Tortoise Shell Scutes
- carapace & plastron -
Vertebral scutes on a Golden Greek tortoise
A tortoise's bony shell is covered with a layer of scutes (plates, shields, scales). These scutes do not correspond in size or shape to the bones below them. Scute attributes can be used to identify tortoises.
A typical tortoise (land turtle) has 5 vertebrals, 4 right and left costals, 11 right and left marginals, 1 nuchal scute, and 1 supracaudal scute.
A typical tortoise has a pair of gulars, a pair of humerals, a pair of pectorals, a pair of abdominals, a pair of femorals, and a pair of anal scutes.
In many tortoise species, the male has a longer tail, a concave plastron, curved-in supracaudal scute, and sometimes a more angular anal notch (angle between the anal scutes). Each species has its own gender characteristics though.
Angulate tortoise shells
I used the shell of an Angulate / Angulated tortoise (Chersina angulata) as my model for these illustrations. Just like a typical tortoise, the Angulate tortoise carapace has 5 vertebrals, 4 pairs of costals, 10-12 right and left marginals, 1 small nuchal, and a single undivided supracaudal scute.
However, the plastron of the Angulate tortoise has a unique feature: a single, protruding gular scute (throat shield). This scute gives the species its popular name Bowsprit tortoise. Bowsprit is the long pole in the front of a sailing ship. The Angulate tortoise also has a pair of humerals, a pair of pectorals, a pair of abdominals, a pair of femorals, and a pair of anal scutes.
Angulate carapace (top shell)
Angulate plastron (bottom shell)