apparatus and methods for deheading shrimp using the venturi effect . a shrimp - laden fluid is pumped through a conduit system and lined with one or more venturi tubes . the acceleration of the fluid through the venturis detaches the heads from the shrimp . the cross - sectional areas of the venturis each have a major axis and a shorter minor axis . the major axis is long enough to receive the majority of or all the length of a shrimp and minimize hard collisions with the entrance to the venturi that could damage the shrimp .