Outstanding structural features related to habits of life in the chydorid cladoceran Eurycercus lamellatus are described. Crawling is as important as swimming in this deposit-feeding species. The nature of the food, its collection and subsequent manipulation, are described. Both cephalic and trunk appendages are involved in this process. Their structure and mode of action are described and illustrated in detail. Many hitherto unknown structural features are described and the functional significance of these and other morphological peculiarities is explained.