what are some unique physical characteristics of a scorpion

Main physical features

Pedipalps: the long front appendages that end in the so-called "claws" (the correct term is chelae or "pincers"). Some believe these were originally legs that were modified during evolution. The pedipalps are used primarily for prey capture but also play an important part in the scorpion mating dance. They are made of up of six segments. The chela (pincer) itself consists of the upper fixed finger (tibia) and the lower movable finger (tarsus). The pincers' size is highly dependent on the species; however, a general trend is that the more venomous the scorpion, the narrower the pincers, as scorpions with less potent venom use their larger pincers to subdue prey.

Pectines: these are a pair of feather-like sensory organs, consisting of a row of pegs, and are unique in scorpions. The pectines are located beneath the scorpion, attached to the sternum. They constantly touch the ground and play an important role in the scorpion's sensory equipment. The pectines are covered in thousands of chemosensors that allow the scorpion to detect minute chemical signals in their environment; they probably play an important role in social interaction, mating and hunting.

Eyes: fossil scorpions had compound eyes, modern scorpions in general have three sets of eyes. One pair located in the top centre of the carapace are called the median eyes. There are two more sets of lateral eyes on either side of the front of prosoma, the number varies between species. In total, there are usually from three and up to six pairs of eyes present. Some species of cave- and litter-dwelling scorpions, however, have no eyes, relying purely on their other senses. Scorpions' eyes are primitive organs, only able to detect regions of strongly contrasting light intensity, such as horizons. The eyes, however, are very sensitive; some have theorised that they even allow the scorpion to navigate by star light and help regulate the scorpion's circadian rhythm. It is doubtful as to whether they are used in prey capture.