Mictyris
Mictyris is a genus of brightly coloured crabs, placed in its own taxonomical family, the Mictyridae. It inhabits the central Indo-West Pacific region. These crabs congregate on mud flats or beaches in groups of a few thousand, and filter sand or mud for microscopic organisms. They congregate during low tide, and bury themselves in the sand during high tide or whenever they are threatened. This is done in wet sand, and they dig in a corkscrew pattern, leaving many small round pellets of sand behind them.
Species
The genus contains eight species:| Image | Scientific name | Distribution |
| Mictyris brevidactylus Stimpson, 1858 | Japan, China, Taiwan, Singapore, and parts of Indonesia | |
| Mictyris darwinensis Unno & Semeniuk, 2011 | Australia | |
| Mictyris guinotae Davie et al., 2010 | Ryukyu Islands of Japan | |
| Mictyris livingstonei McNeill, 1926 | Australia | |
| Mictyris longicarpus Latreille, 1806 | Bay of Bengal to New Caledonia and Australia | |
| Mictyris occidentalis Unno, 2008 | Australia | |
| Mictyris platycheles H. Milne-Edwards, 1852 | Tasmania and Australia | |
| Mictyris thailandensis Davie, Wisespongpand & Shih, 2013 | Thailand |
The predictable behaviour of these crabs has led them to be used in experiments in a form of billiard ball computer.