The Scorpion is built from the Lego Spike Prime educational kit. Scorpion can move forward (backward) and can rotate. A distance sensor is installed in the front part. When the scorpion faces an object in front of it, the sensor is triggered and activates the tail. A crank mechanism causes the tail to move back and forth.
The set includes step-by-step building instruction and an example of program (in Spike environment)