Swordfish

Why did humans take so long to invent swords? How do swordfish use their swords? Is a swordfish bigger than my whole family? Find out on this episode of species.  

Bibliography: https://docs.google.com/document/d/1zyGukCFXL-CWQKHbDOUnswGq52Hyp4Cbt4WngHQ2wZY/edit?usp=sharing