Posted by Hatka Hatnaa Posted on 7:43:00 AM
The anatomy of scorpions has changed little since the Silurian Period (443 to 417 million
years ago). Consequently, their body plan is relatively primitive. Segments and associated structures were lost or fused during evolution from ancestral arthropods and arachnids to more highly evolved descendants. Scorpions have more segments (18) than any other arachnids and are strongly segmented in the design of the heart and nervous system. The possession of book lungs rather than tracheae for respiration is also primitive.The vast majority of scorpions are nonsocial, solitary animals that interact only at birth, during courtship, or for cannibalism. They are often so aggressive that they are usually considered “inveterate cannibals.” A few, however, exhibit social behaviour. Some overwinter in aggregations with individuals of their own species, usually under bark or in fallen trees. A few extend the mother-offspring association for weeks to months or even years. In some cases (e.g., emperor scorpions) offspring may remain with the family group even as adults, and some of these family groups cooperate in prey capture.