Turtle Shell - Carapace

The carapace is the dorsal (back), convex part of the shell structure of a turtle, consisting of the animal's ribcage combined with dermal bone. The spine and ribs are fused to dermal plates beneath the skin which interlock to form a hard shell. Exterior to the skin the shell is covered by scutes, which are horny plates made of keratin that protect the shell from scrapes and bruises. A keel, a ridge that runs from front to the back of the animal is present in some species, these may be single, paired or even three rows of them. In most turtles the shell is relatively uniform in structure, species variation in general shape and color being the main differences. However the soft shell turtles, pig-nose turtles and the leatherback sea turtle have lost the scutes and reduced the ossification of the shell. This leaves the shell covered only by skin. These are all highly aquatic forms.

In the figure to the right, the exploded shell view, the roman numerals and other notations are as follows:

(i) Neural 1, (ii) Neural 2, (iii) Neural 3, (iv) Neural 4, (v) Neural 5, (vi) Neural 6, (vii) Neural 7, (viii) Neural 8, (ix) extra neural, divided, (x) suprapygal, (xi) nuchal, (xii) right peripheral 1, (xiii) right peripheral 2,

(xiv) right peripheral 3, (xv) right peripheral 4, (xvi) right peripheral 5, (xvii) right peripheral 6, (xviii) right peripheral 7, (xix) right peripheral 8, (xx) right peripheral 9, (xxi) right peripheral 10, (xxii) right peripheral 11, (xxiii) pygal, (xxiv) left peripheral 11, (xxv) left peripheral 10, (xxvi) left peripheral 9, (xxvii) left peripheral 8, (xxviii) left peripheral 7, (xxix) left peripheral 6, xxx left peripheral 5, xxxi left peripheral 4, (xxxii) left peripheral 3, (xxxiii) left peripheral 2, (xxxiv) left peripheral 1, (xxxv) right 1st rib, (xxxvi) right pleural 1, (xxxvii) right pleural 2, (xxxviii) right pleural 3, (xxxix) right pleural 4, (xl) right pleural 5, (xli) right pleural 6, (xlii) right pleural 7, (xliii) right pleural 8, (xliv) right 10th rib, (xlv) left 1st rib, (xlvi) left pleural 1, (xlvii) left pleural 2, (xlviii) left pleural 3, (xlix) left pleural 4, (l) left pleural 5, (li) left pleural 6, (lii) left pleural 7, (liii) left pleural 8, (liv) left 10th rib, (9-18) centrums.