 Since the heat transfer coefficient depends on an animal's body shape, tunas increased their body size, adopted a fusiform shape, and their internal tissue arrangement is based on different thermal conductances.Southern bluefin tunas often migrate vertically through the water column in search of their preferred temperature, and they spend time in cooler waters seeking prey.Some have hypothesized that they take refuge in warmer areas of water fronts and eddies after these foraging periods, but others suggest that these migrations are only associated with the aggregation of prey.