Copepods

Copepods have a variety of sensory capabilities. The most noteworthy are bristle-like setae that act as mechanoreceptors responding to flow that causes bending. An array of such sensors allows detection of patterns of water flow around the body caused by approaching prey or predator, and the copepod can distinguish between the two. The sensors are highly specialized for sensitivity and the nerves are even myelinated for fast conduction.
The second pair of antennae are the main source of propulsion, beating like oars to pull the animal through the water.