Sperm whales live in a world of sound. Sunlight only penetrates the top couple of hundred metres of ocean. Underneath, it’s permanent darkness. Sperm whales spend more than half their lives at depths of 500m or more, so vision isn’t particularly useful when hunting. The whale’s species name, macrocephalus, means “big head”. Bit rude, but - to be fair - their head is around a third of their body length. A large part of this real estate is occupied by the junk, a mass of oil-saturated fatty tissue, which acts as a component of their sound production and bio-sonar system. That has no direct relevance to the story. I just wanted to point out that they have a lot of junk in their trunk. Anyway, the whales use this organ to make extremely loud ‘clicks’, the loudest noise produced by any animal. Scientists even put forward a ‘biological big bang hypothesis’, suggesting that the whales’ powerful clicks could be used to stun their prey.