The recent discussion of Caperea's skeletal morphology (Caperea = Pygmy right whale) inspired Joy Reidenberg to send these photos of a Caperea skeleton, taken in New Zealand and used here with her permission.
In this view of the whale's thoracic region (we're standing beneath the whale, looking up into its ribcage), you can see that the transverse processes (the wing-shaped structures that project from both sides of each vertebra) are proportionally huge: so big that many of them overlap. The dorsal ends of the ribs - the parts of the ribs that contact the transverse processes - look strangely small and narrow by comparison, and also seem to have really loose connections with the transverse processes. Compare this with the ribcage of a North Atlantic right whale Eubalaena glacialis...
Here, you can see that the transverse processes are, proportionally, much smaller and don't come close to overlapping. The rib heads also look much larger in comparison with the transverse processes, and there are obvious big facets on the transverse processes for the rib heads. And, sorry that the ribcage isn't the main focus of the photo: when I took it I was more interested in the hyoid apparatus and sternum. The photo was taken in the NHM, London. The next photo takes us back to Caperea: now we're looking at the posterior part of the ribcage and the proximal part of the tail. Again, the enormous size of the transverse processes and their overlapping nature should be striking. You can also see the relictual pelvis and the more proximal of the haemal arches, or chevron bones. As we saw last time, the ribs have a peculiar flattened shape.
Again, compare this with the more normal condition present in the balaenid Eubalaena glacialis...
As is normal for a whale - and indeed for a tetrapod - the ribs here are sub-cylindrical, with shafts that are either rounded or oval in cross-section. The flattened ribs of Caperea are really, really weird: as I said last time, it's been suggested that these ribs might somehow function as armour, that they might stiffen the body*, or that they might be something to do with the enlarged laryngeal sac. More study is needed - very little is known of this whale (a real shame given its peculiar anatomy). As it happens, I learnt yesterday that Emily Buchholtz has just published a paper in which she discusses the peculiar rib shape and transverse process anatomy of this whale (Buchholtz 2010). However, her paper is mostly concerned with the reduction in tail length and increase in thorax length, and also in the fact that Caperea's first rib seems to be a 'composite ontogenetic fusion product' representing both the first and second thoracic ribs (weird fused first ribs - located somewhere round about the cervico-thoracic junction - are present in various baleen whales and sometimes incorporate a supernumery cervical rib).
* The idea that Caperea might be particularly stiff-bodied seems paradoxically inconsistent with the fact that extensive flexing of the whole body during swimming has been reported (Ross et al. 1975).
Finally, here's a close-up of Caperea's proximal caudal region. Note again the relictual pelvis and haemal arches. I don't know whether they're correctly positioned...
While I'm here, it's worth saying a few other things about Caperea. Textbooks always used to include Caperea in the right whale family Balaenidae, but its distinctive anatomy has led some authors to give it its own 'family', Neobalaenidae Gray, 1874. While some phylogenetic studies find Neobalaenidae and Balaenidae to be sister-taxa (e.g., Deméré et al. 2005, Steeman 2007) (in which case, the name Balaenidae might still be used for the Caperea + (Balaena + Eubalaena) clade*, as per Bouetel & Muizon (2006)), others find Neobalaenidae to be closer to Balaenopteridae (the rorquals and humpbacks) (e.g., Saski et al. 2005).
* Most authors have used Balaenoidea for this clade.
Unlike balaenids proper, Caperea has a dorsal fin, is proportionally slender and has a small head ('only' 25% of total length, compared to c. 40% in Balaena) [the adjacent image is a famous photo, taken in 1967 in Plattenberg Bay, South Africa. Until fairly recently it was the only photo showing a live Pygmy right whale]. The first specimens recognised by science were collected between 1839 and 1843 when HMS Erebus and Terror toured the world; three baleen plates collected in Western Australia by Mr J. Warwick were studied by J. E. Gray. Recognising them as unusual because of their small size and near-white colour, Gray based the new species Balaena marginata Gray, 1846 on these remains. A complete skull from New Zealand, possessing the same kind of baleen and obviously belonging to the same species, was described by Gray in 1870 and he now regarded this animal as special enough for its own genus: Neobalaena (proof that lack of originality is nothing new in devising new generic names). However, Gray had earlier given the name Caperea antipodarum Gray, 1864 to an isolated tympanic bone from New Zealand, and this proved to belong to the same animal. Accordingly, the animal is properly known as Caperea marginata today. This brief potted history is based on Hershkovitz (1966) and Watson (1981). The animal seems to be a Southern Hemisphere specialist, with all sightings and strandings coming from Argentina, Namibia, South Africa, Australia and New Zealand.
Many people know that, among the living whales of the world, a few beaked whale species were named for isolated skulls and other such remains; the fact that one of the baleen whales was also originally named for fragments is less widely recognised.
Many thanks to Joy Reidenberg for supplying the Caperea photos, and to Bobby Boessenecker for alerting me to Buchholtz (2010). For previous Tet Zoo articles on baleen whales, see...
- A 6 ton model, and a baby that puts on 90 kg a day: rorquals part I
- From cigar to elongated, bloated tadpole: rorquals part II
- Lunging is expensive, jaws can be noisy, and what's with the asymmetry? Rorquals part III
- The newest whales
- Inside Nature's Giants part II: whale guts and hindlimbs ahoy
- When GREY WHALES - you know, from the PACIFIC OCEAN - crossed the Atlantic
- Pouches, pockets and sacs in the heads, necks and chests of mammals, part III: baleen whales
Refs - -
Bouetel, V. & Muizon, C. de 2006. The anatomy and relationships of Piscobalaena nana (Cetacea, Mysticeti), a Cetotheriidae s.s. from the early Pliocene of Peru. Geodiversitas 28, 319-395.
Buchholtz, E. 2010. Vertebral and rib anatomy in Caperea marginata: implications for evolutionary patterning of the mammalian vertebral column. Marine Mammal Science 10.1111/j.1748-7692.2010.00411.x
Deméré, T. A., Berta, A. & McGowen, M. R. 2005. The taxonomic and evolutionary history of fossil and modern balaenopterid mysticetes. Journal of Mammalian Evolution 12, 99-143.
Hershkovitz, P. 1966. Catalog of living whales. Smithsonian Insitution United States National Museum, Bulletin 246, 1-259.
Ross, G. J. B., Best, P. B. & Donnelly, B. G. 1975. New records of the pygmy right whale (Caperea marginata) from South Africa, with comments on distribution, migration, appearance and behavior. Journal of the Fisheries Research Board of Canada 32, 1005-1017.
Sasaki, T., Nikaido, M., Hamilton, H., Goto, M., Kato, H., Kanda, N., Pastene, L. A., Cao, Y., Fordyce, R. E., Hasegawa, M. & Okada, N. 2005. Mitochondrial phylogenetics and
evolution of mysticete whales. Systematic Biology 54, 77-90.
STEEMAN, M. (2007). Cladistic analysis and a revised classification of fossil and recent mysticetes Zoological Journal of the Linnean Society, 150 (4), 875-894 DOI: 10.1111/j.1096-3642.2007.00313.x
Watson, L. 1981. Whales of the World. Hutchinson, London.
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Wow. If the intervertebral discs of Eubalaena ossified, the animal would be embolomerous! Convergence with anthracosaurs FTW!
This makes me wonder if the vertebrae of the Caperea skeleton are mounted too close together. But the ribs do overlap in the living (or anyway freshly dead) animal, as you showed us in the previous post.
The ankylosaurus of the whales perhaps ?
(some kind of protection against sharks or orca's)
Aha the Erebus and the Terror and their doomed voyage in the High Arctic.
Mysterie abounds
Just imagine
The commander of the terror, Francis Crozier might have seen the Thylacine in Tasmania before he went up north.
I saw one near Ushuaia a few years ago. It is pretty difficult to distinguish from a minke whale at sea, but it does swim in a peculiar way, leaving very large, widely spaced flukeprints on the surface. I wonder if its muscles are as different from those of other whales as its skeleton. May be it is in some unique way adapted to life in the stormy Southern Ocean, where it has to sleep and breath in 30-m swells.
Wow.. Vlad: is there anything you _haven't_ seen?
Felix Marx in his just published baleen whale phylogeny also recovers Caperea as closer to Balaenopteroids, which I think is the first morphological phylogeny to do so.
Rampant speculation: Caperea's overlapping transverse processes seem like they could inhibit spinal torsion (twisting), a major source of back injury. As for why it would need this - perhaps extensive flexation would be more prone to torsion?
I don't know much about whales so maybe I shouldn't hazard an opinion, but.. I think that David in post #1 may be correct about the vertebrae being mounted too closely together. Compare the first photo of Caperea's thoracic region with the next of Eubalaena. In the former there appears to be no spaces for the intervertebral discs while in the latter they're represented by the thick white bands. If the width of the discs are comparable in the two species, the transverse processes of Caperea wouldn't overlap nearly as much, if at all. In the close-up of Caperea's caudal spine there are gaps between the vertebrae where the discs would be, and no overlap between transverse processes. While the size & shape of the processes are indeed remarkable, it appears to me that much of the overlap is an artifact of inauthentic mounting. Am I missing something?
So, who else has overlapping ribs? And/or transverse processes of the vertebrae that look as if they might have reduced flexibility? Ichthyostega comes to mind for the ribs. And some of the Cynodonts (pre-mammal Synapsids) had weird vertebrae. This doesn't yet suggest a functional hypothesis to ME, but maybe someone else will see something.
So what do they want to be when they grow up?
--pirarucu?
--perpendicular tuna?
--bulldozing bottom feeders?
That whole set up looks like it's designed for high power fluke strokes. I just don't know enough about them to know whether it's for letting them bulldoze the sediments like an undersized gray whale, for slow cruising, with fast lunge feeding at the end (like the pirarucu), or whether they're going for the stiffened, streamlined body of the tuna.
Weird beastie.
Yeah, Darwinsdog brings up a really good point - that mount doesn't have any space for intervertebral discs. Then again, since I haven't actually read Buchholz (2010) I can't say what she says on the matter.
I am inclined to believe that the lack of disks is a flaw in this London specimen, given that the specimen mounted in Cambridge from the photo in last post appears to have considerably more space and less overlap. Still! The contrast between either specimen and the other whales is remarkable.
Thanks indeed for great comments. Darwinsdog (comment 7): you are right that including intervertebral discs would indeed insert more space between the vertebrae, and hence reduce the overlap between those enormous transverse processes... however, even with the intervertebral discs in articulation, the transverse processes still do overlap (Buchholtz 2010, p. 9 of preprint).
On the subject of overlapping ribs (comment 8): my starting point for this is always (for mammals)...
Jenkins, F. A. 1970. Anatomy and function of expanded ribs in certain edentates and primates. Journal of Mammalogy 51, 288-301.
Expanded ribs are present in anteaters, armadillos and lorisid primates: those of Cyclopes (pygmy anteater) and Arctocebus do actually overlap. Why? Jenkins (1970) suggested that - as hinted at by Cameron and others above - they increase stability of the vertebral column and/or thorax. This makes some sense in arboreal animals that anchor their hindquarters on a branch while reaching out with the forelimbs... but in a whale?
In thunniform or even carangiform swimmers it makes plenty of sense to restrict flexibility to the tail and keep the thorax stiff. This happened to the temnospondyls Archegosaurus and/or Sclerocephalus (I forgot) while they grew up.
But if so, why just Caperea??? It's not a swimmer with unusually high endurance compared to other whales, is it?
Flat ribs and processes would seem to maximize body structural rigidity while minimizing body girth (and perhaps reducing the caudal surface area).
I looked at the original images I took at higher magnification. There ARE spaces between the vertebrae. AS I recall from the dissection, these spaces are not very large. If you look at the vertebrae, you will see thin white bars which run transversely to support the flipper s and ribs. These bars are anchored by being sandwiched in between each vertebral body! You can see these white bars being sandwiched between vertebrae best in the first photo, towards the caudal end of the thorax. Also, I can't figure out ow to add photos to a response, but I just sent more photos to Darren of the head and tail and lateral aspects of this same specimen, along with a similar ventral view form a humpback whale skeleton at the New Bedford Whaling Museum (USA).
Darren: there's still a lot too see, although I'm almost done with marine mammals :-)
Note that Cyclops, armadillos (some) and lorisids are all animals that can roll into a ball.
Another one with weird vertebrae is, of course, the hero shrew :-)
What is the articulation between vertebra and rib like? It is difficult to see this in the pictures, but it doesn't look like much of a capitulum or tuberculum on the rib.
Joy,
Thanks for the clarification! Good to know the Buchholz paper corroborates the weird overlap. I've got a rather large pile of recent marine mammal literature that I have still waiting to be read.
By the way, after watching the fin whale episode of Inside Nature's Giants, I've decided that you are my new hero.
In the 4th photo, the fin/hand appears to have a cartilage 'claw' pointing upwardly, I guess for a broader fin stroke for fast turning, which would match the relatively large dorsal fin (parallel to dolphins)... I've read that sickly dolphins will propel with their forelimbs and keep their tail flukes inactive, perhaps a more primitive (semi-terrestrial swimming) mode of locomotion (sea lion style), this might account for Ross et als observation of body "flexibility".
If I understand properly, that 4th photo is of Eubalaena glacialis, not Caperea. The only place we see the fin of Caperea is in the live photo (#6), and it is relatively much thinner than the skeleton.
When puzzled, add ecology for more bafflement.
1) As Vlad posted in #3: "It is pretty difficult to distinguish from a minke whale at sea, but it does swim in a peculiar way, leaving very large, widely spaced flukeprints on the surface."
2) We know almost nothing about them, which strongly suggests they live and forage in places humans don't visit, e.g. the mid-ocean. I don't think it could live as a bulldozer without us noticing.
3) In a group of giants that focus ecologically on large batch capture of small prey, this is a small animal. It's also not a common animal (note we only have one posted live sighting and one live photo). This suggests that it hunts prey that occurs in highly scattered small clumps.
Put these together, and...? Probably they swim very efficiently, minimizing energy expenditure while in the search phase of foraging. Streamlining is about efficiency as well as speed, and Vlad's observation suggests it goes further per stroke than the equivalently sized minke whale. Given that the skeleton looks overbuilt for rigidity of the torso, it may accelerate rapidly in the capture phase of foraging, switching from "cruise" to "bruise" if you want a sound bite.
Does this fit the skeleton? Better than having it role in a ball as a defensive maneuver. It could be converging on a thunniform morphology.
Personally, I'd love to know what it is hunting.
That is the most stupid vertebral column I've ever seen. And I've seen a lot of stupid vertebrae in my time. Truly amazing. It looks like some vile giant prehistoric arthropod has crawled up inside the body cavity and attached itself to the central surface of the spine.
Apparently the vertebral column of the pygmy right whale is so strongly reinforced that it can survive being trodden on by an adult human!!!1!
Apparently the vertebral column of the pygmy right whale is so strongly reinforced that it can survive being trodden on by an adult human!!!1!
Would that be harmful to most whales? I'd think they'd be big enough that a human walking on them would be pretty insignificant. Do you mean the skeleton alone - without support of flesh, tendons ligaments etc - can be walked on?
Well, yes, but if it were a giant Carboniferous invertebrate such as Arthropleura, which incidentally looks quite a lot like the interesting vertebral design here and whose name means "rib joint", it would likely be able to survive said tread. (Now that's some in-depth pun!)
Just to go out on a limb here, did Walking With Monsters use the "trodden" phrase, MPT?
William:
I think Mike's comment was just a tongue-in-cheek reference to the bizarre hero shrew.
I wonder if this anatomy may provide some extra support for pectoral fins? Maybe Caperea uses it fins more for propulsion and for whatever reason the pectoral girdle lost its function?
Or might it be adapation for torsion? What benefit would a whale get from turning round? Create vortices in water for sucking up swarms of invertebrates? Push along seabottom to plough into sediment - would it show on baleen plates?
Are baleen plates of Caperea somehow unusual?
Ahhh, that would be a more sensible explanation, although it's surprising how well the Arthropleura bit worked out.
Wouldn't a selection pressure for acceleration predict a long, flexible torso?
Your other idea (unusually efficient swimming) looks very good to me.
This is incredibly interesting. I find the overlapping ribs to be a really cool aspect of the animal. But to address your title...yes, it is really wierd.
Hugely expanded lateral processes on vertebrae reminds me, of course, of Bungarus, which may be built extra tough to survive being trodden on. Can't really help with the whale thing though.
"By the way, after watching the fin whale episode of Inside Nature's Giants, I've decided that you are my new hero.
Posted by: Boesse | October 22, 2010 2:32 AM"
Thanks Boesse! I hope the ING series inspires lots of people to understand and love comparative anatomy and evolution. In your case, though, I think I'm "preaching to the choir" as the expression goes! :)
Yes, Dartian, I was indeed referring to the absurd claims about the Hero Shrew that certain credulous people who should know better seem to have bought into.
The hero shrew thing isn't true?
(I had heard of that, not sure why I didn't realize your comment was a joke on that...)
The hero shrew thing is anecdotal, for sure (though, notably, surprisingly well documented compared to most crazy anecdotes about animals). Mike refuses to accept it as possible... something to do with numbers, apparently.
Darren:
Has it ever been filmed?
Are hero shrews especially rare? It seems like it wouldn't be too difficult to test, if one could find a hero shrew.
Well the stepped upon Hero Shrew story is reported as a fact.
DR Congo is not the place of choice to study shrews, but if it occurs in Uganda, it should be possible to study it.
Yet another fascinating overlooked animal. Why some animals are overlooked? (Dhole, Candiru, Architethuis etc).
Yes, and I've seen it on TV. It's hard to believe, but it's real.
David,
Where did you see the footage? I must know!
William:
The IUCN, at least, doesn't think so and lists it as a 'Least Concern' species.
Jerzy:
According to the IUCN, it does (and also in Rwanda and Burundi).
Cameron:
I second that question.
(Incidentally, the hero shrew's German name is pretty awesome: Panzerspitzmaus.)
Hero shrew + Panzerspitzmaus = Wagner's shrew ?!
It could perhaps be noted here that the 'hero' part of the hero shrew's English name doesn't refer to the animal's behaviour. 'Hero shrew' is - allegedly - a direct translation of the shrew's name in the Mangbetu language; the phenomenal strength of its vertebral column led the local people to believe that wearing a dead shrew (or parts of one) as a talisman somewhere about your body would make you yourself impervious to physical injury, and thus turn you into a heroic huntsman and warrior.
A huge brawl about the abilities of the hero shrew flared up at SVPCA 2010; it was initiated by my casual acceptance of the 'fact' that Scutisorex can do what the literature says it can. I am pretty sure I remember a photo (or.. still from a bit of footage) where the famous act is indeed being performed. But I can't recall where I saw it. It was black and white. The only footage I could find online is this.
Hmmm...Wrong sum then. Even the armored shrew name is somewhat misleading...
Well, after reading Darren's comment (I posted before reading it), my addition still make a bit of sense afterall...
I remember a photo or a footage , If I recall correctly, there was a man wearing Maasai-like traditional clothings standing on a shrew, or is it just my imagination ?
I can't recall myself where I saw it...
If I knew, I'd have told you. :-( It was some kind of Attenborough-style documentary, but obviously not by Attenborough, or you'd all have seen it. It was maybe 15 years ago. And it was in color, so it's not what Darren has seen.
Panzer means "armor".
David:
You are among nature documentary connoisseurs here. Please list whatever other details* you remember from that documentary; perhaps someone is able to recognise it.
* E.g.: Which other animals were featured? Was the documentary British, American, French, German, Japanese...? Who performed the stunt: a local Congolese/Ugandan person, or a member of the film crew? Etc.
None whatsoever. I'm very, very, very bad at remembering where I got knowledge from. I've been known to spend hours looking for something in 3 wrong books. It was probably on Austrian TV, so I didn't pay attention to whether it was a BBC, NHK, Discovery Channel, National Geographic production or whatever.
Oh yeah, a local man stepped on the shrew.
Thanks for posting Joy's photos of the Pygmy Right whale specimen that we articulated as part of the Whales Tohorä exhibition. Joy has already noted that the intervertebral distances are small in this animal. The articulation was based on the thorough dissection of animal in 1997 by James G. Mead, John Heyning, Sentiel Rommel, Tadasu Yamada, Catherine Kemper and myself. But also from CT scans of juvenile animals. Since the articulation I helped Emily Bucholtz with her wonderful work when she was here and we have significantly advanced the way we perceive this animal. Also two wonderful dissections, one with Joy and more recent one Nov 2010, have really given us great insight in to the anatomy of this species. Papers will follow I am sure!
For your interest the Whales Tohorä exhibit is currently at the Ontario Science centre in Toronto. The next venue will be at the Field Museum in Chicago opening in May. I hope you get a chance to see it!
Best wishes, Anton
Oh and for the record, I suggest never walking on a Caperea skeleton...ha ha they are amongst the most fragile of all species I have worked with! Cheers, Anton
Family wedding in Toronto, and I got to go to the Ontario Science Center, where the Te Papa (Wellington NZ museum) whale exhibition is having a visiting show: STRONGLY RECOMMENDED if you are in Toronto or somewhere else the show will go. Usual bunch of interpretative stuff (videos, inc. interviews with a number of New Zealand whale experts, etc etc etc), lots of stuff about Maori culture as relating to whales, but also more actual material than most museums show nowadays.
Including:
-- Skulls of abut eight species of Ziphiid
-- Two complete sperm whale skeletons (large (ca. 18 meter) male, smallish adult (?) female)
-- Some Ziphiid, and...
-- Skeleton of Caperea, probably the one in the photos here. (Hung from ceiling, so not ideal for close examination, but...)
--
Anyway...
Yes. Very weird. Not just shapes of vertebrae and ribs, but proportions. There are 17 pairs of ribs, and 16 "post-dorsal" vertebrae (i.e. ribless vertebrae after the last one with ribs). Length of post-dorsal spinal column about 6 feet, length of dorsal (just the section of spinal column with ribs: ribs are "swept back," so actual rib cage is maybe a foor or two longer!) about 7 feet, length of skull about 4 feet. (Measured by pacing off on floor while looking up at skeleton, but I'm reasonably confident of the proportions.)
... This is VERY WEIRD for a whale! For comparison I went and looked at the Fin Whale (Balaenoptera physalus) skeleton in the O.T.C. permanent collection: only 14 pairs of ribs, about 14 "lumbar + sacral" vertebrae (the first haemal arch being between the 15th and 16th centra aft of the rib cage, i.i.r.c.), another 14 or so caudals after that (it was mounted in a place that made the end of the tail hard to see), and the "sacro-lumbar" and "caudal" sections of the vertebral column were each (by eyeball) about the same length as or slightly longer than the dorsal series.
Just to keep the phylogenetic pot stirring...
Recent article in PLOS One,
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0021…
on the morphology of the petrosal in Mysticetes: all (known) extant species analyzed, Mammalodon and Eomysticetus taken as outgroups for the cladistic analysis.
Going JUST by the earbone, Caperea is recovered as closer to the right whales than to the Balaenopterids: C. is recovered as sister-group to the Balaena/Eubalaena clade.
Same analysis recovers a monophyletic Balaenopteroidea: Eschrichtius (sp?) is sister of the Megaptera/Balaenoptera clade. Authors note and comment on the recent study that placed Caperea with the rorquals; I won't try to summarize.