Question

Anal cerci occur in
a. Both male and female cockroaches
b. Male cockroach
c. Female cockroach
d. Female Ascaris

Answer 1

Hint: The anal styles (male copulatory organs) are only present in the male cockroaches. The anal cerci are sensory organ, which are wind sensitive. In cockroaches, exoskeleton is made up of chitin.

Complete answer:
- Cockroaches are nocturnal, omnivores that are included in Class Insecta of Phylum Arthropoda.
- The body of cockroach is 34-53mm long, segmented, and divisible into 3 regions- head, thorax and abdomen.
- The entire body is covered by a chitinous exoskeleton. Each segment contains its own chitinous layer called sclerites (dorsally tergites, ventrally sternites and laterally pleuritis). These hard plates are joined together by a thin arthrodial membrane.
- Head is triangular in shape and bears compound eyes, antennae and mouthparts. The mouth parts consist of labrum, mandibles, maxillae, labium and hypopharynx. Antennae are sensory in nature.
- Thorax consists of prothorax, mesothorax and metathorax. Prothorax contains the neck. Each thoracic segment contains legs. Wings arise from mesothorax and metathorax.
- The abdomen contains 10 segments. The abdomen in females contains genital pouch, gonopores, spermatheca and collateral glands.
- The abdomen in male contains genital pouch, dorsal anus, male genital pore and gonapophysis.
- In male cockroach, a short, thread-like anal styles are present.
- In both male and female cockroach, a jointed filamentous anal cerci is present.

In cockroach sexual dimorphism is present, the main differences between male and female cockroaches are-
- Male cockroaches are smaller in size as compared to female cockroaches.
- The wings of male cockroach are larger in size as compared to a female cockroach.
- The antennae of male cockroaches are smaller in size than that of female cockroaches.
- In male cockroach, anal styles are present while in female cockroach anal styles are absent.

Hence, The correct answer is option (A).

Note: The labrum, labium and hypopharynx act as upper lip, lower lip and tongue respectively. Spermatheca is an ectodermal female reproductive organ which receives and stores the sperm. The collateral glands help in formation of ootheca.