Ocular Freezing Avoidance in Antarctic Fish

A series of experiments was undertaken to determine the underlying mechanism of ocular freezing avoidance in a variety of antarctic fish. The three possible mechanisms that were examined include the depression of the freezing point through (1) colligative or (2) non-colligative means or (3) the supercooling of the ocular fluids. The ocular fluids of antarctic fish, like those of most vertebrates, are slightly hypotonic with respect to plasma and contain very low levels of serum proteins. The chief means of ocular freezing avoidance appears to involve supercooling of the ocular fluids. The presence of suitable barriers to prevent ice propagation into the eye has been demonstrated both in vitro and in vivo.