From Francois Duminy
I enjoyed the revelation that sailfish use their bills as swords to slash at their prey (26 April, p 17).
It seems to me that their very large dorsal fin is a lateral stabiliser for the animals’ incredibly fast swordplay.
Could we infer that other billfish, such as marlins and swordfish, also fence with their prey, but don’t need such sails because their bodies are heavier and “taller”, thereby increasing their stability?
Cape Town, South Africa
