A scorpion is an invertebrate animal, meaning it does not possess a backbone or an internal skeleton made of bone or cartilage. This classification is determined by the creature’s internal structure and primary form of support. Scorpions, along with 97% of all animal species, are grouped into the division of animals that lack a vertebral column.
Understanding the Classification of Animals
The animal kingdom is broadly divided into two major groups based on skeletal anatomy: vertebrates and invertebrates. Vertebrates are defined by the presence of a vertebral column, commonly known as a backbone or spine, which is part of an internal skeleton called an endoskeleton. This structure provides the main support for the body and protects the central nervous system. Examples of vertebrates include mammals, birds, fish, reptiles, and amphibians.
In contrast, invertebrates are animals that do not possess a vertebral column. This group is incredibly diverse, encompassing nearly all animal life on Earth, and exhibits a wide variety of body plans. Many invertebrates, like worms and jellyfish, have soft bodies with no hard skeleton. Others, such as insects and crustaceans, rely on a hard outer shell for support. This core difference in skeletal architecture is the defining trait for animal classification.
Why Scorpions Are Not Vertebrates
Scorpions fall into the invertebrate category because they lack a spinal column and internal bony skeleton. Instead of an endoskeleton, the scorpion’s body is supported by a rigid, external structure called an exoskeleton, composed primarily of chitin. This casing provides both protection and a surface for muscle attachment, performing the functions of internal bones in vertebrates.
The scorpion’s body is distinctly segmented, divided into two main sections: the cephalothorax (prosoma) and the abdomen (opisthosoma). The exoskeleton is not a single piece but rather a system of hard, connected plates that allow for necessary movement and articulation. Scorpions must periodically shed their exoskeleton in a process called molting to increase in size.
Scorpions and the World of Arthropods
The scientific classification of the scorpion places it within the Phylum Arthropoda, the largest phylum in the animal kingdom, which includes all invertebrates with jointed legs and segmented bodies. All arthropods share the features of a segmented body, paired jointed appendages, and the chitinous exoskeleton.
Within the Arthropoda phylum, scorpions belong to the Class Arachnida, a group that also includes spiders, ticks, and mites. Arachnids are distinguished from insects by having four pairs of walking legs, totaling eight, and lacking antennae. Scorpions possess specialized mouthparts called chelicerae and a pair of large, clawed appendages known as pedipalps, which are used for capturing and holding prey.