top of page

MAMMAL NAMES | Finding Moby:

Origins of the Names of Ireland's Sperm Whales & That of the Greatest Literary Incarnation of Their Species, Moby Dick

Illustration of Moby Dick battling Captain Ahab
'From the ship’s bows, nearly all the seamen now hung inactive; hammers, bits of plank, lances, and harpoons, mechanically retained in their hands, just as they had darted from their various employments; all their enchanted eyes intent upon the whale, which from side to side strangely vibrating his predestinating head, sent a broad band of overspreading semicircular foam before him as he rushed. Retribution, swift vengeance, eternal malice were in his whole aspect, and spite of all that mortal man could do, the solid white buttress of his forehead smote the ship’s starboard bow, till men and timbers reeled.’

It is surely through the name Moby Dick, that of the great white whale at the heart of Herman Melville’s eponymous nineteenth century novel, that most of us will have encountered a sperm whale. But though such an encounter on the page may fall short of a true meeting in the real world and leave us in some respects with an unfortunate impression of this cetacean, it can certainly serve as an entertaining introduction to this mighty whale. The passage above alone captures many of the features of this marine goliath: the massive head with a powerful forehead; the surprising speed; the obvious size of a beast big enough to ram a ship. Of course, this also captures the fact that this whale has not just been hunted but is an unrivalled hunter itself, and many of these features are reflected in its many names. This fantastic whale deserves a blog to itself, not least because it is the largest predator in Ireland’s seas today, as well as one of the largest predators ever to live in Irish waters.

After making such a statement it is surely best to begin by seeing just how large the sperm whales are. Well, these whales can reach truly whopping proportions, males being up to 19 metres in length and 63 tonnes in weight, while calves are already around four metres long at birth. With such incredible dimensions we might expect that these whales must be relatives of giants like the humpback whale or blue whale, but in fact they are closer relatives of the dolphins that we met last month.

The whale’s order, Cetacea, is split into two sub-orders, the baleen whales and the toothed whales, and the sperm whales belong to the latter group along with the dolphins and porpoises, although they are by far the largest members of this group. Indeed, they are among the largest toothed predators to ever inhabit the waters around Ireland, rivalling even the giant marine reptiles that terrorised Irish seas during the Age of Dinosaurs.

The sperm whales swimming through Ireland's waters today would be a match even for the mighty marine reptiles which ruled Irish seas during the Age of Dinosaurs

These living oceanic titans are very widespread, with only the killer whales having a wider geographic distribution than them, and it is the largest forms that seem to pass through Irish seas. During their seasonal migrations, larger males cruise through the waters off the western continental shelf, especially in the late summer and autumn, and occasionally even wander into inshore waters a little closer to the island.

If you set out expecting to see a ‘great white whale’ off the coast of Ireland, though, you would very likely come away disappointed. Usually sperm whales are not white but dark grey, although the coloration is paler on the underbelly and around the head. However, on rare occasions they can indeed be completely white, and the author of Moby-Dick, Herman Melville, appears to have modelled the colour of Moby Dick on a real-life albino sperm whale called Mocha Dick that had many battles with whalers in the Pacific in the early nineteenth century, these usually taking place in the waters surrounding Mocha Island off the central coast of Chile.

If in search of a sperm whale, then, it would be best to keep your eyes peeled for a dark grey giant, not a white one. But though there are other massive dark grey whales in Irish waters, such as the humpback whale, sei whale, or fin whale, the sperm whale is very hard to confuse with any of these as it has an extremely distinctive form. For instance, its head is quite square in shape and takes up about a third of its body length. Indeed, it is from this feature that its scientific name, Physeter macrocephalus, is derived, with macrocephalus meaning ‘big head’. Physeter also seems to refer to the head, translating as ‘wind instrument’ or ‘blowpipe’, and so is a reference to the blowhole.

A pod of sperm whales. Note their massive, square-shaped heads and tiny lower jaws

The Irish name for the sperm whale, caisealóid, also appears to refer to a feature in their giant square heads, albeit this time one that resides on the opposite side to the blowhole, in the lower jaw. Caisealóid seems to derive from ‘cachalot’, an alternative name for the sperm whale in English which comes from the archaic French cachalot, meaning ‘tooth’ or ‘big teeth’. And this whale certainly does have impressive gnashers in its lower jaw, each one in males up to 20 centimetres in length and around a kilogram in weight.

The funny thing about these mighty teeth, though, is that they do not appear to be necessary for the sperm whales’ capture of prey, and well-nourished sperm whales have been caught that did not have teeth or even lower jaws! Certainly, the lower jaw is very undersized compared to the rest of the head even when present, being very narrow and slender and virtually disappears into the upper jaw when the mouth is closed.

That the teeth and even the lower jaw are not that important to this colossal marine predator appears to relate to the manner in which it captures its prey. Rather than seizing upon its quarry with its sharp teeth and ripping it to shreds, the sperm whale swallows its prey whole.

And what prey. Although sperm whales will feed on medium- to large-sized fish like bony fish, rays, and smaller sharks, as well as octopus, they also tackle far larger relatives of this mollusc. The skin of sperm whales is often pocked with circular scars that are evidence of mighty struggles with giant squid and the powerful suckers on their impressive arms.

Such giant squid (Architeuthis dux) are found in waters worldwide, and a favourite local hangout of theirs appears to be the Porcupine Bank at the edge of the continental shelf to the west of Ireland. And while the members of this many-limbed race of giants that have been found in Irish waters are smaller than the 18-metre-long females that represent the zenith of this species as regards enormity, they are still gigantic creatures measuring around six metres in length and must not be the easiest of prey even for the colossal sperm whale, especially considering that they are denizens of the deep.

But journeying to such deep waters is something of a speciality of the sperm whales, who possibly dive deeper and longer than any other animal on Earth. Females are incredible divers, capable of diving to depths of 1,000 metres for over an hour, but it is the much larger bulls that make the most jaw-dropping descents. Down, down, down into the black depths of Poseidon’s realm they go, evidence suggesting they can reach as far as 3,200 metres below the surface of the sea.

And how they achieve such fathomless forays into the watery abyss is partly due to an adaptation from which their name ‘sperm whale’ is derived. Sperm whales have a clear, waxy substance in their huge foreheads called spermaceti, meaning ‘whale sperm’, this name arising due to whalers in the past misinterpreting the nature of this cephalic goo. One function of the spermaceti appears to be related to echolocation, serving as a lens to focus sounds, but it also seems to play a role in diving; the modification of this substance helping sperm whales to dive to great depths.

When making a dive, sperm whales cool the spermaceti in their heads, and as it becomes more solid the whale’s density increases, helping it to sink. After going about their business in the depths, then, these whales can aid their climb back to surface waters by pumping more blood through the spermaceti to melt it once again, thus increasing their buoyancy.

Unfortunately, the spermaceti which so enhances their abilities as a hunter has also in the past made them the target of hunters. Although their newborn calves can be vulnerable to predation by killer whales, sperm whales have little to fear from other marine species, and it is a terrestrial species that has learned to hunt on the sea, Homo sapiens, that has proved their true nemesis. From the early 1700s up to the mid-1960s, tens of thousands of sperm whales were caught every year, their spermaceti prized as a fuel for lamps and a lubricating oil, the ambergris in their intestines used in the production of perfumes and cosmetics, and their blubber and meat a valuable food source.

Location of the spermaceti organ from which the sperm whale's English name is derived

For centuries, then, encounters between sperm whales and whalers were extremely frequent, but these head-to-heads did not always go the whalers’ way. And Mocha Dick was not the only sperm whale to inspire Herman Melville’s Moby-Dick, as the ending of the book, which includes the passage quoted at the beginning of this blog, was also influenced by a real-life whale. In this case, it was a sperm whale that rammed, and sank, a whaling ship called the Essex in 1820, leading to a dark scramble for life amongst the survivors, with a number of them subsequently being cannibalised before rescue.

And this ramming of the Essex highlights another feature of the sperm whales that populate Ireland’s waters today. Although these gargantuan sea-dwellers usually cruise around in surface waters at a leisurely speed of around seven to eight kilometres an hour, they are capable of breaking into fearsome sprints, propelling their ferocious bulk through the water for short periods at around 30 kilometres an hour. No wonder such cetacean battering rams could strike fear into the hearts of whalers in times past.

There is something deeply compelling, then, about the size, power, and strength of sperm whales, and Melville’s Moby-Dick seems to capture something visceral about the relationship between Man and Nature. So, it is no wonder that people have returned to the story of Moby-Dick time and time again in the many years since it was first published in 1851, and one of the most notable instances witnessed the arrival of a number of giants with great names on Ireland’s southern coast around a century later.

In 1954, a pod of Hollywood greats, in the form of the director John Huston and the actors Gregory Peck and Orson Welles, made the coastal town of Youghal in Co. Cork their home during the filming of Huston’s 1956 film adaptation of Moby-Dick, with Youghal standing in for the Massachusetts whaling town of New Bedford. And while there, Huston and his film crew were based in Paddy Linehan’s pub in the centre of the town, where no doubt more than a few vessels came under attack. This pub still stands in the town today, but it has since undergone a very suitable name change – it is now known as Moby Dick’s.

like what you've read?

Website Update Blog Boy with microphone PD pbay altered orange background.png

share this post

Please use the icons below the blog text above (or 3-dot icon at top of blog text on mobile) to share directly to Facebook, Twitter, and LinkedIn, or use the rightmost icon to copy the link and share it with people via email, WhatsApp, Viber, etc.


read another one

To read another blog post from the same blog category, simply press return/back on your device. To read one from another blog category, just click on the button below to go to the blog categories section:

Or click this button to go to the All Posts section:


You could contribute greatly to The Evolution of Ireland Project simply by spreading the word about it, or by making a financial contribution of any size in return for a range of rewards.

Doing this is simple – find out how in the Support This Project section below.

bottom of page