Question

Which of the following is characteristic feature of cockroach regarding sexual dimorphism?

• A. Presence of anal styles
• B. Presence of sclerites
• C. Presence of anal cerci
• D. Dark brown body colour and anal cerci

Answer 1

The Correct Option is A

To answer this question, we need to understand the concept of sexual dimorphism in cockroaches. Sexual dimorphism refers to differences in appearance between males and females of the same species beyond their sexual organs.

In cockroaches, one of the primary features used to distinguish males from females is the presence of anal styles, which are short, finger-like projections found only in males. These structures are located on the ninth abdominal segment, near the anal cerci, which are present in both sexes but more pronounced in males.

Let's evaluate the given options:

• Presence of anal styles: This is a distinct feature in male cockroaches and not found in females, indicating sexual dimorphism. This option is correct.
• Presence of sclerites: Sclerites are hard plates or segments found on the exoskeleton of cockroaches, but they are present in both males and females and do not exhibit sexual dimorphism. This option is incorrect.
• Presence of anal cerci: Anal cerci are found in both male and female cockroaches, although they may be more developed in males. However, their presence alone does not indicate sexual dimorphism. This option is incorrect.
• Dark brown body colour and anal cerci: The dark brown body color is common in cockroaches regardless of sex, and the presence of anal cerci, as discussed, is not exclusive to one sex. This option is incorrect.

Thus, the characteristic feature of sexual dimorphism in cockroaches is indeed the presence of anal styles, which are exclusive to males.