Mature aliens have concentrated acid for blood which they know they can use to their advantage. They have two mouths, one inside the other, the inner mouth being the alien's tongue. The tongue can extend up to one foot from the alien's mouth and its strong driving force can easily puncture a human skull. The adult alien develops sharp claws and a spiked tail, which is used for both balance and attack. Spines on the alien's back provide protection from attacks from the rear. Adult aliens are also good swimmers and are equally deadly in and out of the water.