A CINEMATOGRAPHIC COMPARISON OF BEHAVIOR BY THE CALANOID COPEPOD CENTROPAGES-HAMATUS LILLJEBORG - TETHERED VERSUS FREE-SWIMMING ANIMALS

Many previous cinematographic studies of copepod behavior have used an imals tethered to dog or cat hairs to keep them in focus. We compared behavior of tethered and free-swimming specimens of the calanoid copep od Centropages hamatus Lilljeborg using cinematographic methods. Preci se quantification was made of the time allocated to four modes of beha vior: slow-swim (movement of feeding appendages only), break (no appen dages moving), fast-swim (posteriorally-directed movement of first ant ennae and pereiopods), and groom (brushing of first antennae through f eeding appendages). Ten copepods each were used for tethered and free- swimming filming. Under both experimental regimes, copepods spent < 1 % of total amount of time in fast-swimming and grooming behavior. Most of the time (50.7-95.5%) animals were on break. The rest of the time (3.8-48.9%) animals were in the slow-swimming mode, moving only feedin g appendages. There were no significant differences between tethered a nd free-swimming animals in mean time allocations to slow-swimming and break behavioral modes. However, individual variability of tethered a nimals was higher than that of free-swimming ones. We conclude that, w hile mean time allocation to slow-swimming and break behaviors were si milar between free-swimming and tethered animals, the variability betw een tethered individuals is a factor to be considered when designing e xperiments.