Published: July 3, 2017

Small Millipedes Impact the Earth in a Big Way

Petra Sierwald, Associate Curator, Negaunee Integrative Research Center

Millipedes are incredibly successful and resilient. They’ve been in the business of vegetable waste management for the past 420 million years. 

Millipedes use their powerful jaws to eat their veggies. After chewing the veggies to bits, this material then passes through the millipede’s digestive system, which is equipped with fungi and nematode worms to assist in digestion. Millipedes are essential for soil health: by releasing processed organic matter at the hind end, they act as decomposers and help return nutrients back into soil.

Today, we know of just over 13,000 described millipede species (you can dig into the list in the online catalog MilliBase). They occur on every continent except today’s Antarctica. Over their long history, millipedes have traveled with the continents, wherever the continents happened to be. Millipedes perform important ecosystem services, especially in today’s deciduous forests, which could drown in their own leaf litter were it not for millipedes to chew the discarded leaves down. Their activities are part of a multi-step decomposition process that helps create a rich and thick humus layer in North American forests. This humus layer acts like a sponge that holds moisture for a long time, to water the trees in time of drought.

So, how have millipedes managed to survive for so long? Over time, they’ve evolved a lot of special features that helped their success. One suite of complex adaptations has led them to be, well, unpleasant—as in, unpleasant to eat. Most millipedes give off foul-smelling and bad-tasting secretions, produced by glands along each side of their bodies. Some of these secretions are cyanide; others are benzoquinones. South American monkeys and Malagasy lemurs pick up millipedes and squeeze them a bit so that the millipedes excrete their nasty chemicals. Rubbing these secretions all over their bodies, the monkeys and lemurs outsmart the mosquitoes, using a natural repellent. But the lemurs and monkeys are also smart enough not to eat these bad-tasting millipedes. In fact, it takes special courage (and special abilities) to eat millipedes. A few animals have succeeded in doing that, but we know very little about who preys on millipedes and how millipede populations are regulated and balanced.

We do know that the millipedes’ adaptations have helped them continue to perform important work over hundreds of millions of years, and we depend on them for their ability to recycle and renew the environment.

Petra Sierwald
Associate Curator

Main Research Interest:

Evolutionary Biology; biodiversity, phylogeny, biogeography and systematics of Arthropoda, especially Arachnida and Myriapoda; morphological evolution, museum collections analyses

Research: Collections-based biodiversity research in Arachnida and Myriapoda, contributing to species discovery and higher level phylogenies, and to the analysis of complex and new morphological characters suites for phylogenetic research as well as to the development of taxonomic tools. Research strategies address the vastly different knowledge-base in Arachnida on one hand and Myriapoda on the other, with nearly all research in integrative and collaborative arrangements (e.g., millipede phylogenomics research grant). Curation and Education:

Specimen and tissue collection building, improvement of collection accessibility (e.g., NSF TCN grant) and stewardship of data, specifically building the first global and fully referenced millipede species database. Research and biodiversity-centered training at various levels (e.g., REU site grants), advising US-based and international graduate students, and outside grant-funded postdoctoral training are important components of my professional portfolio.