Millipedes have two pairs of legs in each segment of their body, whereas centipedes have a pair per segment. That’s how you identify these harmless leaf litter-eating creatures from their more irritating family members. This yellow-striped dark leaf-mulcher, the Anoplodesmus saussurii, is a very efficient converter of leaf to soil, common across the tropics (being reported from Madagascar, Fiji, Singapore, Thailand, Vietnam, the Philippines, Brazil, USA, Martinique), and is said to have an Indian or Sri Lankan origin. Based on colour, it is sometimes mis-identified as the Harpaphe haydeniana, (which is found only in the Pacific coastal region of North America, from Alaska to California) or the Orthomorpha Weberi (which is rare, and has been found only in Bogor, in Java).
Darwin’s last work was his study of the transformation of a landscape by the action of earthworms. This was the founding study of what is now called bioturbation, the perturbing of soils by biological action. Mulching and home recycling of food waste uses earthworms, but gardens with their leaf litter, so useless to most animals, are turned over by millipedes. That’s why these yellow-striped dark leaf-mulchers are so common around gardens and urban areas, as well as in undisturbed ground. They are said to be extremely efficient at breaking down the detritus and recycling it into soil.
I came across statements like this while looking at these papers: “The millipedes belong to class Diplopod, a highly diverse group of terrestrial organisms with over 12,000 described species and an estimated 80, 000 species yet to be described” or “The millipede fauna of India is only poorly known and the records and descriptions are widely scattered in the literature. Indian Fauna of Diplopoda is represented by 11 orders, 20 families, and about 120 genera and 500 species.” I realized that I’m unlikely to ever contribute to any of these counts. But then there is also the fact that “These ancient soil invertebrates have a significant impact on the soil due to burrowing, litter breakdown, and the mixing of organic and inorganic substances in their digestive system which are allocated to different soil layers.” I could study that at home, I thought.
Anoplodesmus saussurii: Length 21–33 mm, width 3,5–4,8 mm, body large and very broad. General colouration of adult individuals is shiny dark brown to black. Ventral part of collum and rounded short paraterga are bright yellow, and legs are light brown. The metaterga are smooth with a deep transverse groove. The male gonopods are of unique shape.Peter Decker and Trudy Tertilt, in Nature in Singapore
I needed to build a small terrarium and populate it with these creatures. I found that you have to be careful while handling them. When disturbed they secrete cyanide; their bright colours warn predators that they are poisonous. You can easily collect tens of them in a spadeful of humus. After copulation (featured photo, three pairs) the female lays several hundreds of eggs. You could study the whole life cycle, and the rate at which these creatures degrade organic matter. I’m so glad to have found something to occupy me after I retire!