Notes on feeding, locomotor activity rhythms and orientation in the pygmy mole cricket Afrotridactylus cf. usambaricus in Kenya (Orthoptera: Tridactyloidea)

Immature individuals of Afrotridactylus cf. usambaricus (Sjostedt, 1910) were recorded on a marine sandy beach probably feeding on bacteria, microalgae and mesopsammic organisms. The larvae of this pygmy mole cricket probably obtain these organisms by manipulating grains of sand with their buccal apparatus during the excavation of tunnels close to the surface of the sand. This occurs in daytime during the ebb tide while direct migration to the sea is in progress. Therefore, the migration occurs according to a diurnal-tidal rhythm having been detected only in correspondence with the low diurnal tides. This rhythmic activity remains in phase with the diurnal-tidal periodicity even far from the sea, in a confined environment. Individuals tested in a transparent Plexiglas bowl are able to assume and maintain the sea-land direction of the beach constant throughout the day in the absence of the landscape vision.