Aquatic food is diverse in size, shape, location, motility, chemical and mechanical properties (Nikolsky, 1963) as are adaptations in fish to capture and process food. Unlike mammals, fish have no claws, so food collection is performed entirely by the oropharyngeal apparatus. In some, mainly predatory, fish the mouth is specialised for fast and voluminous suction. In others, mainly planktivorous fish, prey capture proceeds by overswimming, and suction plays a minor role (van Leeuwen & Muller, 1984; Sibbing, 1991). The complex of muscles, bones and ligaments composing the suction-pressure pump of the respiratory apparatus (cf. Ballintijn, 1969) eventually performs a whole range of diversified feeding actions. By accurate timing of volume changes in the oral, buccal, pharyngeal and opercular cavities and by differential operation of the oral and opercular valves, carp can perform as many as ten stereotyped patterns of movement, each serving a particular role in food processing (Sibbing, Osse & Terlouw, 1986; and see Fig. 1). These patterns are: (1) particulate intake or (2) gulping for intake, (3) rinsing, (4) spitting or (5) selective retention for sorting food from non-food, (6) transport, (7) loading, (8) crushing, (9) grinding and (10) deglutition or swallowing. In addition, size-selective retention of small food particles (sieving) is effected by the branchial sieve (Zander, 1906; Hoogenboezem et al., 1990), if such particles are abundant. Whereas size, location and motility of food are crucial factors for capture strategies, taste, degree of mixture with non-food and size are determinants in sorting out food from non-food (Sibbing et al., 1986). But how do fish cope with the highly varied mechanical properties of food?