Sulcata tortoise: does pyramiding really come from protein? What a study found
Published by Planète Pets · managing editor: Clément Lacaille · how our guides are written
Pyramiding — the shell scutes that bulge into peaks instead of staying flat — affects a large share of captive-raised sulcata tortoises (Centrochelys sulcata), and almost never their wild counterparts. The most commonly cited cause is excess dietary protein. A study by Wiesner and Iben, published in 2003 in the Journal of Animal Physiology and Animal Nutrition, tested that factor against another one, and the result nuances the tidy explanation (, doi 10.1046/j.1439-0396.2003.00411.x). Find our other pointers in the reptile food section.
Contents · 6 sections
Two factors tested side by side
The authors raised young sulcata tortoises under different humidity levels and dietary protein contents, then measured the severity of pyramiding produced by each combination. The goal was to find out which of the two factors, or which one primarily, explains the shell distortion so common in captivity.
Humidity comes out as the dominant factor
The study's headline result is that low ambient humidity emerged as the factor most strongly linked to pyramiding, more so than dietary protein content. In other words, a tortoise raised in air that was too dry pyramided noticeably, even on an otherwise reasonable protein intake.
A belief to nuance, not to discard
This result does not mean diet plays no role at all: chronic excess protein remains inadvisable for a strict herbivore, for reasons beyond pyramiding alone (kidney load, overly fast growth). It mainly shows that fixing the bowl alone, without also addressing the terrarium's or outdoor enclosure's humidity, is unlikely to be enough to prevent the phenomenon.
What the study does not show
The work was carried out on a small number of young tortoises, and its protocol has faced methodological criticism in later discussions, particularly over how tightly other growth variables were controlled. It also does not establish one precise, universal optimal humidity level: that also depends on the enclosure's temperature and ventilation.
What this changes in practice
For a young specimen of this fast-growing species, humidity and access to a moist substrate deserve at least as much attention as the ration's protein content, alongside growth that is neither too fast nor too slow. Our guidance on sulcata tortoise growth in captivity details the setup to plan accordingly.
Frequently asked questions
Does pyramiding go away if the diet is fixed later?
No: once the bulging scutes have formed, they stay that way permanently. The only effective lever is prevention, from the first months of growth.
So should protein be ignored altogether in a herbivorous tortoise?
No, chronic excess is still worth avoiding for the animal's general health; the study simply shows that humidity weighs at least as heavily on pyramiding. Find all our guides on the reptile hub.
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This guide is part of Planète Pets’s Reptiles universe. Our advice is general in nature: for any health concern, your veterinarian remains the only reference.