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 f ossil whose fundamental morphology has been unchanged f or 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 f eeding regime of T. cancriformis was f ound to be related to the f auna and f lora of the temporary pools. Invertebrates and animal detritus were f ound 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 f emale and there was only one male among 400 samples collected. Observation of sperm among f ollicle ducts of a f ew samples indicated some degree of hermaphrodity, but the animal seemed to reproduce mainly through parthenogenesis. Fecundity, varying f rom 100 to 2500 cysts, was with a f ew exceptions related to the body size. The average cyst diameter was 400± 85 μ m