Alien arthropod - Stinger

Part of a series of creatures I'm working on in relation to this.

A streamlined, predatory creature. Adapted for life underwater as well as land, its larger rear legs function as paddles. The stinger on the long, whip-like tail features a detachable barb like that of a stingray. During mating season, males will drop their barb in favor of the grasping orifice used in mating rituals and combat over the right to do so.