Pyramiding & Star Tortoises
Natural or poor husbandry?
Sri Lankan Star tortoise (Geochelone elegans)
Metabolic bone disease
In captivity, many young, growing tortoises become "lumpy" due to less than ideal husbandry. Various reasons have been suggested as possible explanations for this, for example, too much protein, too much food, too dry conditions, not enough calcium, lack of sunlight or vitamin D3, and not enough exercise.
Tortoises that have flattened, extremely bumpy, and unnatural looking shells have metabolic bone disease (MBD). MBD is alarmingly common among captive tortoises due to poor nutrition and husbandry practices.
In advanced cases, the whole tortoise looks grossly deformed. The carapace typically slopes down towards the tail. Jaws may be deformed. Limbs may be swollen. The tortoise may be lame and unable to lift itself off the ground.
If you are acquiring a tortoise, be sure to research the proper diet and care for your species to help prevent this devastating and debilitating condition.
Now, Indian Star tortoises can have MBD if they are not properly cared for, but many of them also have slightly conical scutes without exhibiting any other signs or deformities of MBD.
Indian / Sri Lankan Star tortoises (Geochelone elegans)
Indian / Sri Lankan Star tortoises may have smooth or bumpy carapaces. Other than lumpiness caused by poor captive conditions, no one seems to know yet for sure why some of them have bumpier shells than others. Explanations for shell lumpiness in the G. elegans range from genetics to the effects of geographical location to variations in diet.
Tortoise keepers are debating if the lumpiness truly is a natural condition among Star tortoises or caused by environmental factors. However, most reptile books, new and old, describe the Indian Star tortoise as having conical scutes.
1.) Books - Indian Star tortoise shell descriptions:
Günther writes in 1864 (Reptiles of British India) about the Testudo elegans (now Geochelone elegans), the Starred Tortoise: "In many adult specimens the single plates are more or less elevated into prominent humps, the height of which may be from half an inch to an inch. This peculiar form is so frequently found, that we cannot consider it as a monstrosity, but rather as an indication of very great age."
In Tortoises, Terrapins and Turtles Drawn from Life by James de Carle Sowerby and Edward Lear (1872), the Testudo actinodes (now G. elegans) description says: "It varies greatly in the number of yellow rays, and in the flatness and convexity of the dorsal shields."
In his 1890 book Reptilia and Batrachia: Fauna of British India, including Ceylon and Burma, Boulenger describes the Testudo elegans with words: "Carapace very convex, dorsal shields often forming humps." The accompanying black-and-white drawing shows an Indian Star tortoise with slightly raised scutes (pic below).
Reptilia And Batrachia: The Fauna Of British India Including Ceylon And Burma, Boulenger 1890 (US-PD)
Richard Lydekker describes the "Elegant Tortoise" in his 1896 book The Royal Natural History: Reptiles, amphibians, fishes, the lowest vertebrates and their allies with words: "Frequently, moreover, the shields of the back are swollen, so as to form more or less prominent bosses." (pic below)
Elegant tortoise. The Royal Natural History: Reptiles, amphibians, fishes, the lowest vertebrates and their allies, Volume 5 of The Royal Natural History, Richard Lydekker, 1896. (google books, public domain)
Malcolm M. Smith's famous book The Fauna of British India, Reptilia and Amphibia, Vol I, was published in 1933 in London. He wrote: "... the vertebral and costal shields forming distinct, sometimes very marked, humps in the adult ..." He also mentions that the amount of bumpiness varies among individuals. (see books page)
Highfield (Practical Encyclopedia of Keeping and Breeding Tortoises and Freshwater Turtles, 1996, UK) documents that the coning of vertebrals and costals is very variable within the G. elegans species. He suggests it may be related to the geographical origin of the animal.
Sharma (The fauna of India and the Adjacent Countries, 1998, India) writes that vertebral and costal scutes "form well marked conical humps in adults."
Dr. Hartmut Wilke writes in his 2000 book Tortoises and Box Turtles about the Indian Star tortoise: "... develop quite pronounced horny pyramids on the individual scutes in advanced age. This is not a sign of illness."
Daniel (The Book of Indian Reptiles and Amphibians, 2002, India) identifies the Indian Star tortoise with the description "domed carapace has conspicuous humps."
Anslem de Silva (The Biology and Status of the Star Tortoise, 2003, Sri Lanka) states that the vertebrals are humped in some Sri Lankan Stars and that this bumpiness varies greatly among individuals.
Susan Donoghue, MS, DMD, DACVN, writes about pyramiding in the book Reptile Medicine and Surgery (2006, Mader, MS, DVM, DABVP) and mentions that "a few tortoise species grow naturally conical scutes, mimicking pyramiding." For these species, e.g. Geochelone elegans, this type of carapace is normal.
According to Bidmon (Turtles: Proceedings: International Turtle & Tortoise Symposium Vienna 2002, 2006, Germany), slightly raised, pyramidal scutes are a naturally occurring phenomen within all populations of G. elegans. It is not necessarily a sign of poor nutrition. However, the pyramiding of scutes is also effected by food and humidity. He does not believe the conical scutes are inherited, but are influenced by microclimate, type and amount of food, dominant behavior, and stress. Environmental changes in the wild could be a reason for pyramided shells in wild individuals.
Fife (Star Tortoises, 2007, US) mentions in his Star tortoise book that Indian Stars are generally smooth in nature. The book includes a photo of an Indian Star with shell deformities (abnormal growth) taken by a veterinarian.
I also have several books written by Das (India, books), but he does not describe if the shells in the wild G. elegans are generally smooth or pyramided. The photos in his books show Indian Stars with mild to moderate lumpiness. They are not perfectly smooth.
2.) Web - Indian Star tortoise shell descriptions:
Wiesner & Iben of the University of Veterinary Medicine in Vienna (2003, Austria) write "With very few exceptions (e.g. Geochelone elegans, Psammobates sp.) this conical growth pattern is considered pathological and occurs mostly in tortoises in captivity."
Dr. Chris Tabaka and Darrell Senneke of WCT (2003, US) write that Indian Star tortoises may have smooth or bumpy carapaces. The reason for this natural pyramiding (conical scutes) is unknown, but the raised scutes do make it easier for the tortoise to right itself on flat ground when it becomes overturned. They further state: "If higher domed and bumpier Star tortoises had a greater survival rate because of this, the tendency to a pyramided appearance would be selected for in future generations."
A while back I read a posting on the King Snake tortoise discussion board written by Dr. William Zovickian (2007), an experienced Star tortoise breeder, where he states that many Sri Lankan Star tortoises exhibit pyramiding in the wild (unlike other tortoises). His theory was that this may be due to some inbreeding because the gene pool on the Sri Lankan island has been restricted for thousands of years.
In a 2008 RFUK forum post, Andy Highfield (Tortoise Trust, UK) writes that he has seen hundreds of x-rays of pyramided tortoise shells, and he's never seen a pyramided tortoise that didn't have metabolic bone disease. Having said that, he states that this excludes Indian Star tortoises and African starred tortoises where conical scute formation is genetic. He then writes: "Despite the 'pyramid' or tent-like structure of the vertebral scutes on these, the bone density is entirely normal and no lesions are present."
I have also heard from some other Indian / Sri Lankan Star tortoise breeders that Sri Lankan Stars will generally pyramid (grow conical scutes) to some degree no matter what one does. Even if they are raised under identical conditions as smoother shelled Indian Stars.
Many believe that Sri Lankan Stars, and possibly Stars from north-western India, tend to be more susceptible to coning than Indian Stars from southern India. In Stars, females and dominant tortoises may be more pyramided as well. This more extensive pyramiding is possibly due to their faster growth.
The conical scutes in Indian / Sri Lankan Star tortoises look similar, but not identical, to diseased pyramiding (MBD). However, even this is debatable. Some people say all pyramiding in tortoises is a form of MBD, while others differentiate between "natural" pyramiding (as in Stars) and MBD.
Caution though, not every pyramided Indian / Sri Lankan Star is a healthy tortoise with "naturally" conical scutes. The tortoise may actually have MBD due to improper care. Learn what a sick tortoise with MBD deformities looks like, so that you can differentiate the two.
Peltastes platynotus [Geochelone platynota], Blyth 1863 (US-PD)
Proceedings of the Zoological Society of London 1870
Burmese Star tortoises (Geochelone platynota)
In the wild, Burmese Star tortoises have smoother carapaces than Indian Star tortoises. Thus, Burmese Stars are also called Flatback tortoises, meaning they have smooth and flat shells. When raised in captivity, they do often pyramid somewhat.
Günther quotes Blyth in his 1864 reptile book (Reptiles of British India) about the Testudo platynotus (now G. platynota): "Very similar to T. stellata [now G. elegans], but averaging a larger size, and conspicuously distinguished by being quite flat on the back, the plates not rising in the center [as in G. elegans]." This same description is found in volume 32 of the Journal of Asiatic Society of Bengal (Calcutta, 1864).
In 1933, Malcolm A. Smith (The Fauna of British India, including Ceylon and Burma. Reptilia and Amphibia. Vol. I.) also describes the Burmese Star tortoise with words "the vertebral and costal shields not humped."
Dr. Peter Liu wrote on his Burmese Star web site (2000, site gone) that the carapace of most Burmese Star tortoises is oval, domed, and generally flattened without pyramiding. However, based on his observations, he theorized that about 10% of the wild Burmese Star tortoises may be pyramided. In addition, he raised some Burmese Star tortoises that became pyramided under the same diet and environmental conditions as his smooth shelled Burmese Stars. He suggested that this pyramiding may be due to genetics.
TSA's (Turtle Survival Alliance) 2009 e-magazine has photos of Burmese Star tortoises in captive breeding programs in Myanmar (formerly Burma). Some of these tortoises have smooth shells and some have bumpy shells.
This Burmese Star tortoise is pyramided. Pyramiding refers to the lumpiness of the shell. The shape of each bumpy shell scute resembles a small pyramid. It's usually caused by less than ideal husbandry practices. Unlike some Indian / Sri Lankan Star tortoises, wild Burmese Stars do not typically have conical scutes, but they may have a slight rise in the middle of the scutes. (photo by Am Wu Photography)
African starred tortoises (Psammobates)
Africa has its own starred tortoises. Tent tortoises (Psammobates tentorius), Geometric tortoises (P. geometricus), and Serrated tortoises (P. oculifer) have beautiful star-patterned carapaces.
According to Branch (Tortoises, Terrapins & Turtles of Africa, 2008, South Africa) Serrated tortoises have slightly raised carapace scutes, Tent tortoises have flat or conical scutes depending on the subspecies, and Geometric tortoises have raised cone-like scutes. In fact, the Tent tortoises were named after the conical, tent-like vertebral and costal scutes. Tentorium is Latin for tent.
In the photos, the pyramiding (conical scutes) in these African starred tortoises ranges from mildly raised scutes to severely conical. The appearance is very similar to that of Indian / Sri Lankan Star tortoises.
So far, nobody seems to know for sure how to best prevent pyramiding in captive-bred and -raised tortoises. However, many experienced tortoise keepers believe adequate humidity and hydration as babies and youngsters may be the answer. Higher ambient humidity, frequent drinking, regular soaks, warm mistings, and humid hides are beneficial, especially during the first 1-2 years.
Also, adequate sunshine, a suitable diet (enough fiber, nutrients, calcium etc.), sufficient exercise, and low-stress environment are important for tortoises' general health.
Plus, as explained above, in some Star tortoises, the "pyramided look" may possibly have a genetic component to it.
Update: In Nov 2010, Andy Highfield of Tortoise Trust published a summary of his study on pyramiding [offsite] in tortoises.
Examples of normal and abnormal shell growth
X-ray of a smooth tortoise carapace (top shell)
X-ray of a pyramided tortoise carapace (top shell)
I have not found any cross-sectional photo of an Indian / Sri Lankan Star tortoise's carapace online. Per Tortoise Trust (see above), the bone of a healthy G. elegans has normal bone density even if the scutes are conical. Anyone have such a photo to share? Or know of one posted on the web?
Photos of pyramided shells cut open
- Shelled Warriors - UK bb, photos of the insides of pyramided and healthy, flat tortoise shells; in the cross-section photos you can see the porousness of pyramided bone
- Testudo Farm - German site, photos of two pyramided tortoise shells sawn open along the longitudinal axis; one has thick and porous bone and the other one doesn't
- Tortoise Forum - US bb, cut off photos of a pyramided shell
- Tortoise Forum - US bb, cross-section photos of normal (dense bone) and pyramided (porous bone) shell, Nov 2010
- Tortoise Forum - US bb, pyramided Leopard tortoise shell cut open, Jan 2011
- Tortoise Trust - UK bb, cross-section of a pyramided shell, compare to a healthy shell, Feb/Mar 2010
More about pyramiding (various opinions)
- African Tortoise - Pyramiding in Tortoises, by Joe Heinen
- African Tortoise - Metabolic Bone Disease, by Joe Heinen
- AZ Exotic Animal Hospital - Pyramiding in tortoises
- Reptile Channel - Pyramiding in tortoises, by Richard Fife
- Riparian Farms - Pyramiding in tortoises, by Richard Fife
- Testudo Farm - Formation of humps in the shell of European tortoises, by Wolfgang Wegehaupt. He writes that perfectly smooth shells are only found in original habitats that have not undergone any alterations by man. He does not believe ambient moisture and humidity level is the main cause of pyramiding. Captive tortoises must drink enough water regularly. As an example, he mentions tortoises that were kept on dry substrate and in low humidity, but grew up with smooth shells because they were soaked routinely (same link as above).
- Tortoise Trust - Promoting Proper Bone Development, by A.C. Highfield
- Tortoise Trust - UK bb, discussion of pyramiding in Star tortoises, photos by A.C. Highfield, Feb 2010
- Tortoise Trust - The causes of “Pyramiding” deformity in tortoises: A summary of a lecture given to the Sociedad Herpetologica Velenciana Congreso Tortugas on October 30 2010, by A.C. Highfield, Nov 2010 (keratin, bone, natural burrows, humidity, heat lamps, wear & tear, etc.)
- Univ of Vienna - Influence of environmental humidity and dietary protein on pyramidal growth of carapaces in African spurred tortoises (Geochelone sulcata), by Wiesner & Iben, 2003, full text pdf file; abstract is available at PubMed
- WCT - World Chelonian Trust, What Causes Pyramiding, by Darrell Senneke, 2004