Its not fair, and its not at all accurate.
Here we look at just one aspect of turtle anatomy.
Well, wait a goddam minute… Ok, here we go.
Theyre also present in squamates, archosaurs and turtles.
This phylogenetic distribution has led some authors to conclude that these organs were present in amniote common ancestors.
Note how different the organs are in their cross-sectional structure.
An intromittent organ of this sort is typically termed a penis.
Its single erectile body is divided into a collagenous corpus fibrosum and a highly vascularized, expandable corpus spongiosum.
Even an uninflated penis tucked away inside the cloaca is large.
More on the issue of size later on.
Bishop & Kendall (1929) found that turtle penis retractor muscles were physiologically rugged and of extreme endurance.
Her publications can be obtained, free, from her homepagehere.
Anterior and posterior pairs of sinuses are also present on the upper surface of the glans.
However you respond to these images, dont feel ashamed.
Some of the configurations involved look terrifying; others look really terrifying.
The penis as a whole is seemingly simplest in sea turtles*.
Here, the glans is pointed, with the seminal groove terminating in a single, deep fold.
In many species, theres a pointed medial process at the tip of the glans.
Carettochelys is odd in lacking sinuses on its penis.
Softshell turtles (Trionychidae) go one (or two) better, since their glans is five-lobed.
Softshell turtles thus discharge semen from four distinct branches of the seminal groove.
This might leave you wondering what the insides of a female softshells cloaca are like.
Thats an issue I should discuss some other time.
1997, Hirayama et al.
2000), all of which have complex penises.
What little data Ive seen (e.g., Cabral et al.
It really is large and formidable in some species.
(Featured here are giant tortoises mating.
Photo by Minglex, licensed under Creative Commons Attribution 3.0 Unported license.)
So, small turtles can have proportionally huge organs.
What about big turtles?
Unfortunately, little data is available.
If you have useful data, c’mon say so!
Sea turtles are another group of turtles famous for reaching large size.
Surely they have large penises.
Hold your hands 30 cm apart and think about that enormous penis for just a moment.
What about the Leathery turtle Dermochelys coriacea?
Unfortunately, I missed it when it was on and havent been able to see it yet.
Joy Reidenberg told me at the time that the male individual they examined was, indeed, well endowed.
As you could see from the two screen-shots shown here, she wasnt kidding.
This may or may not mean something for penis anatomy, but I dont think well ever know.
It is a sight to behold, and one that can startle both novice and experienced herpetoculturalists alike.
The organ itself is large in proportion to the turtle, and dark purple in color.
After several seconds, the turtle will retract the organ back through the cloaca.
It may repeat this process once or twice.
I also note the very interesting paper by de Solla et al.
[Adjacent photo credited to/r/Pics].
And that is just about everything I know about turtle penises.
To those of you for whom this information is new…
I trust that youll never look at a turtle in the same way again.
This post byDarren Naishoriginally appeared atScientific AmericansTetrapod Zoology.
He mostly works on Cretaceous dinosaurs and pterosaurs but has an avid interest in all things tetrapod.
He has been blogging atTetrapod Zoologysince 2006.
References
Bishop, G. H. & Kendall, A. I. American Journal of Physiology 88, 77-86.
Anatomy of the male reproductive system of Phrynops geoffroanus (Testudines: Chelidae).
Penis displays of common snapping turtles (Chelydra serpentina) in response to handling: defensive or displacement behaviour?
Chelonian Conservation and Biology 4, 187-189.
Gadow, H. 1887.
Remarks on the cloaca and on the copulatory organs of the Amniota.
Philosophical Transactions of the Royal Society of London B 178, 5-37.
Gaffney, E. S. & Meylan, P. A.
A phylogeny of turtles.
In Benton, M. J.
(ed) The Phylogeny and Classification of the Tetrapods, Volume 1: Amphibians, Reptiles, Birds.
Clarendon Press (Oxford), pp.
Hamann, M., Limpus, C. J.
& Owens, D. W. 2003.
Reproductive cycles of males and females.
In Lutz, P. L., Musick, J.
& Wyneken, J.
(eds) The Biology of Sea Turtles, Vol.
CRC Press, Boca Raton (Florida), pp.
Hirayama, R., Brinkman, D. B.
& I. G. Danilov.
Distribution and biogeography of non-marine Cretaceous turtles.
Russian Journal of Herpetology 7, 181-198.
Honda, M. 2001.
Art Journal 60 (2), 96-100.
Isles, T. E. 2009.
The socio-sexual behaviour of extant archosaurs: implications for understanding dinosaur behaviour.
Historical Biology 21, 139-214.
James, M. C. 2004.
Dermochelys coriacea (Leatherback sea turtle).
Herpetological Review 35, 264-265.
Joyce, W. G. 2007.
Phylogenetic relationships of Mesozoic turtles.
Bulletin of the Peabody Museum of Natural History 48, 3-102
Kelly, D. A. Axial orthogonal fiber reinforcement in the penis of the nine banded armadillo (Dasypus novemcinctus).
Journal of Morphology 233, 249-255
Kelly, D. (2002).
The Functional Morphology of Penile Erection: Tissue Designs for Increasing and Maintaining Stiffness.
Integrative and Comparative Biology, 42 (2), 216-221 DOI: 10.1093/icb/42.2.216
.
Turtle and mammal penis designs are anatomically convergent.
Proceedings of the Royal Society of London B 271 (Suppl 5), S293-S295.
McCracken, K. G. 2000.
The 20-cm spiny penis of the Argentine lake duck (Oxyura vittata).
Petterer, E. & Neuville, H. 1914.
Du penis et du clitoris des crocodiles et des tortues.
Rendu Hebdomadaire des Seances et Memoires de la Societe de Biologie, Paris 76, 101-103.
Shaffer, H. B., Meylan, P. & McKnight, M. L. 1997.
Tests of turtle phylogeny: Molecular, morphological, and paleontological approaches.
Systematic Biology 46, 235-268.
Zug, G. R. 1966.
The penial morphology and the relationships of cryptodiran turtles.
Occasional Papers of the Museum of Zoology, University of Michigan 647, 1-24.
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