed the millipedes I put in from half to an entire cucumber, sliced. A few days later it is gone, or, more accurately, converted into millipede flesh, dung, and a few gases. The biggest portion by far is dung. It comes out of the millipedes in soft, dark turds the size of a gelatin pill capsule. They depositing these turds quite frequently. If you look hard enough, there's a remarkable ecological lesson in this activity. I've had the millipedes for over 60 weeks, and each one of these weeks I have put a large cucumber or two in the aquarium. Sixty cucumbers is more than enough to fill the small aquarium many times over. Yet only a small fraction of this mass, mainly the rinds, ever left the aquarium once it went in. What is left as a solid must still be in there, as compacted dung. This conversion illustrates the oft-made statement that millipedes are one of the earth's primary decomposers, ranking right up there with termites and earthworms. I need to say a bit more about food. I've only fed the millipedes two types of food, namely, the cucumbers I mentioned and very rarely some cut slices of apple. They like the cucumbers better than the apples. They are also fairly finicky about the type of cucumber they will eat. I live on a farm and they won't touch the

5 variety we raise for making pickles. But they love the big cucumbers we buy at the store. I always made sure whatever I put in is thoroughly washed with warm water first, to rinse off any insecticide residues. I also avoid washing with soap. Lastly, everything I put in is sliced. In spite of their size, the millipedes have very weak mouthparts. Their mandibles are blunt and lined with hairs, making them poor tools for cutting and chewing hard material. They cannot chew through the rind on a cucumber or even the skin of an apple to get to the softer tissues inside. This inability to gnaw probably explains their taste in cucumbers as well. The insides of the pickle cucumbers are fairly hard and yellowish. The store-bought jobs have a softer, pasty-white pulp. Even with the softer variety, the millipedes often wait a while before digging in.. This allows the rotting process to soften up the food even more. In addition to food per se, millipedes need lime salts. These salts can be provided using blackboard chalk. Immature millipedes will nibble at pieces placed in with the food. The salts are incorporated into the cuticle or armored skin. They give it its peculiar "tough," almost crustacean quality. I add a few sticks of chalk with every meal. In addition to food and minerals the millipedes need water. They do not get their quota by drinking. At least, I have never seen them drink, and I don't provide them with a water bowl. Instead of drinking, they apparently get their water by "licking" up tiny droplets that bead-up on their tergites. In captivity, these form after I have misted the tank. In nature, they probably form every evening as dew. Much of their water intake may also come from food. Breeding Millipedes can be sexed by looking at the genital openings. These are situated on the third body segment, on the ventral side just behind the second pair of legs. One opening is associated with each leg. You cannot see the openings directly. In the female you will see a pair of plates or sclerites. In the male you will see paired intromittent organs. Before copulation these organs transfer the sperm to the first pair of legs on the seventh segment. These legs then transfer the sperm to the female. When mating, the male and female coil into a tight ball, as in the photo at the beginning of this article. The initiating individual, which I assume is the male, holds onto its partner like a constricting snake would hold onto a mouse. It wraps its anterior body around its mates' body, and bends its head down to lock that of its mate in place. This double grip results in about the first ten segments of both sexes being opposed ventrally. The initiating individual then extrudes a membranous sack from between the seventh and eight sternites. This sack is clearly visible in the photograph. Once the sack is engaged, the pair rest with the body motionless for an indeterminate time. The pair in the photograph stayed in that position for about 20 minutes. They separated when I tried to move them to get a better photograph.

6 It was five months from the time that I observed the first mating to the time I first saw an immature millipede. I did not observe the eggs. Supposedly in spirostreptid millipedes like S. paralis acuticonus the eggs are laid in a walled chamber, which the mother constructs from specially prepared dung. I have no doubt this chamber was present, but it must have been constructed beneath the sphagnum. The millipedes are capable burrowers and constructed a series of tunnels and underground chambers a few days after I put them in the aquarium. The first millipedes I saw were pure white, very small, C-shaped, only 2-3 mm across, and looked for all the world like tiny Japanese beetle grubs. I first saw these baby millipedes in tiny cavities or cells around the base of the naturalistic food bowl, when I was removing the top of the bowl for cleaning. In nature these first-instar millipedes probably form their cells on the underground surfaces of rocks. Unfortunately, I did not preserve any of these neonates for making a permanent microscope slide. At the time I thought there were only three or four, and I wanted them all to live (later I discovered I had more than I knew what to do with). Nor did I take any photos. I was too busy with the consulting work I do for a living. The resemblance I noted to beetle grubs was not accidental. Supposedly the neonates of all millipedes have only a few body rings and three pairs of legs, one to a segment, just like insect larvae. They add rings and legs as they grow. About a week after I first noticed the grub-like first instars, some molted into a multi-legged form more in keeping with that of their parents. These second instars were creamy white, very supple, and very active. If anything, they were even more captivating than their parents, but in entirely different sort of way. To me at least, to watch them was to enter a world of enchantment. With a gliding movement and palpating antennae, they constantly explored the surface of the sphagnum. Their creamy white, spotlessly clean, perfectly dainty bodies seemed in stark contrast to dark trodden surface on which they walked. Over the months these immatures have gotten much larger and their cream color has darkened to successively darker shades of gray. A few are now well over three inches long and correspondingly broad. Eventually I will be taking some photographs of these larger immatures to add to this article. Conclusions S. paralis acuticonus is beautiful, docile, handleable, and very easy to rear in large numbers. It makes an ideal "pet" in every sense of the word, for kids of all ages. It also has the potential to serve as a research animal in entomology labs, and perhaps as a specialized food item for captive rearing large forest scorpions. I have written this article because I think it will make a valuable addition to the panoply of creatures that we as humans have "domesticated." The story of this millipede is also a wonderful object lesson about how private hobbyists can contribute to Science. A few years back this creature was basically unknown,

7 and, for all anyone knew, possibly extinct. Now we know how to rear it in huge numbers, for research, fun, and profit. I find that exciting. Further Reading Cloudsley-Thompson, J. L Spiders, Scorpions, Centipedes and Mites. Pergamon Press, London, xiv pp. (Good popular account of millipede biology concentrating on smaller or pest species from temperate climates; very little on giant tropical Spirostreptidae). Hopkins, S. P. and H. J. Read The Biology of Millipedes. Oxford University Press, xii pp. (Readable, but a bit technical and aimed more at scientists than laymen.)