March 10th, 2006
the great millipede mystery
Over the past three summers, I’ve happened across the remains of several millipedes which (at least to me), seem to have expired under mysterious circumstances. The species, Sigmoria (Rudiloria) trimaculata trimaculata (Wood), is flat-bodied with segments that resemble some form of armor. Unlike the round-bodied Narceus species, these Sigmoria have far fewer legs and are not so hyperactive and rapid when on the move. I’ve videotaped Sigmoria eating damp moss and their movements are ponderous. While eating, they move their heads side to side, antennae held in a position similar to that of a brahma bull as they slowly chew at soggy moss.
Of the Sigmoria that I’ve found, the dead far outnumber the living. At first, when I found an immobile millipede, my first thought was that it might be in the process of moulting. However, closer inspection soon revealed that most were quite dead, as in the case of the above individual who, when found, was being dragged along by an overly ambitious ant.
Stranger still, most of these millipedes were found hanging over sticks above the ground, or seemed to have died in the midst of walking up a tree or over a rock — in other words, always in a very exposed location (see below). This seems odd to me, as I rarely find living Sigmoria moving in such places. Most that I’ve found have been in damp, mossy, sheltered spots out of direct sunlight.
At this point, I haven’t really got a theory for cause of death. I don’t think the millipedes were killed by larger creatures that regarded them as prey. For one thing, their remains are usually complete and undamaged, with the exception of the odd one which was in the process of being consumed by ants or similar. Also, this species is probably quite unpalatable to most animals as it can release a weak cyanide-type fluid as a form of self-defense. Further, and this adds to the oddness of the situation, on at least a couple of occasions, I’ve found two dead millipedes in very close proximity. Cause of death? For now, that remains unknown.
To view more photos of pedes, visit my millipede gallery on Pbase.
