Picture of the Day – Survivor

Earlier today, I noticed a small turtle upside-down on the edge of a highway median adjacent to Osamequin Bird Sanctuary. From its small size, the severity of the injury, and the fact it was totally unresponsive, I assumed it was roadkill. It’s always sad to see an animal as slow growing as a turtle dead, and what made this case particularly tragic is that it’s a Spotted Turtle (Clemmys guttata), now considered an endangered species (van Dijk 2011). I had placed the turtle in a box and noticed that every time I walked by, it seemed to be at a slightly different angle. I wasn’t imagining things, it was overcoming shock and beginning to move again. It initially only moved its back legs – making me fear it was paralyzed – but it soon began to use its front legs as well. By then a severe thunderstorm had broken out and not knowing when I’d be able to drop it off and not having access to veterinary manuals or the Internet, I used liquid bandages on the fracture (visible as the dark streak u) to hopefully stop the bleeding, prevent infection, and hold things in one piece as the turtle was becoming more active. The turtle did eventually make its way to a wildlife rehabilitator a few hours later and I hope all goes well.

What surprised me about this specimen is that, having extensively handled a female of the species, is that it was evidently male (thick tail, concave plastron – I couldn’t see the eyes though). Furthermore, is must have been coming from brackish water (as the median was too steep and high to climb) and wasn’t too far from where I found the baby snapping turtle and was in the same body of water in which I recently observed a terrapin. If the specimen recovers, this has me puzzled as to where it should be released, and considering that the species is doing so poorly, perhaps it would be best used in a breeding program.

References:

van Dijk, P.P. 2011. Clemmys guttata. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.1. <www.iucnredlist.org>. Downloaded on 26 June 2012.

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The Shadow over Portsmouth

In July 2002, Rhode Island had its only second* known fling with marine cryptozoology at Teddy’s Beach in Portsmouth. I was aware of this encounter since 2003 from Bruce Champagne’s “Type 3 Animal Test” but the existence of a newscast came as a total surprise. As with everything ever filmed, it’s on YouTube:

* Edit: I forgot about the “Block Ness Monster”. Thanks, Scott Mardis!

It’s… something. In Narragansett Bay, it makes the news when dolphins travel into the upper reaches, so the possibility of an unknown large, aggressive species cruising around is basically zero. It is tempting to dismiss the encounter at Teddy’s Beach as an inept description of some unknowable mundane species, but what if it’s a surprisingly accurate documentation of a very rare – but known – visitor to the Bay?

Before getting into what the Teddy’s Beach encounter may have been with, I’ll lay out all the available information as objectively as plausible.

Newscast: Sighting occurred on a late Tuesday afternoon, apparently under sunny conditions. Object “roughly” 15 feet long [4.57 meters]. Man “cleaning” wound in the water for an hour and a half nearby [and again two days later?!].

Female eyewitness: Object made hissing sound. Big teeth. Basketball-shaped face, went “in” [eyewitness made tapering gesture], was squared off [made gesture indicating bottom of face], had white coloration [made gesture apparently indicating throat]. Swam around and made physical contact with eyewitness. Contact indicated scales, also suggested to be on the face.

Male eyewitness: Object went “around” eyewitness [spread out arms, unclear meaning] got very close [perhaps 1-2 meters]. Had scales [“a couple” on head?]. Head shaped like a footbasketball [eyewitness made basketball-sized gesture]. Fangs compared to eyewitness’s fingers, gesture indicated 4-5 on bottom plus “two or three” on top plus “layers inside”. Blackish on top [of head]. White under neck. Shot water out of nose. Hissed [while spitting water?] at eyewitness. Object initially thought to be eel. Moved by “rolling” at first [white visible] then moved “like a barracuda” but also with a “hump” when “chasing” female eyewitness [gesture made seemingly indicating vertical and lateral oscillation].

Bruce Champagne: 5 meters in length [contra: 4.57 m]. Greenish-black on top [contra: blackish] white below. Basketball-sized eel-like head [contra: basketball-shaped and sized]. 10 cm long teeth [finger length?]. Investigated swimmer [contra: “chasing”]. Swam with “rolling” motion [contra: “rolling” and “hump”/”barracuda”-like]. Makes mention of body diameter being estimated [inferred from gesture made by male eyewitness?].

Champagne’s “Type 3” construct, purportedly 87% similar to the creature observed at Teddy’s Beach.

My colleague Markus Bühler suggested that perhaps the eyewitnesses encountered a Leatherback Seaturtle (Dermochelys coriacea). Leatherbacks have been documented from Hope Island (Raposa), nearly as far up the Bay as Teddy’s Beach. It came as a major surprise to me that leatherbacks enter Narragansett Bay at all, and I suspect that most other residents are not aware of their occasional presence. What’s especially intriguing about the leatherback hypothesis is that the “layers” of fangs described by the male eyewitness could be explained by keratinized spines:

Taken from WoRMS

The “two or three” fangs on the upper jaw could be explained by the projections of the leatherback’s upper beak; there aren’t four or five complimentary projections on the leatherback’s lower beak but perhaps the male eyewitness was counting some of the outlying keratinous projections. Leatherbacks have big round heads, so the comparisons to a basketball plausibly fit. It isn’t clear what going “in” and being squared off could mean on a basketball-shaped head, but perhaps they’re a reference to the wide mouth and the shape of a leatherback’s lower beak. Male leatherbacks have white throats (Ernst and Lovich 2009) which fits the eyewitness descriptions.

Taken from Dan Irizarry’s Flickr

The reported antagonistic behavior towards the female eyewitness is… curious. The mention of water coming out of the nose suggests respiratory issues, which means the “hissing” may have been labored breathing. Dermochelys has been reported to vocalize when in duress (Ernst and Lovich 2009) but I’m not clear if hissing is in their repertoire. Chasing a human without prompting would be strange for any animal, so perhaps it was swimming towards the eyewitnesses and the behavior was misinterpreted as aggressive. Leatherbacks will, however, act aggressively towards humans who provoke them:

Leatherbacks may attack boats without provocation. This video is also useful in showing that breathing at the surface can create the illusion of water coming out of the nose:

The initial impression of an eel-like creature would seem remarkable for an observation of a turtle, although the initial part should be stressed along with the male eyewitness’s gesture which may have indicated the object was wide. A length of around 4.57 meters is larger than any leatherback, but there is little reason to take reported sizes literally from any eyewitness. The presence of “scales” is problematic for leatherbacks, which lack them as adults, but it could have been possible that they were misinterpreted bony ossicles and/or mottled coloration. I am admittedly confused what sort of movement the male eyewitness was attempting to describe.

The leatherback hypothesis isn’t a perfect fit, but it’s far more likely an explanation than some bizarre unknown species. The fact that one of the largest living reptiles graces Rhode Island with its presence is fantastic enough as it is.

References:

Ernst, C. H. and Lovich, J. E. (2009) Turtles of the United States and Canada. John Hopkins University Press.

Raposa, K. Aquatic Birds, Marine Mammals, and Sea Turtles IN: An Ecological Profile of the Narragansett Bay National Estuarine Research Reserve. Available.

Picture of the “Day” – Returning Terrapin

A shoddy Internet connection and trip to Maine have thwarted my attempts to get content out there more frequently, let alone my lofty goal of once per day. I will have to look into this ‘stockpiling’ I’ve read so much about…

Anyways, today I managed to observe a Northern Diamondback Terrapin (Malaclemys terrapin terrapin) at Nockum Hill in Barrington, Rhode Island. Nockum Hill is the only known nesting site in the state (they’re endangered) and this is the first time I’ve seen one there. I have previously seen a roadkilled individual on a highway across the Barrington River from the nesting site and another wandering around a few miles south, so it was a relief to see that the species was still out there and nesting in protected areas.

Picture of the Day – Centenarian Box Turtles?

A New York Zoological Society photograph, from Oliver (1955).

Box Turtles (Terrapene) do not seem like the most likely creatures to live for over 100 years. Compared to Aldabra and Galápagos giant tortoises they’re minuscule (note the human hand in the above photo) and adults have predators, although few are effective (Ernst and Lovich 2009). The hardest data on Box Turtle longevity appear to be from Henry (2003) who documented that individuals of the Eastern subspecies (T. carolina carolina) marked in a 1945 study were still alive. Miller (2001) found that Three-Toed Box Turtles (T. c. triunguis) estimated to be over 60 years of age were gravid and had clutch sizes similar to those of younger individuals. If Box Turtles really do age at a negligible rate as their continued reproduction suggests, this makes the remarkable age claims more plausible. Oliver (1955) noted that while some impossible dates have been carved into Box Turtle shells (e.g. 1492) he argued that some unquestionably demonstrated (somehow…) that the turtles can live 50 to 80 years. The photograph above is of an Eastern Box Turtle collected in Rhode Island in 1953 with the dates ‘1844’ and ‘1860’ carved into the plastron, implying it was over 100 years of age (Oliver 1955). It is not clear what happened to this individual. Oliver (1955) credits Eastern Box Turtles with a maximum known age of 138 years, but how this was determined is left unsaid.

As for whether or not Box Turtles are abnormal, Congdon (2003) claimed that “evidence for senescence in turtles is weak” and found that Painted Turtles (Chrysemys picta) lived to at least 61 and increased offspring quality with age. I suspect that Box Turtles are not unusually long-lived but rather just easier to mark and recapture. This makes me wonder about some of the turtles I see out basking or cruising on a regular basis, and just how much living they’ve experienced.

References:

Congdon, J. et al. (2003) Testing hypotheses of aging in long-lived painted turtles (Chrysemys picta). Experimental Gerontology 38, 765–772. Available.

Ernst, C. H. & Lovich, J. E. (2009) Turtles of the United States & Canada. John Hopkins University Press.

Henry, P. (2003) The eastern box turtle at the Patuxent Wildlife Research Center 1940s to the present: another view. Experimental Gerontology 38(7), 773–776.

Miller, J. (2001) Escaping senescence: demographic data from the three-toed box turtle (Terrapene carolina triunguis). Experimental Gerontology 36(4-6), 829-32.

Oliver, J. (1955) The Natural History of North American Amphibians and Reptiles. D. Van Nostrand Company.

Picture of the Day – Salty Snapping Turtle

Popular literature frequently claims Diamondback Terrapins (Malaclemys terrapin) are the only US turtles to inhabit brackish waters (e.g. Brennessel 2006) however it would be more accurate to say that terrapins are the species most adapted for brackish conditions. Several other US turtles can occur in brackish waters and some populations of Common Snapping Turtles (Chelydra serpentina) and Eastern Mud Turtles (Kinosternon subrubrum) are apparently adapted for brackish conditions (Ernst and Lovich 2009). I found the almost-hatchling-sized (SCL 3.5 cm) snapper pictured above (literally) beached and lying motionless in a pile of Bladderwrack, which made me wonder if it was in the best condition. Hatchlings can grow well in brackish water, but not beyond 14.35 ppt (Dunson 1986); the snapper I found was near water with a salinity of 22-25 ppt and was hundreds of meters from the mouth of a tidal stream. I reasoned that the turtle would probably not have survived much longer and decided to give it a head-start, getting it as large as possible over the summer and then releasing it into the tidal stream where it would have a better chance of successfully osmoregulating and avoiding predation.

 

References:

Brennessel, B. (2006) Diamonds in the Marsh: A Natural History of the Diamondback Terrapin. University Press of New England

Dunson, W. A. (1986) Estuarine populations of the snapping turtle (Chelydra) as a model for the evolution of marine adaptations in reptiles. Copeia 1986, 741-756.

Ernst, C. & Lovich, J. (2009) Turtles of the United States and Canada. John Hopkins University Press.

Stupendemys

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 PodocnemididaeErymnochelys and 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.

Freakishly Big Eyes

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 atlanticusThe 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 phylluraMegalocranchia fisheriOnykia robustaTaningia danaeDosidicus 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.