Goblin Sharks (Mitsukurina owstoni) may be among the largest of cartilaginous fishes. While generallycredited with a maximum total length of 3.8 meters (12’6″), one specimen appears to have exceeded that by far.
In July 2000, an enormous shark was accidentally captured in the northern Gulf of Mexico after being entangled in a line attached to a crab trap (Parsons et al. 2002). Only the jaws of the shark were kept by the fishers (Parsons et al. 2002) and it is unknown why they weren’t examined by the authors. Considering the fishers took the time to dissect the shark (Parsons et al. 2002) I’m puzzled that no measurements were provided. The above photo, while clearly demonstrating Goblin Shark morphology and giving the impression of great size, unfortunately lacks any landmarks which can establish scale. Fortunately, a second photograph focusing on the head was taken and it proved surprisingly informative about the Gulf shark’s size.
The rope proved to be the key. With a known diameter of 2.06 cm (0.8″) Parsons et al. were able to measure a snout to eye distance of 62.9 cm (2’1″). Scaling up from the previously largest known specimen yielded a total length of 5.4 m (17’9″) for the Gulf shark (Parsons et al. 2002). The authors suspected the figure may have been an underestimate as snouts become proportionally shorter with increased total length and so used an exponential regression to calculate a total length of 6.17 m (20’3″). I strongly suspect the latter figure is closest to reality. I calculated the above photograph shows about 3.5 meters (11’6″) of shark despite most of the tail being out of frame. The aforementioned 3.84 m specimen appears to have a proportionally much longer snout, lending credence to the notion that 5.4 m is an underestimate. Of course it would be nice if those jaws showed up – or better yet, a similarly-sized specimen – but the case for gargantuan Goblin Sharks seems compelling.
Is the Gulf shark some one-off freak? I suspect not. The Gulf shark was the first specimen ever recorded from the Atlantic coast of North America (Parsons et al. 2002) and is still apparently the only known (Castro 2011). Adult Goblin sharks have only been “occasionally reported” presumably due to their deep water habitat (Castro 2011) and this list suggests they are very occasional indeed. With such a small sample size, a lack of Gulf shark-sized individuals could just be a statistical quirk. Perhaps there is bias towards the capture of smaller individuals as a ~6 m individual (perhaps approaching a tonne in weight) could be prohibitively large for most vessels to catch, let alone haul on board and preserve. Here’s to hoping that a monstrous specimen scares the hell out of an ROV crew someday!
Goblin Sharks may be giants, but they are far from alone in the lightless depths and far from being the largest. More soon.
References:
Castro, J. (2011) The Sharks of North America. Oxford University Press.
Parsons, G. R., et al. (2002) First record of the goblin shark Mitsukurina owstoni, Jordan (Family Mitsukurinidae) in the Gulf of Mexico. Southeastern Naturalist 1(2), 189-192.
Stupendemys is just, well, stupendous. Even after encountering a ceiling-suspended specimen at the American Museum of Natural History, the ground-level replica at the Harvard Museum of Natural History came as a shock. Of course, part of this shock was due to having no idea there was even a replica at the museum, wandering off to see ‘Plasterosaurus’, and then coming face to scutes with a hunk of shell about the size of a dining room table.
The AMNH and HMNH carapaces appear to be replicas of MCZ(P) 4376, which has a strait carapace length of 2.18 meters (~7’2″) (Wood 1976). Despite almost being large enough to inhabit, this shell appears to be on the small side for Stupendemys geographicus. Wood estimated another specimen to have an SCL of 2.30 m (7’7″), Bocquentin and Melo (2006) mentioned a 3.18 m (10’5) SCL specimen, and Scheyer & Sanchez-Villagra (2007) sampled two, one which was ~2-3 m (~6’7″ to 9’10″) in SCL and another which was 3.30 m (10’10″) with a carapace width of 2.18 meters. It’s almost beyond belief that the turtle body plan would still be functional into the multi-ton range – I’m especially curious how egg laying was accomplished – but I suppose stranger things have happened.
Stupendemys is remarkable for reasons other than being about the size of a compact car. At the anterior end of the carapace is a thickened and upturned ‘collar’, apparently unique among turtles (Wood 1976). Wood examined two S. geographicus specimens, and as one (pictured above) had a more developed collar, he speculated that it may be a secondary sexual characteristic. The other Stupendemys, S. souzai, has a collar which is developed to a similar degree but is vertical rather than curled back (Bocquentin & Melo 2006). Bocquentin & Melo speculated that S. souzai would not have been able to inhabit areas with swift currents and would have been restricted to swamps and small streams; the authors also curiously imply that S. geographicus was marine due to its association with the turtle Bairdemys. Whether or not S. geographicus is marine still appears to be an open issue (Sánchez-Villagra & Scheyer 2010); I feel obliged to point out that ostensibly ”freshwater” turtles wandering around in marine settings are not uncommon… but that’s a story for another day.
Underneath the collar is a deep median notch which, owing to comparisons with the distantly related Platysternon, Wood took as evidence that Stupendemys had a similarly large, non-retractile and heavily plated head. Platysternon doesn’t have exclusive ownership of similarly deep notches (also present in some snapping turtles, musk turtles, seaturtles, et cetera) and among the much closer relatives of Stupendemys (also members of Podocnemididae) Erymnochelysand Peltocephalus have big heads and prominent but comparatively shallow notches. I see no reason to think that Stupendemys had a radically different approach to neck retraction than other side-necked turtles as suggested by Wood, although of course further study of the neck vertebrae and (when found) the skull will be needed before making any conclusions.
Despite having no known skull (the above is enlarged Caninemys material), this didn’t stop authors from speculating on the diet of Stupendemys. Wood postulated it was largely or entirely herbivorous due to its size, as he was under the curious impression that the largest living turtles (terrestrial and marine) were herbivorous – was the famous jellyfish-heavy diet of Leatherbacks not known back then? Bocquentin & Melo curiously stated that Stupendemys had the appearance of a “predaceous bottom-dweller” but didn’t explain how they arrived at that conclusion. My own nearly-baseless speculation is that Stupendemys was a generalized omnivore – considering how much growth they had to accomplish, it seems unlikely for them to refuse anything. Then again, Leatherbacks attain huge sizes on jellyfish, so Stupendemys could very well have been up to something completely ridiculous.
References:
Bocquentin, J. & Melo, J. (2006) Stupendemys souzai sp. nov. (Pleurodira, Podocnemididae) from the Miocene-Pliocene of the Solimões Formation, Brazil. Revista Brasileira de Paleontologia 9(2), 187-192. Available.
Sánchez-Villagra, M. R. & Scheyer, T. M. (2010) Fossil Turtles from the Northern Neotropics: The Uromaco Sequence Fauna and Finds from Other Localities in Venezuela and Colombia IN: Sánchez-Villagra, M. R. et al. (eds.) Uromaco and Venezuelan Paleontology. Indiana University Press.
Scheyer, T. M. & Sánchez-Villagra, M. R. (2007) Carapace bone histology in the giant pleurodiran turtle Stupendemys geographicus: Phylogeny and function. Acta Palaeontologica Polonica 52(1), 137–154. Available.
Wood, R. C. (1976) Stupendemys geographicus, the world’s largest turtle. Breviora 436, 1-31. Available.
[E]ntia non sunt multiplicanda praeter necessitatem
- Ed L. Bousfield & Paul H. LeBlond, Pipefish or Pipe Dream?
Spatio-temporal quantum phenotype “type” manifestations of Dæmoneojersianus nomen-complex. Rightenover:Dæmoneojersianus brunetii sp. nov.; Down-Bottom:Cadborosaurus willsi (LeBlond & Bousfield 1995) Nomen Nudum; Leftmost: Hypsignathus monstrosus Species Inquirenda; Also Depicted:Halichoerus grypus Nomen Oblitum.
Through the sands of Time immemorial, Mankind have run afoul of Hippocephali even a child could distinguish from the familiar Equus. The close-minded Modern Linnaeusists brush ”Halichoerus grypus” under the rug under the label “seal” and clumsily force ”Hypsignathus monstrosus” into the pigeonhole “bats”. But how can species with the heads of horses be spread across entire distinct Orders of Mammalia? They cannot be. The Cult of Taxo-”nomists” haughtily look down upon LeBlond and Bousfield’s ”Cadborosaurus willsi” – that brave and noble classification which tragically fell upon deaf ears – and none but myself have the courage to describe Dæmoneojersianus brunetii (sp. nov. – this paper). It is clear these Phylo-infected “taxonomists” care more for making genetic “information” dance like a puppet on its strings at their whims upon gels than a True classification. Only I have the bravery and aptitude to classify Animalia, as I will heretofore demonstrate.
Analysis:
Holotype and Lectotype of Dæmoneojersianus brunetii. Diagnosis: Classic Hippocephalic condition; Limb pair I/II clearly distinguished; cranial appendages; neck flexibility characteristic of amphicoelous cervicals; trifurcate (fluke-like) caudal appendage.
Actual knowledge about a taxon is not contained within DNA. This knowledge derives from direct observation of morphology
- Malte C. Ebach, Marcelo R. de Carvalho, & Silvio S. Nihei, Saving our science from ourselves: the plight of biological classification.
Syntype of Dæmoneojersianus brunetii sp. nov. Diagnosis: Hippocephalic condition; cranial appendages; pseudo-ziphiid condition; Limb pair I/II fusion; manus reduced to digits II, III, & IV; flukes absent.
What these Skeptics and Debunkers trot out as “fossil” “evidence” is but a fool’s dream. How can bone turn to stone? No more so than a barnacle could transform into a bird! The objects known as fossils were carved by the Victorian Sentinelese to fool Sir Richard Owen into believing a “pre”-history; the Sentinelese now reign in the Earth’s Core, waiting for Humanity to grow weak and flabby from belief in “Evolution”, and then they will strike. For more on our would-be overlords and other wonders please consult Bühler’s Subterranea Victores et alia Mirabilia, of which I have the only copy extant.
[I]n animals that metamorphose, the basic types of larvae originated as adults of different lineages, i.e., larvae were transferred when, through hybridization, their genomes were acquired by distantly related animals.
- Donald I. Williamson, Caterpillars evolved from onychophorans by hybridogenesis
Syntypes of Dæmoneojersianus brunetii. Diagnosis: “Cadborosaurus” form ontology as follows: 5 humps, 5 loops, 4 loops, 1 hump, serpentine/crocodilian. Fluke structures and heads shared in both life-stages.
A procession of the damned. By the damned, I mean the excluded. We shall have a procession of data that Science has excluded.
- Charles Fort, The Book of The Damned
Paratype of Dæmoneojersianus “The Danish Sea-Monkey” type I/II transitional form. Diagnosis: Cranial appendage; Limb pair III fused into long “tail”; Hippocephaly mildly developed due to juvenile condition.
How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth?
Sherlock Holmes, The Sign of the Four
All I want is to know things. The black gulph of the infinite is before me
- H. Phillips Lovecraft, Letter to Frank Belknap Long (27 February 1931)
Discussion:
As incontrovertibly demonstrated in the Analysis above Dæmoneojersianus brunetii is composed of four distinct adult forms: 2 incorrectly described as a seal and a bat, another as a cryptid, and another unknown. For those of you for whom this analysis was somehow not clear enough, I present this diagrammatic summary:
What is the Ultimate Species, that which for the whole process of Creation set in motion by our Space-Progenitors was for?Is it man with his enlarged forebrain, well-developed buttocks, and ability to travel to the moon? No, for Man is weak and easily overpowered by the lowliest female orangutan. Is it the bacteria – the Chaos infusorium of Linneaus – with their infinite adaptability and fast generations?No, for even Man will surely ever hold them at bay with His chemical concoctions.No, the ultimate species is so Ultimate for the recognition it does not get, except from those smartest of humans.It allows itself to be seen under certain guises, yet adopts others so probable only a fool could believe them.When it is too often seen, it transforms into another beast with no seeming connection.They can never be caught, or if they are seemingly so, leave but a shell for plodding Man to find and ponder over. It is only the wisest of us that can see them, see the patterns. I am smarter than everyone, and no doubt myopic fools will assail my monolith of logic with their “Razor of Ockham” and their “Causality” – and it shall be their DOOM!
References:
Bousfield, E. L., & LeBlond, P. H. (2011) Pipefi sh or Pipe Dream? Journal of Scientifi c Exploration, Vol. 25, No. 4, p. 779–780, 2011 0892-3310/11
Ebach, M. C., et al. (2011) Saving our science from ourselves: the plight of biological classification Rev. Bras. entomol. vol.55 no.2 São Paulo June 2011 Epub June 17, 2011 Epub June 17, 2011 http://dx.doi.org/10.1590/S0085-56262011005000005
Williamson, D. I. (2009) Caterpillars evolved from onychophorans by hybridogenesis
Proc Natl Acad Sci U S A. 2009 November 24; 106(47): 19901–19905.
To once again shamelessly ride the coattails of research in the news, Nilsson et al. (2012) argued that the enormous eyes of Architeuthis and Mesonychoteuthis are adaptations for detecting Sperm Whales (Physeter). The authors demonstrated that pupils larger than 25 mm are subject to diminishing returns except in the ability to discern large moving objects at great depths from the disturbance to bioluminescent organisms. They calculated that below 600 meters, 90 mm pupils would be able to discern a Physeter 120 m away, allowing the cephalopods an opportunity for ”suitably timed and forceful escape behavior”. The data on eye effectiveness are fascinating and the proposed eye function seems plausible, however the paper contains some claims and speculations which are… troubling.
A (barely) living _Architeuthis_. From Wikipedia Commons.
Nilsson et al. claimed that Architeuthis and Mesonychoteuthis have disproportionately large eyes but presented no compelling reason why. They cited Zeidberg (2004) and stated “the allometric growth factor [of eye diameter relative to mantle length] for smaller squid is below 0.7″ but failed to mention the study only covered growth within the species Doryteuthis opalescens. The application of intraspecific allometry from a distant relative is pointless and I see no reason to dismiss the possibility that Giant and Colossal squid eyes are ‘normal’. Comparisons are complicated for Architeuthis due to its (apparent) phylogenetic isolation but compared to other oegopsids it seems positively modest. Mesonychoteuthis is not isolated and other cranchiids(when not stalk-eyed paralarvae) appear to have the largest eyes which can plausibly fit on a head, and beyond. This doesn’t necessarily mean Architeuthis and Mesonychoteuthis aren’t abnormal for their size, but far more interspecific data are needed on adult cephalopod eye size before making any pronouncements.
_Haliphron atlanticus_ from Wikipedia Commons.
Nilsson et al. imagined a scenario where Physeter predation drove gigantism in squids since large body size would offer more power to escape and would be needed to “build, sustain, and propel a pair of soccer-ball-sized eyes”. They do not appear to have realized that there is another cephalopod with eyes just as big as those of the Giant and Colossal Squids, Haliphron atlanticus. The Mesonychoteuthis measured by Nilsson et al. had an eye 270-280 mm in diameter and the Architeuthis eye diameter calculated from a photograph was “at least” 270 mm; in comparison, the largest Haliphron had eyes “about” 40% of the 0.69 m mantle length (O’Shea 2004) or ~276 mm. The Mesonychoteuthis was apparently the individual with a 2.5 m mantle and weight of 495 kg, compared to only 75 kg for the Haliphron (O’Shea 2004). The mass (and mantle length) of the Architeuthis measured by Nilsson et al. was not given, but is undoubtedly far more than Haliphron as the head width appears to be around 60 cm. Unless there is some fundamental difference between squid and octopus eyes, this suggests that Architeuthis and Mesonychoteuthis could potentially have much larger eyes. Why Haliphron would have some of the proportionally largest eyes for a cephalopod despite already being the largest octopus is puzzling. Like the squids it is prey of Physeter(Santos et al. 2002) but so is the other giant octopus Enteroctopus dofleini (Fiscus et al. 1989) with its modestly-sized eyes, among myriad other deep-sea cephalopods.
This is a rich topic and there are so many other aspects to explore. As hinted at the similar size of Architeuthis, Mesonychoteuthis, and Haliphron eyes – have these species reached some structural or functional limit? How do the eyes of other giant cephalopods (e.g. Galiteuthis phyllura, Megalocranchia fisheri, Onykia robusta, Taningia danae, Dosidicus gigas) compare? One study found the main stomach contents by mass of Southern Sleeper Sharks (Somniosus antarcticus) to Mesonychoteuthis (52%) with Architeuthis present in considerable quantities as well (15%) (Cherel & Duhamel 2004) – how often do the sharks prey on the cephalopods and are they more efficient predators than Physeter due to their much smaller size? Is it possible the eyes have some other, unforeseen function? Alas, Nilsson et al. discuss ichthyosaurs.
_Ophthalmosaurus icenius_ from Wikipedia Commons.
Ichthyosaurs are characterized by greatly enlarged eyes (Sander et al. 2011) with smaller species having an eye diameter/body length relationship comparable to owls and penguins (Motani et al. 1999 – fig 2.). Ophthalmosaurus (above) has the proportionally largest eyes of any ichthyosaur (>220 mm for a 4 m body), frequently shows evidence of the bends, and was calculated to be capable of diving to at least 600 m (Motani et al. 1999) and thus the case seems good that its eyes were functioning similar to those of giant cephalopods. As for what they were detecting, Nilsson et al. suggest giant pliosaurs… I can’t find any other suggestions of pliosaurs cruising the lower end of the mesopelagic zone. Well, at least they didn’t bring up that one Stupid Fucking Hypothesis which I refuse to directly acknowledge. Temnodontosaurus had sclerotic rings 253 mm in diameter relative to a 9 m body length and a similar frequency of the bends as Ophthalmosaurus (Motani et al. 1999) and Nilsson et al. further argue that the laterally-facing orbits and lack of adaptation for improving forward-vision means their objects of interest could appear in any direction, and the authors suggested conspecifics at great depths as the objects of interest. I see no reason to think the large eyes of Temnodontosaurus are due to anything but scaling and it certainly seems that large cetaceans (with the largest extant vertebrate eyes) also have severely reduced or absent forward vision. Nilsson et al. talk about ichthyosaurs in general terms and unfortunately imply that they were all adapted for detecting large objects, which is a shame since eyes rivaling those of giant cephalopods seem to have been restricted to the larger species (and Ophthalmosaurus).
It is worth stating again that I think Nilsson et al. (2012) is fascinating research but it applies its findings to simple scenarios without great justification. I don’t think the research is necessarily wrong – Physeter-detection seems highly compelling – but there is undoubtedly far more to possessing freakishly big eyes than the authors discuss.
References:
Cherel, Y. & Duhamel, G. (2004). Antarctic jaws: cephalopod prey of sharks in Kerguelen waters. Deep-Sea Research I 51, 17–31. Available.
Fiscus, C. H., et al. (1989) Cephalopods from the Stomachs of Sperm Whales taken off California. NOAA Technical Report NMFS 83, 1-10. Available.
Motani, R., et al. (1999) Large eyeballs in diving ichthyosaurs. Nature 402, 747. Available.
Nilsson, D-E., et al. (2012) A Unique Advantage for Giant Eyes in Giant Squid. Current Biology 22, 1-6. DOI 10.1016/j.cub.2012.02.031
O’Shea, S. (2004) The giant octopus Haliphron atlanticus (Mollusca: Octopoda) in New Zealand waters. New Zealand Journal of Zoology 31, 7–13. Available.
Sander, P. M., et al. (2011) Short-Snouted Toothless Ichthyosaur from China Suggests Late Triassic Diversification of Suction Feeding Ichthyosaurs PLoS ONE 6(5): e19480. doi:10.1371/journal.pone.0019480
Santos, M. B., et al. (2002) Additional notes on stomach contents of sperm whales Physeter macrocephalus stranded in the north-east Atlantic. Journal of the Marine Biological Association of the UK 82, 501-507. Available.
Zeidberg, L. D. (2004) Allometry measurements from in situ video recordings can determine the size and swimming speeds of juvenile and adult squid Loligo opalescens (Cephalopoda: Myopsida). The Journal of Experimental Biology 207, 4195-4203. Available.
I’m late to the story, but the first-ever video of the beaked whale Tasmacetus shepherdi is beyond irresistible.
The 2006 paper referenced in the video is undoubtedly Pitman et al. (2006), which provided the first accurate description of the whale’s coloration. It is mind-boggling that the external appearance of a whale could be uncertain until so recently. Indopacetus, the external appearance of which wasn’t nailed down until 2003, looks very similar to Tasmacetus but clearly isn’t the species in the video. The pale melon, long dark beak and white shoulder patch considered diagnostic for vessel encounters with Tasmacetus (Pitman et al. 2006) are clearly visible and I think I even caught a glimpse of the very distinctive cape. The 4 (or 5?) whales in the video are consistent with other observations of group size for the species (3-6), although the previous sample size was only four (Pitman et al. 2006). One interesting detail from the video is that it answers Pitman et al. (2006)’s query as to whether or not the blow of this species would be visible from a vessel, as it shows that the blows are perhaps as prominent as those from Berardius and Hyperoodon. There are undoubtedly other things that the video shows that I haven’t picked up on, so I’ll try and get the jump on the paper when it eventually surfaces.
_Tasmacetus_ is a bit toothier than your bog standard beaked whale. From Mead and Payne (1975).
The coloration of Tasmacetus is curiously dolphin-like as it exhibits a dark cape, flipper stripe and no differences between sexes and age groups (Pitman et al. 2006). Another curiously dolphin-like trait is that in addition to the battle teeth, both jaws have full sets of functional teeth (Pitman et al. 2006). This is not necessarily a radical departure from other beaked whales. The fossil ziphiids Messapicetus and Ziphirostrum apparently had functional teeth in both jaws (Lambert 2005) despite being relatives of the conventionally toothed Ziphius(Bianucci et al. 2007). Mesoplodon grayi has apparently functional teeth in its upper jaw and non-battle teeth are sometimes present in the lower jaw as well (Robson 1975). It’s certainly puzzling what retentions and/or reversals could have led to such an odd arrangement of toothy species, although since beaked whale systematics show no sign of getting resolved any time soon perhaps it’s best not to think about this at the moment. Ziphiids certainly don’t seem to be close relatives of dolphins so it seems likely the dolphin-y traits of Tasmacetus are convergences rather than retentions. As for why they’re pretending to be giant dolphins, who knows.
I also can't resist bizarre reconstructions. This one is fine up until the flippers and then... yikes. From Mead and Payne (1975).
References:
Bianucci, Giovanni et al. (2007) A high diversity in fossil beaked whales (Mammalia, Odontoceti, Ziphiidae) recovered by trawling from the sea floor off South Africa. Geodiversitas 29(4), 561-618. Available.
Lambert, O.. 2005. Systematics and phylogeny of the fossil beaked whales Ziphirostrum du Bus, 1868 and Choneziphius Duvernoy, 1851 (Mammalia, Cetacea, Odontoceti), from the Neogene of Antwerp (North of Belgium). Geodiversitas 27(3), 443-497. Available.
Mead, J. G. (2008) Shepherd’s Beaked Whale (Tasmacetus shepherdi). IN: Perrin, W. F., Würsig, B., & Thewissen, J. G. M. Encyclopedia of Marine Mammals. Academic Press.
Mead, J. G. & Payne R. S. (1975) A specimen of the Tasman Beaked Whale, Tasmacetus shepherdi, from Argentina. Journal of Mammalogy 56(1), 213-218.
Pitman, R. L. et al. (2006) Shepherd’s Beaked Whale (Tasmacetus shepherdi): Information on appearance and biology based on strandings and at-sea observations. Marine Mammal Science 22(3), 744-755. Available.
Robson, F. D. (1975) On vestigial and normal teeth in the Scamper-Down Beaked Whale, Mesoplodon grayi. Tuatara 21(3), 105-107. Available.
The archipelago Haida Gwaii lies 80 km off British Columbia and is home to a number of endemics including a subspecies of American Black Bear, Euarctos americanus carlottae (Byun et al. 1997). It seems surprising that a viable population of bears could survive on such isolated and small islands (~10,000 km2 total) which is made further remarkable by Haida Gwaii American Black Bears being the largest subspecies (Byun et al. 1997 – citing Foster 1965). Haida Gwaii bears also have distinctive morphology compared with other bears including a more elongate skull, narrower rostrum, less arched cranium and larger teeth with particularly elongate last upper molars (Osgood 1901).
Haida Gwaii Black Bear (left) and a more typical Black Bear, presumably mainland. From Osgood (1901).
Despite their distinctive morphology, an early mtDNA analysis failed to distinguish Haida Gwaii bears from their coastal relatives (Byun et al. 1997). This, coupled with the coastal/island bears clearly grouping away from continental subspecies, was interpreted as indicating that the coastal/island bears had a recent common ancestor from a glacial refuge, probably in the (now submerged) Hecate Strait (Byun et al. 1997). Agnarsson et al. (2010) found similar results with coastal/island bears forming a distinct clade and with its sub-clades having low bootstrap values (i.e. being infrequently recovered). I’m curious why the Haida Gwaii bears themselves formed a clade only half the time – gene exchange with the mainland certainly cannot be common – but perhaps it could indicate just how recently evolved the bears are. Humans have inhabited Haida Gwaii for 8000 years (Reimchen 1998) and it is strange to think that a distinctive subspecies could evolve while sharing an island with our species.
As for how the Haida Gwaii bears got their size, Byun et al. (1997) hypothesized that they represent the ancestral size while other American Black Bears shrunk. Wolverton & Lyman (1998) commented that large bears from the American Midwest assumed to be Pleistocene in age because of their size were actually only a couple hundred of years old, which makes me wonder if similar assumptions led to Byun et al.’s hypothesis. Whether large size was retained or gained, island-dwelling Black and Brown Bears (Ursus arctos) are generally larger than their mainland counterparts (Meiri et al. 2006). One striking example is the Kodiak Bear (U. a. middendorffi) which parallels the Haida Gwaii bears in being the largest subspecies and living on a surprisingly small archipelago (~14,000 km2) in the Pacific Northwest. What factors could there be on islands which allows them to support bears of such size? For Brown Bears, coastal salmon-eating bears were the largest (Hilderbrand et al. 1999) and Haida Gwaii bears consume considerable amounts of Chum Salmon (Oncorhynchus keta) (Reimchen 2000). Of course I haven’t seen a correlation between salmon availability and Black Bear size tested yet and there could very well be a host of other minor factors which allowed Haida Gwaii bears to reach their superlative size. Say, isn’t there supposed to be an ‘Island Rule’ where large mammals get smaller and vice versa? It seems not to apply to carnivorans (Meiri et al. 2006) – so why is it still referred to as a “rule?”?
References:
Agnarsson, I. et al. (2010). Dogs, cats, and kin: A molecular species-level phylogeny of Carnivora. Molecular Phylogenetics and Evolution 54, 726–745. Available.
Byun, S. A. et al. (1997) North American Black Bear mtDNA Phylogeography: Implications for Morphology and the Haida Gwaii Glacial Refugium Controversy. Evolution 51(5), 1647-1653. Available.
Foster, J. B. (1965) The evolution of the mammals of the Queen Charlotte Islands. BC Prov. Mus. 14, 1-30.
Hilderbrand, G. V. et al. (1999) The importance of meat, particularly salmon, to body size, population productivity, and conservation of North American brown bears. Canadian Journal of Zoology 77, 132–138. Available.
Meiri, S. et al. (2006). The generality of the island rule reexamined. Journal of Biogeography 33, 1571–1577. Available.
Osgood, W. H. (1901) Natural history of the Queen Charlotte Islands. North American Fauna 21, 7-50. Available.
Reimchen, T. E. (2000) Some ecological and evolutionary aspects of bear–salmon interactions in coastal British Columbia. Canadian Journal of Zoology 78, 448–457. Available.
Reimchen, T. E. (1998) Nocturnal Foraging Behavior of Black Bears, Ursus americanus, on Moresby Island, British Columbia. Canadian Field-Naturalist 112(2), 446-450. Available.
Wolverton, S. & Lyman, R. L. (1998) Measuring Late Quaternary Ursid Diminution in the Midwest. Quaternary Research 49, 322-329. Available.
_Latimeria chalumnae_ from the Harvard Museum of Natural History. The famous _Kronosaurus_ lurks in the reflection.
What is going on with coelacanths? The first dorsal fin is a typically fishy rayed structure yet the second is fleshy and lobed. Considering that tetrapod limbs are derived lobed fins and the anal fin is also lobate this makes coelacanths hexapedes of a sort. It is baffling how the nickname “Old Fourlegs” got attached to a creature with such bizarrely arrayed and numerous appendages.
A phylogeny of lobed fins from Friedman et al. (2007).
Coelacanths can’t really be said to have “legs” or even proper limbs. Tetrapod limbs are defined as having mobile wrists, ankles and digits (Shubin et al. 2006) whereas coelacanth lobed fins are made out of a series of metapterygia with radials on the anterior and posterior margins (see above). The Devonian coelacanth Shoshonia had pectoral fins with some traits more typical of early tetrapodomorphs than extant coelacanths, most notably by having pronounced asymmetry (Friedman et al. 2007). This indicates that coelacanth lobe fins became less limb-like during their evolution and Friedman et al. (2007) argue that the extant fishes most likely to give insight into early tetrapod limbs are basal actinopterygians such as bichir and sturgeon. Thus extant coelacanths should not be viewed as evolutionarily stagnant and the nickname “Old Fourlegs” somehow manages to be even more wrong.
From Wikipedia Commons.
The medial second dorsal and anal fins of Latimeria are “practically identical” and mirror one another (Forey 1998). These lobed medial fins exhibit skeletal, muscular and innervational similarities with the paired lobed fins (Ahlberg 1992 – citing Millot and Anthony 1958) and all the lobed fins appear capable of considerable rotation (Forey 1998). Judging by videos it appears that the medial lobed fins beat in sync whereas the pectoral and pelvic pair does not. The medial lobed fins particularly resemble the pelvic fins and the basal plate supporting the former appears very similar to the pelvis of the latter rotated 90 degrees (Ahlberg 1992). Ahlberg (1992) suggested that the lobed median fins came into being through a switch in gene expression although noted more fossils and evidence from development and genetics would be needed. Unfortunately so far as I can tell this topic has yet to be explored further.
From Wikipedia Commons
The caudal fin of coelacanths is normally interpreted as a three-part structure (Forey 1998) however in the description of the Jurassic coelacanth Parnaibaia maranhaoensis Yabumoto (2008) interprets it as being composed of a third dorsal, second anal fin and a proper caudal. Third dorsals and second anals are not without precedent (e.g. cod) however the degree of disparity between fins that coelacanths display certainly is. Perhaps the medial lobed fins of coelacanths aren’t true dorsal or anal fins at all but totally novel replications of the pelvic fins. Alternately it could be possible that coelacanths had ancestors with a superfluous number of medial fins or that the caudal fin split into three parts for some reason; either way it seems likely that something very very strange is happening to coelacanths genetically and developmentally.
References:
Ahlberg, P. E. (1992). Coelacanth Fins and Evolution. Nature 358, 459. Available.
Forey, P. L. (1998). History of the Coelacanth Fishes. Natural History Museum: London.
Friedman, M. (2007). First discovery of a primitive coelacanth fin fills a major gap in the evolution of lobed fins and limbs. Evolution & Development 9(4), 329-337. Available.
Millot, J. & Anthony, J. (1958-1965) Anatomy de Latimeria chalumnae. Vol. I-II. Paris.
Shubin, N. H. et al. (2006). The pectoral fin of Tiktaalik roseae and the origin of the tetrapod limb. Nature 440 (6), 764-771. Available.
Yabumoto, Y. (2008). A new Mesozoic coelacanth from Brazil (Sarcopterygii, Actinistia). Paleontological Research 12(4), 329-343. Available.
Lophenteropneust - the worm that never was. From Pawson (2003).
My younger and more credulous self continuously pored over the Regional Checklist of Mystery Animals and one of the many cryptic entities which captured my imagination were lophenteropneusts, deep-sea chimerical invertebrates known only from photographs. This was during the informational Dark Age of the early 00′s and having that one scrap of information to go on made them all the more tantalizing. Revisiting the topic on a whim led to the shocking discovery that one ‘lophenteropneust’ was captured before the checklist was even composed and that the hypothetical worm was a gross distortion of an already fantastic group.
Unidentified acorn worm. From Wikipedia Commons.
‘Lophenteropneusts’ were initially interpreted as a transitional form between pterobranchs (sea angels) and enteropneusts (acorn worms) and used to argue that the latter had evolved into the former (Holland et al. 2005). Both the angels and the worms are hemichordates, deuterostomes with a three part (proboscis/collar/trunk) body plan and separate coelom in each region (Swalla and Smith 2008 – citing various). Hemichordata has been consistently recovered as the sister clade of echinoderms (e.g. Swalla and Smith 2008) and knowing what the ancestral hemichordate looked like could be very informative about the evolution of echinoderms and even more distant relatives such as vertebrates. The two hemichordate body plans are strikingly disparate as acorn worms are solitary, have numerous gill slits and a strait gut whereas sea angels are colonial tube dwellers, have reduced or absent gill slits, a u-shaped gut and feed with tentacles (Cannon et al. 2009). The ‘lophenteropneust’ looks like an acorn worm with sea angel tentacles glued on and was thus interpreted as a transitional form. Lacking the original source I’m puzzled why the hypothetical worm was interpreted as evidence of an acorn worm to sea angel transition and not vice versa. Despite the dubiousness of ‘lophenteropneusts’ the hypothetical relationship between the hemichordates has some merit.
The sea angel _Rhabdopleura normani_. From Wikipedia Commons.
Cameron et al. (2000) recovered pterobranchs as being within Enteropneusta in a molecular analysis and noted that pterobranchs share a number of traits with harrimaniid sea acorns such as small size, post-anal tail in harrimaniid juveniles, reduction in gill slits, filter feeding in some harrimaniids, and others. Cannon et al. (2009) reached a similar arrangement in their molecular phylogeny yet Osborn et al. (2011) did not. This hypothesis is still very much an open question – invertebrate biology seems to be full of these – and hopefully some sort of consensus will eventually be reached.
'Lophenteropneust'. From Thiel (1979).
After a few botched attempted at collection (Barnes 2004) in 2002 an acorn worm with a broader collar than any other described species was videotaped, collected and formally named Torquarator bullocki (Holland et al. 2005). Wide-collared acorn worms had been observed and photographed previously (but not captured) and in their review Holland et al. (2005) discovered that ‘lophenteropneusts’ showed a similarly wide collar area with no readily apparent tentacles. The Thiel photograph (above) is the highest quality ‘lophenteropneust’ picture (Holland et al. 2005) and it seems to have similar collar morphology to Tergivelum baldwinae (see Holland et al. 2009) with no indication of the looped and feathered tentacles imagined to be present. Holland et al. (2005) conclude that the ‘lophenteropneust’ concept was entirely based on misinterpreted low-quality photographs but that doesn’t mean that the worms behind them are at all boring.
Not concept art from Avatar 2 but an undescribed extra-wide-lipped acorn worm. From Holland et al. (2005).
Holland et al. (2005) found Torquarator bullocki unique enough to warrant its own family, Torquaratoridae, and while one analysis found a wide-collared species to fall within Ptychoderidae (Cannon et al. 2009) the clade was recently confirmed to be separate and monophyletic (Osborn et al. 2011). One issue is that extraction of genetic material from the type species and genus Torquarator bullocki has thus far failed however the family was also rediagnosed on morphology which the species displays (Osborn et al. 2011). Torquaratorids have a reduced to absent proboscis skeleton and an adult stomochord either absent or separated from the buccal cavity of the collar (Osborn et al. 2011). More remarkable traits displayed in Torquaratoridae include a deep sea habitat (acorn worms were previously regarded as primarily shallow water), no burrowing capabilities (the normal mode of life for acorn worms), controlled drifting (using gut contents as ballast, secreting mucous to increase drag in the water column) to travel between locations, the largest invertebrate eggs (outside of cephalopods) which may have something to do with the enigmatic planctosphaera larvae, far more morphological disparity than most acorn worms, and they are very specious with 13 species being added in one study compared to the prior total of 89 for all acorn worms (Osborn et al. 2011).
Going back to the impetus of this article, what does the discovery of torquaratorids mean for cryptozoology? The misinterpretation of ‘lophenteropneust’ pictures was used as a cautionary tale by Dubois and Nemésio (2007); the authors further discussed cryptozoological “problems” resulting from photographs being used to name species such as my old nemesis Cadborosaurus willsi. The sightings and photographs of ‘lophenteropneusts’ and other wide-collared acorn worms prior to 2002 (see Holland et al. 2005 for review) highlights an awkward period between initial observation and discovery which is surprisingly common. But is it cryptozoological? Since the earlier observations (and anecdote) of pre-discovery torquaratorids apparently did not lead to the discovery of Torquarator bullocki I would argue that no, it isn’t. This does not mean that photographs and even anecdotes are useless as tools for discovering new species (they’re not) but they must be treated with caution and restraint. I have a suspicion I’ll be discussing this extensively and excessively in the future.
References:
Barnes, R. S. K. 2004. Kingdom Animalia. IN: The Diversity of Living Organisms. Blackwell Publishing.
Cannon, J. T. et al. 2009. Molecular phylogeny of hemichordata, with updated status of deep-sea enteropneusts. Molecular Phylogenetics and Evolution 52, 17–24. Available.
Dubois, A. & Nemésio, A. 2007. Does nomenclatural availability of nomina of new species or subspecies require the deposition of vouchers in collections? Zootaxa 1409, 1–22. Available.
Holland, N. D. et al. 2009. A new deep-sea species of epibenthic acorn worm (Hemichordata, Enteropneusta). Zoosystema 31(2), 333-346. Available.
Holland, N. D. et al. 2005. ‘Lophenteropneust’ hypothesis refuted by collection and photos of new deep-sea hemichordate. Nature 434, 374-376. Available.
Osborn, K. J. et al. 2011. Diversification of acorn worms (Hemichordata, Enteropneusta) revealed in the deep sea. Proc. R. Soc. Bdoi: 10.1098/rspb.2011.1916
Pawson, D. 2003. Deep-sea dreams: diary of a mad lophenteropneust watcher. Deep-Sea Newsl. 32, 6–7. Available.
Swalla, B. J. & Smith, A. B. 2008. Deciphering deuterostome phylogeny: molecular, morphological and palaeontological perspectives. Phil. Trans. R. Soc. B 363, 1557–1568. Available.
Thiel, H. 1979. Structural Aspects of the Deep-Sea Benthos. Ambio Special Report 6, 25-31. Available.
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