The Basics

Scientists love to use long and complicated names to describe various things. Whilst this can lead to different scientists understanding one another, it also makes relatively easy concepts incomprehensible to the lay person! I've provided some of the basics to scorpion morphology here, but another excellent website is http://www.ub.ntnu.no/scorpion-files/

Scorpions are ARTHROPODS, this means that they do not have bones, but instead have a segmented shell covering their jointed body and limbs. The Arthropoda includes spiders, ants, crabs and millipedes, each of which belong to a diffent group within the Arthropoda. The group of arthropods to which the scorpions and spiders belong is the CHELICERATA, this basically means that the body can be split into 2 major parts and instead of antennae (like all other arthropods), the 1st pair of limbs are modified into pincer-like jaws (chelae/ chelicerae).

The 2 main parts of a chelicerate are the PROSOMA (Head) and OPISTHOSOMA (Rest of the animal). However, if you look at a scorpion, you can see that the opisthosoma can in turn be split into a body (MESOsoma) and tail (METAsoma).

PROSOMA: This contains the chelicerae and the limbs that have been modified into pincers to help with catching food (PEDIPALPS). On the top (dorsal) side is the CARAPACE and EYES. on the bottom (ventral) side are all the LEGS and STERNUM.

MESOSOMA: This is made up from 7 segments. The BOOK LUNGS and GENITAL OPERCULUM and PECTENS are located on the mesosoma.

METASOMA: This has 5 tubular segments and the sting ACULEUS (just for confusion, this is also known as the telson). The anus is located on the 5th segment.