The effect of size and temperature on the frequency of limb beat of Temora longicornis Müller (Crustacea : Copepoda)

Copepods normally swim by rhythmically beating the cephalic limbs, so records of antennal movements represent their activity. The limb beat rate of Temora longicornis Müller was determined in relation to several factors. There was an inverse relationship between swimming rate and body size, and activity increased with environmental temperature up to 20–25°C. Copepods readily acclimated, as those kept at 15°C were less active than those kept at 5°C. The summer population was also less active in the low temperature range, but swimming reached a higher rate at higher temperatures than were tolerated by the winter population. No difference in rate of limb beat was found between similar sized males and females over a wide range of temperatures.