TwoDiaptomus minutus graze on the algae suspended in the vessel (125 mL). They both swim in horizontally and at a constant speed (see Feeding Currents). However, their paths will cross; they are on a collision course.
Instead of executing an escape reaction, both realize that the other is a conspecific and they execute short hops to avoid each other. The awareness of the existence of the other is due to the hydrodynamic interaction between the two copepods and the subsequent mechanoreception, as revealed by a numerical study using computational fluid dynamics.
The footprints were made visible using the Schlieren technique (Strickler & Hwang 1999; see Publications). More on footprints in Yen & Strickler 1996. Both animals are 1 mm in total length. The algae are visible in the original video and can be tracked as in Feeding Currents.
This clip is short section from a 2-hour long observation videotaped on analog Hi8. The clip was digitized from the video using Firewire and a SONY A/D converter. In ADOBE Premiere we cut it to size and saved it as an AVI file.