Field of Science

The Sad, Sad Story of Physeter


Original drawing of the sperm whale stranded near Berkhey, the Netherlands, in 1598. Reproduction from Husson & Holthuis (1974).


In yesterday's post on the sperm whales, I alluded to the long and reprehensible debate over the name of the great sperm whale Physeter macrocephalus. Reprehensible because for at least the last hundred years there has been absolutely no disagreement over the nature of the animal concerned; the conflict has purely been concerned with what to call it.

When Linnaeus discussed the genus Physeter in the 1758 Systema Naturae, he referred to four species: P. macrocephalus, P. catodon, P. tursio and P. microps. Most authors now treat these names as synonyms of the great sperm whale*. Normally, when two or more names are available for the one species, the oldest name automatically becomes the correct one. However, because Linnaeus' 1758 publication is the official starting point for zoological nomenclature, none of these names count as the oldest. In such a case, the general rule is that the first person to treat the names as synonymous and pick one of them to be the correct name establishes which has priority (the principle of the First Reviser).

*Physeter tursio and P. microps were both described as having high dorsal fins, something the great sperm whale completely lacks, leading to considerable confusion over the identity of the animals concerned. Modern authors tend to assume they were based on distorted or mistaken accounts of ordinary sperm whales; this is not really a satisfactory explanation, but the true identity will probably never be establishable (killer or pilot whales seem not entirely unlikely to me), and there would be little to be gained from trying.

During the 19th Century, most authors knew the great sperm whale as Physeter macrocephalus while the name P. catodon was less often referred to (and sometimes thought to refer to something like the beluga or pilot whale). It wasn't until the beginning of the 20th Century that Oldfield Thomas (1911) asserted the synonymy of the species and selected P. catodon as the correct name. However, in 1938 Hilbrand Boschma noted that Murray had treated the names as synonymous in 1866 and selected P. macrocephalus, pre-dating Thomas' selection. This was countered in 1966 by Philip Hershkovitz who claimed that Murray's selection was invalid.

The most detailed discussion of the matter was by Husson & Holthuis (1974) who discussed each of the records cited by Linnaeus for the names Physeter catodon and P. macrocephalus, selecting a lectotype for the former and a neotype for the latter that confirmed both as sperm whales. They also established that Blasius had treated the names as synonyms in 1857 and selected P. macrocephalus as the valid name, meaning that P. macrocephalus had priority even if Murray was disqualified as an authority.

However, the validity of Physeter catodon was again championed by Schevill (1986) on the basis that P. macrocephalus was supposedly invalid from the get-go. Linnaeus had distinguished the two species on the basis that P. macrocephalus supposedly had its blowhole on its neck while P. catodon had it at the front of the head; the correct position in the sperm whale is, of course, the latter. Schevill claimed that Husson & Holthuis' examination of the earlier records to correct Linnaeus' description was invalid as the concept of type specimens did not exist in Linnaeus' time, making the printed description the only judge of the species identity. Because the description of P. macrocephalus did not agree with a real sperm whale, it could not be used as the valid name.

As pointed out by Holthuis (1987), Schevill's latter argument was simply wrong. If the original author did not explicitly nominate a type specimen for a new species, then all specimens considered in the original description automatically become the type series*. To claim that the concept of types is inapplicable to Linnaeus is to ignore a fundamental aspect of the nature of the Systema Naturae, which did not spring ex nihilo but was in many places an index to the work of earlier naturalists, tying their descriptions into Linnaeus' new nomenclatural system. In the case of the sperm whale, Linnaeus was mislead by the faulty descriptions provided by others (Linnaeus himself had never seen a sperm whale). Examination of these earlier records allows the error to be recognised. Husson & Holthuis (1974) chose as lectotype of P. macrocephalus a specimen stranded in the Netherlands in 1598; while the specimen has not been preserved anywhere, illustrations of it leave no doubt that it was a sperm whale.

*Though it is true that the type specimen did not exist as a formal concept in 1758, it was not long afterwards that naturalists were finding it useful to examine earlier authors' specimens to determine their intention. Exactly when the type concept became formalised, I'm not sure.

So, in summary, both P. catodon and P. macrocephalus are available names for the great sperm whale; Blasius as First Reviser established the priority of the latter in 1857. The correct name for the great sperm whale is therefore Physeter macrocephalus.

REFERENCES

Holthuis, L. B. 1987. The scientific name of the sperm whale. Marine Mammal Science 3 (1): 87-88 (reply by W. E. Schevill, pp. 89-90).

Husson, A. M., & L. B. Holthuis. 1974. Physeter macrocephalus Linnaeus, 1758, the valid name for the sperm whale. Zoologische Mededelingen 48 (19): 205-217, pl. 1-3.

Schevill, W. E. 1986. The International Code of Zoological Nomenclature and a paradigm: the name Physeter catodon Linnaeus 1758. Marine Mammal Science 2 (2): 153-157.

27 comments:

  1. It's a rather interesting way of climbing up the whale's back that they're using in that picture...

    I noticed that such a highly influential source as Wilson & Reeder's Mammal Species of the World (Third edition) uses catodon rather than macrocephalus because the former name has 'line priority'. But there is no such thing as 'line priority', right?

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  2. Correct - line priority has no significance under the ICZN. Though he didn't explicitly say so, I suspect that Thomas' use of Physeter catodon was also due to line priority (Thomas' paper was a discussion of the status of each of Linnaeus' mammal names, listed [naturally enough] in the order they appeared in Systema Naturae; at the end of the discussion of P. catodon, he simply said that the following species [P. macrocephalu] should be regarded as a synonym).

    As for the climbing method - it was hardly much use to the whale any more, was it?

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  3. It seems somewhat perverse of Oldfield Thomas to select catodon if macrocephalus had been the more commonly used for a century or so. Did he give a reason?

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  4. I like stories like this. They make it very clear how useful having an ICZN is for clearing disputes. "Line priority", huh, never heard that one before.

    But yes, it's obvious that Physeter macrocephalus is the valid name, regardless of it's position in the Systema Naturae, regardless of its /description/, because the first reviser chose that name in 1857 and not P. catodon.


    A thought: If Von Linne didn't designate types in Systema Naturae, then he wouldn't be de facto the type specimen, so who is the human type specimen?

    ~Kai

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  5. There isn't really a type specimen for Homo sapiens, I'd say. But the ICZN specifies that a neotype (new type specimen) should only be designated if necessary to establish the identity of a species. Neotype designations made simply to fill a gap are invalid (that's why Bakker's attempt to make Edward Drinker Cope the type specimen doesn't count). Because there's never been any question over what Homo sapiens refers to, there's never been any justification for establishing a neotype for it.

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  6. It occurs to me that you could perhaps argue that every member of Homo sapiens alive in 1758 qualifies as a member of the type series. At least, those who might have been reading Systema Naturae do.

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  7. So this was the real reason for this week's quiz? You needed a legitimate reason to post a cetacean porn wood-cut. LOL

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  8. Stearn designated Linnaeus as the type specimen:

    Stearn, W. T. (1959). The background of Linnaeus's contributions to the nomenclature and methods of systematic biology. Systematic Zoology 8:4–22.

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  9. "Because there's never been any question over what Homo sapiens refers to...."

    You are such a neontologist. ;)

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  10. @Mike: You want to go dig him up?

    ~Kai

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  11. Actually, I think he's in a crypt (in the Uppsala cathedral). But he has plenty of living descendants, anyway.

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  12. Incidentally, the recent findings suggesting that 1-4% of the genome of non-Subsaharans is inherited from Neandertals makes this an interesting case. If Neandertals are considered a species, then the type specimen of Homo sapiens is from a hybrid population....

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  13. Should that hybrid with Neanderthals have its own name? Homo X exafricensis. Or should it be named like a horticultural variety as it was man-made? Homo X "Lagar Velho".

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  14. Has anyone considered the possibility that there *were* in fact several species of Physeter within relatively recent history, all but one of which were hunted to extinction in the industrial whaling era?

    They could have been separated by diet like the arguably-actually-different-species populations of orcas, which would explain stories of sperm whales eating large vertebrate prey, despite modern-day evidence being that they eat almost entirely squid. There are ~200 year old sperm whale mandibles in existence that, if they belonged to animals with the same proportions as those currently living, would have been 50% or so *longer* than the probable maximum size of living sperm whales (which would probably put them in the same weight class as blue whales - a scary thought...). I think it would not be unreasonable for those to be regarded as representing a distinct species.

    There are also records of sightings of "high-finned" sperm whales, of a similar size to living sperm whales but with a dorsal fin similar in proportional size to, but thinner and straighter than, those of large delphinids. If this was a distinct species, presumably it could justifiably occupy one of Linnaeus's unused names...

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  15. @Icarus: While I'm not in a position to have an opinion one way or the other, the idea does excite the imagination.

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  16. Mike: You are such a neontologist.

    Sure, there's been disagreement over the extent of H. sapiens, but that's a different issue. No-one has expressed any doubt that the central focus of the name was modern humans (more specifically, modern Europeans, as some of Linnaeus' successors recognised separate subspecies for separate races).

    Pat: The ICZN doesn't allow for hybrid names in the way that the ICBN does. However, there are indications that hybridisation may be a more significant factor in animal speciation than often assumed.

    Icarus: The possibility of recently extinct sperm whale species is definitely there, but unfortunately it simply lacks strong evidence at present. I believe Cuvier is supposed to have reviewed all the non-standard sperm whale records up to his time and dismissed them as erroneous or fanciful accounts of normal sperm whales, but even then some other authors accused him of being over-zealous in his dismissals.

    I did read over a couple of records of 'long-finned cachalots' while looking up material for this post (try a Google Scholar search for "Physeter tursio"); the ones I found mostly specified animals from twenty to thirty feet in length, much smaller than the known sperm whale. This, and their reported observation in groups, is why I suspect that they may have been pilot whales or killer whales rather than sperm whales (are there any known examples of melanistic killer whales?). Some 19th Century authors seem to have themselves identified the high-finned Physeter species as pilot whales (Gray's 1850 Catalogue of the British Museum mammal collection goes so far as the use Physeter for the "blackfish", referring the sperm whales to the genus Catodon). None of the accounts of "high-finned cachalots" I saw provided enough detail to eliminate any known species (nor, conversely, was there enough to conclusively identify any known species). As I noted in the post, there would be little to be gained from demonstrating such an identification of the high-finned cachalots, though; the only effect would be to unsettle well-established names for these taxa in favour of an older and nearly-forgotten name.

    It is worth remembering when reviewing 18th Century and early 19th Century treatments of whales that many of them relied on briefly-observed animals seen from some distance; actual specimens were usually only available on the rare occasion that a whale became stranded somewhere. This was how such fundamental errors could appear such as Linnaeus' misplacement of the sperm whale's blowhole; alternatively, it was not uncommon for more than one species of whale to be confused and their characteristics conflated (the original account that Linnaeus cited for Physeter catodon, for instance, seems to attribute observations on live pilot whales to a specimen of a juvenile sperm whale). Many cetacean species names rest on rather unsteady foundations into which it is probably best not to enquire too closely. It wasn't until the heyday of whaling in the late 19th Century and early 20th Century that researchers gained access to good numbers of specimens and were able to stabilise whale taxonomy to a certain degree.

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  17. Christopher:

    "It occurs to me that you could perhaps argue that every member of Homo sapiens alive in 1758 qualifies as a member of the type series. At least, those who might have been reading Systema Naturae do."

    If we're only to choose one individual as the type specimen, and if Linnaeus himself in ineligible, how about Lamarck?

    Icarus:

    "stories of sperm whales eating large vertebrate prey"

    Hmm. There is a chapter in Jules Verne's novel 20,000 Leagues Under the Sea (which was first published in 1869), where the Nautilus encounters baleen whales in Antarctic waters. The baleen whales are attacked by a pod of sperm whales, and Captain Nemo, who refers to them as "cruel and evil-doing animals", then attacks the sperm whales by using the Nautilus itself as a weapon.

    I had always thought that the account of the sperm whales' behaviour in that chapter was only evidence of Verne's insufficient knowledge of cetology. Icarus' comment suggests that perhaps Verne didn't _entirely_ pull it out of his butt, after all.

    Christopher:

    "other authors accused [Cuvier] of being over-zealous in his dismissals"

    I'm reminded of the occasion when he was shown one of the iguanodontian teeth that Gideon Mantell sent him for identification in 1821; Cuvier dismissed it as having belonged to a rhinoceros.

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  18. Sperm whales are known for being extremely aggressive when threatened or injured; witness the numerous accounts of ships being sunk or damaged after being rammed by them (such as the sinking of the Pequod that's supposed to have inspired Moby Dick). Early mariners may well have assumed (incorrectly) that such an aggressive animal was an equally vicious hunter of other animals.

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  19. Oh, and Linnaeus isn't invalid as a type specimen for our species. The selection of him as such (whatever its current validity - as a lectotype designation, it probably would be valid) would probably be the most reasonable course of action.

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  20. This may yet be the longest comment thread for a CoO post to date...

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  21. Since - inevitably - Moby Dick got a mention in this thread, and since we're on the subject of whale names, it might be worth noting that in the days of whaling, there really were sperm whale bulls that were given individual names by whalers because of their particular aggressiveness. E.J. Slijper, in his classic book Whales (1965) lists such whales as 'Timor Tim', 'New Zealand Jack' and 'Newfoundland Tom', among others.

    "Linnaeus isn't invalid as a type specimen for our species. The selection of him as such (whatever its current validity - as a lectotype designation, it probably would be valid) would probably be the most reasonable course of action."

    But isn't there any potential conflict of interest? I mean, he did pretty much invent the whole system himself...

    "This may yet be the longest comment thread for a CoO post to date..."

    Don't jinx it, man!

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  22. Dartian wrote:
    But isn't there any potential conflict of interest? I mean, he did pretty much invent the whole system himself.

    You can hardly have a CoI in a matter raised after your death.

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  23. Andreas:

    "You can hardly have a CoI in a matter raised after your death."

    I know, but to me, making Linnaeus the type specimen of Homo sapiens would feel almost like giving a Nobel Prize to Alfred Nobel himself...

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  24. Mike:
    However, there are indications that hybridisation may be a more significant factor in animal speciation than often assumed.

    What do you mean? Interesting!

    Dartian:
    I know, but to me, making Linnaeus the type specimen of Homo sapiens would feel almost like giving a Nobel Prize to Alfred Nobel himself..

    Well, Madame Tussaud has her own wax figure.

    Once heard about someone proposing Raquel Welch for the human holotype (probably jokingly). I like that one better.

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  25. Ooops, that wasn't Mike, but Christopher. Sorry.

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