Illacme plenipes is a millipede found in the central region of the U.S. state of California. It has up to 750 legs, more than any other millipede. It was first seen in 1926, but was not rediscovered until 2005.
Although no known millipede species has one thousand legs, Illacme plenipes comes the closest with one recorded specimen having 750 legs. On average, they have over 600 legs, twice the average for millipede species. Despite having more legs than any other creature on Earth, it is actually quite small, even relative to other millipedes. Females grow to just over an inch; males are slightly smaller and have fewer legs.
The species was first discovered in San Benito County, part of the California Floristic Province, in 1926 by a government scientist. However, the species was not seen again until it was rediscovered almost eighty years later, in November 2005, by Paul Marek, a Ph.D. student at East Carolina University, as he was conducting research on millipede systematics and evolution in San Benito County. Marek published his discovery in the journal Nature.
- Marek, P.; Shear, W.; Bond, J. (2012). "A redescription of the leggiest animal, the millipede Illacme plenipes, with notes on its natural history and biogeography (Diplopoda, Siphonophorida, Siphonorhinidae)". ZooKeys 241 (241): 77–112. doi:10.3897/zookeys.241.3831. PMC 3559107. PMID 23372415.
- O. F. Cook & H. F. Loomis (1928). "Millipedes of the order Colobognatha, with descriptions of six new genera and type species, from Arizona and California". Proceedings of the United States National Museum 72 (18): 1–26, f. 1–6, pls. 1–2.
- "ECU students rediscovers rare millpede". East Carolina University. June 15, 2006. Retrieved August 27, 2010.
- Paul E. Marek and Jason E. Bond (2006). "Biodiversity hotspots: rediscovery of the world's leggiest animal". Nature 441 (7094): 707. doi:10.1038/441707a. PMID 16760967.