Which order is characterized by three long tail filaments and often has adults that do not feed?

Which order is characterized by three long tail filaments and often has adults that do not feed?

• A. Ephemeroptera
• B. Diplura
• C. Thysanura
• D. Protura

Answer: (A)

In this trait set, the key idea is tail morphology paired with adult feeding behavior. Mayflies carry three long tail filaments (caudal filaments) at the end of the abdomen, a distinctive feature of Ephemeroptera. Their adults typically have mouthparts that are vestigial or not functional, so they do not feed and live only a short time to mate and disperse. This combination—three long tails and non-feeding adults—best defines this order. Diplura and Protura don’t have this three-tail pattern (Protura lack tails, Diplura have two cerci), and while some bristletails (Thysanura) have three filaments, their adults usually do feed, unlike mayflies.

In this trait set, the key idea is tail morphology paired with adult feeding behavior. Mayflies carry three long tail filaments (caudal filaments) at the end of the abdomen, a distinctive feature of Ephemeroptera. Their adults typically have mouthparts that are vestigial or not functional, so they do not feed and live only a short time to mate and disperse. This combination—three long tails and non-feeding adults—best defines this order. Diplura and Protura don’t have this three-tail pattern (Protura lack tails, Diplura have two cerci), and while some bristletails (Thysanura) have three filaments, their adults usually do feed, unlike mayflies.