Given the task definition and input, reply with output. Given a scientific passage and an answer, generate a question for the given answer.

Passage: There are several traits shared by all arthropods. Arthropods have a complete digestive system. They also have a circulatory system and a nervous system. In addition, they have special organs for breathing and excreting wastes. Other traits of arthropods include:. Answer: insects
What group of animals are the largest arthropods?