Foraging behavior of the predaceous cladoceran, Leptodora kindti, and escape responses of their prey

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Abstract
Using silhouette video photography we have made the first quantitative observations of foraging behavior in Leptodora kindti , a predaceous cladoceran (Haplopoda). Leptodora swims with a mean velocity of 13.4±4.0 mm s −1 and initiates an attack only upon direct contact with potential prey. The attack sequence is as follows: Leptodora swims randomly through the water column with all five pairs of thorac appendages spread to form a ‘feeding basket’ and, seemingly by chance, encounters prey. Shortly after prey make contact with any part of Leptodora's body (usually ventral), the abdomen is rapidly pulled forward, clamping itself under the feeding basket so that the telson closes it at the posterior end. The duration of this movement is always the same and we conclude that it is an indiscriminate reflex. If the prey is encountered anywhere but a short distance directly in front and slightly below the Leptodora , it is not captured. The speed of copepod escape responses effectively allows them to avoid contact with the predator. Daphnia's escape response, particularly that of juveniles, is slower and leaves them far more susceptible to Leptodora predation.