What term describes mouthparts that are directed posteriorly?

What term describes mouthparts that are directed posteriorly?

• A. Hypognathous
• B. Prognathous
• C. Orthognathous
• D. Opisthognathous

Answer: (D)

In insect mouthpart terminology, orientation refers to which direction the mouthparts point relative to the head. When mouthparts are directed toward the back of the insect, that arrangement is described as opisthognathous. The prefix opistho- means behind or posterior, so this term literally signals “mouthparts toward the rear.” This contrasts with other directions: prognathous mouthparts project forward from the face, hypognathous mouthparts point downward, and orthognathous mouthparts extend straight out in line with the head. Because the question specifies a posterior (backward) direction, opisthognathous is the precise term.

In insect mouthpart terminology, orientation refers to which direction the mouthparts point relative to the head. When mouthparts are directed toward the back of the insect, that arrangement is described as opisthognathous. The prefix opistho- means behind or posterior, so this term literally signals “mouthparts toward the rear.”

This contrasts with other directions: prognathous mouthparts project forward from the face, hypognathous mouthparts point downward, and orthognathous mouthparts extend straight out in line with the head. Because the question specifies a posterior (backward) direction, opisthognathous is the precise term.