Dragonflies have a round head and quite large relative to their body covered largely by two large double eyes, legs that can easily catch prey while in flight. The flanks are similar, long, thin, and nearly transparent, and move independently. The vein system is very thick, many intricate, complex dashed ribs, the anterior end of the wing usually has a wing eye that is a regulator to suppress mechanical vibration, ensuring a firm wing. The belly is long. Oral crushed organs, with slender legs facing forward. Beard is small, has two segments and a small, long hairs segment. Anus appendages on the third, fourth (in males) and second (in females) segments; genital organs in the ninth abdominal burning; secondary copulatory organ on the second (in males).
The world’s largest dragonfly species today is the Central American giant dragonfly, Megaloprepus coerulatus and Anax strenuus, a species of dragonfly endemic to the Hawaiian Islands. In the past, there was a dragonfly with a wingspan of 60 cm long, fossils dating back 285 million years.