Morphometric study of certain inland water copepods from Nashik, Maharashtra, India

The morphometric study of selected copepods was carried out during year 2018 from Godavari river of Nashik region. In the present study, a total of four copepod genera were selected for carrying out their morphometric measurements in terms of micron. These are Mesocyclops sps, Macrocyclops fuscus, Tropocyclops prasinus and Eucyclops agilis. The morphometry of various body parts like cephalosome, metasome, urosome, antennae, caudal rami, fural rami and total body length were measured by using ocular micrometer scale. On the basis of measurement obtained in the present study, it can be concluded that Eucyclops is the largest of all, Macrocyclops and Tropocyclops are intermediate in size whereas, Mesocyclops is the smallest of all studied specimens.

Weak swimming response of a bdelloid rotifer to chemical cues of a native copepod predator

Whether bdelloid rotifers can detect and respond to the chemical cues of predators has not been studied, and research on their behaviour is scarce in general. To test for such response, we observed the behaviour of Philodina megalotrocha rotifers in either control or copepod-conditioned water. We then introduced a mechanical disturbance to test if predator odour sensitises rotifers to subsequent cues. We found intensified swimming in P. megalotrocha exposed to Macrocyclops fuscus-conditioned water, i.e. the larger and more predatory of the tested copepods. Such response may be adaptive, depending on the predominant hunting mode of the predator in the particular habitat.