Some Biological Characteristics of Tadpole Shrimp, Triops cancriformis, from Seasonal Pools of West Azarbaijan (Iran)

The tadpole shrimp of genus Triops is a well-known living fossil whose fundamental morphology has been unchanged for 220 million years. We collected specimens of Triops cancriformis in temporary water bodies near the southern part of Urmia Lake (in the Fall of 2005). Some biological characteristics of this Triops were investigated. The feeding regime of T. cancriformis was found to be related to the fauna and flora of the temporary pools. Invertebrates and animal detritus were found to constitute major part of the feeding regime. The existence of Triops cysts and particles in the gut also showed certain degree of cannibalism. Morphological and histological investigations showed that the population of T. cancriformis was female and there was only one male among 400 samples collected. Observation of sperm among follicle ducts of a few samples indicated some degree of hermaphrodity, but the animal seemed to reproduce mainly through parthenogenesis. Fecundity, varying from 100 to 2500 cysts, was with a few exceptions related to the body size. The average cyst diameter was 400±85 mm