The Astacus leptodactylus specimens were collected from four sites of Aras reservoir, North-West of Iran and examined for the epibionts during 2009. Protozoan epibionts from ciliophora (one genus and seven species) and tracheophyta were isolated from the cuticular surface of different body parts of narrow-claw crayfish, A.leptodactylus. Seasonal prevalence of infestation was determined in 394 i...

We examined relationships between individual differences in antipredator behaviour and prey morphological characters (size, shape) that influence prey vulnerability. Behavioural responses of Physa gyrina to chemical cues associated with predation by crayfish Orconectes rusticus, were assayed in the laboratory for 6 days over a 13-day period. Snails displayed consistent, individually repeatable ...

The emission spectra calibration curves for a fluorescence indicator and the F(min), F(max), and K(d) formula were shown to be related. Using the known calibrated fluorescence emitted by Sodium Green (Na-Green) and photo-multiplier-tube quantum efficiency, we calculated the detection signal over a range of sodium concentrations. The calculated calibration curves were compared for optical filter...

showing sclerites at base of limbs. Note that first and last pair of appendages are clawed. Fig. i.?Male (X44). Ventral surface, showing sclerites at base of limbs. Note that first and last pair of appendages are clawed.