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.