Soft and hard-shelled eggs of Caiman latirostris

FERNÁNDEZ, MARIELA S.; LARRIERA, ALEJANDRO; SIMONCINI, MELINA S.

Manila

Congreso; XXI Working Meeting Crocodiles Specialist Group; 2012

Crocodiles Specialist Group - UICN

We report the first record of abnormal eggshells (soft-shelled and hard-shelled eggs) in nests of the Broad-snouted caiman. These eggs were collected in Santa Fe province, Argentina. The eggs were collected from nests in nature and captivity. Two different types of abnormalities were identified, i.e., 1. hard-shelled eggs, among which can be distinguished (1a) eggs exhibiting a wrinkled texture that occurs in circles around one pole and (1b) aggregates calcitic grains on the eggshell surface; and 2. soft-shelled eggs. The inner portion of the shell units that comprise the eggshell is interrupted (2), producing gaps that weaken the shell. These soft-shelled eggs lack the hard and continuous shell wall present in normal eggs. Some nests containing recently laid clutches included eggs with most of the eggshell broken and detached from the flexible membrane. In C. latirostris, most hard-shelled eggs, those with the granular texture (1b) could be lost during incubation, even dissapear on the end of that process. Therefore, the granular texture presence in earlier stages of development does not directly affect the embryos survival. Soft eggs of C. latirostris studied here (2), have mean hatching success of 8.9 % (range 0% to 38%). Most of the eggs loss is probably due to infections (by fungi and bacteria).