Why Do We Call Them Sperm Whales?

Kids seem to have rather selectively inquisitive minds, like they are programmed with special mental-detectors for awkward questions that adults dread to be asked. But, really, do we not all have a little child in our head asking “Why are sperm whales called sperm whales?”

Perhaps you are also not sure if you want “Why are sperm whales called sperm whales?” in your Google history. Imagine the personalised ads generated from that! Says the writer who for some inexplicable reason has Star Wars, the Empire Strips Back! ads on their Facebook feed. Well, The answer is not quite as indecently sperm-related as you might think.

Perhaps it is a little biased for a biology student to say this, but one of the best ways to understand an animal is to get a good insider’s view, through dissection! Understandably though, whale carcasses are just not that easy to stumble across these days.

No matter. In 2011, a British television series called Inside Nature’s Giants broadcast a special sperm whale dissection episode which, among many other whale mysteries – like why sperm whales have prehensile penises – enlightens the viewer how these fascinating creatures acquired their spermatic names.

Not surprisingly, sperm whales gained their names from whalers. During the 1800s, whales provided people with many important products. Their large bodies yielded meat that could be used for food. Whalebone – the plastic of the 19th century – was used for products like umbrellas, fishing rods, corsets, crinolines, jewellery and toys like chess pieces and dominoes.

Whalers also discovered that a white waxy substance filled a large amount of a sperm whale’s head. This substance was assumed to be sperm. Hence, ladies and gentlemen, their name, sperm whales!

Of course it is not actually sperm. For one thing, why would a female whale have masses of sperm encapsulated in her noggin? It turns out this sperm fills a huge sac called a spermaceti organ that, amusingly, is found on top of the whale’s ‘melon’ or ‘junk’ – fat tissue used by toothed whales for echolocation. Spermaceti was a useful substance for humans because it made a wonderful smokeless lamp fuel and was also used as a lubricant for industrial machines.

But when spermaceti is still where it should be, snug inside a sperm whale’s head, it serves other fascinating purposes. Spermaceti acts as a buoyancy control mechanism for sperm whales. The whales can heat it with their blood causing the spermaceti to become liquid and therefore less dense, buoying the whales up to ocean surface with ease. When these living submarines wish to dive down into a desired abyss, they simply take in cold water through their right nostril, cooling the spermaceti which then becomes cold and dense and, most importantly, heavy. The sperm whale sinks down like those weighted pool toys.

Sometimes, it is good to listen to that child in your head, because it is often awkward questions that lead to the most interesting answers.

Illustration by Rose Illus