ScienceAsia 29 (2003): 095-098 |doi: 10.2306/scienceasia1513-1874.2003.29.095

Eggshell Structure of the Siamese Narrow-headed Softshell Turtle Chitra chitra Nutphand, 1986 (Testudines: Trionychidae)

Wachira Kitimasak^a,b,*, Kumthorn Thirakhupt^a and Don L Moll^c

ABSTRACT: Eggs of Chitra chitra were examined for: 1) eggshell thickness by stereo-microscope, 2) eggshell structure by scanning electron microscopy (SEM), 3) qualitative and quantitative elements of eggshell structure by energy dispersive x-ray analysis (EDX), and 4) eggshell composition by X-ray diffraction analysis. It was found that the eggshell thickness of the outer layer and inner layer detected by stereomicroscope were 0.140.02 mm and 0.120.02 mm, respectively. The result of SEM showed that the eggshell had three layers; an outer calcareous sheet (previously unseen), a middle crystalline layer, and an inner fibrous layer. The eggshells were composed of oxygen=53.04.8%, carbon=35.09.2%, magnesium=5.550.34%, calcium=5.47.2%, silica=2.91.6%, aluminum=2.31.1%, potassium=0.170.1%, and sodium=0.740.3%. The eggshell was the aragonite form of CaCO₃.

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a Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330 Thailand.
b Kanchanaburi Inland Fisheries Development Center, Tha Muang, Kanchanaburi Province
71110 Thailand.
c Department of Biology, Southwest Missouri State University, Springfield, Missouri 65804 USA.

* Corresponding author, Email: wachira@chula.com

Received 7 Jon 2003, Accepted 20 Feb 2003