  A myth of antiquity is explained with modern science in the context of an
ancient naval battle. A legend was invoked by the admiral Pliny the Elder to
explain the defeat of Antony and Cleopatra against Octavian at the naval battle
of Actium. A fish, called echeneis or remora, is said to have the power to stop
ships or to delay their motion by adhering to the hull. Naturalists have since
studied how the fish sucking-disk with its typical pattern of parallel striae
sticks to its host. Here we show the pattern of the free surface measured in a
towing tank in the wake of an ancient galley is similar to the striae pattern
of the fish. We have measured the bathymetry at the mouth of the Ambracian Gulf
that influenced the physical environment of the battle. The computations
demonstrate the increase of wave resistance of a galley as a function of the
draft to the water depth ratio in shallow water corresponding to the appearance
of a particular wake pattern: the echeneidian free surface pattern.
