The Carkta fighter was developed by the Takra species, an aquatic race hostile to Earth. It's design is based on the Carkbas crabs living in the planets oceans, including claws, a similar design of the "shell", and the same graviton based propulsion system. It is capable of being used in space, an atmosphere, or underwater.
A demonstration of the most common method of attack: The fighter's claws are used to grab an enemy fighter, then it is ripped in half, often while being fired at by the laser cannons on each arm. No pilot has ever survived this attack.