Question

Number of segments in the anal cerci of Cockroach is
A. 12
B. 15
C. 18
D. 10

Answer 1

On the end of the abdomen of a cockroach, there is a pair of cerci, projections which are sensory organs. Anal cerci are a pair of appendages at the end of the abdomen, arising from near the 10th segment of the body of cockroach.

Complete Answer:
Cockroach has an extended set of antennae that support them to get smells and vibrations. The antennae are attached to the head that also contains the brain, strong mouth portion for scraping and swallowing food and compound eyes. They have weak visuals and do not like light. That is the reason why most of them are nocturnal.

Now, let us find the solution from the option.
- The abdomen bears 8 pairs of stigmata, anus and a pair of anal cerci. Anal cerci are initiated from the link between 9th and 1Oth segments on the dorsal side one on every side.
- The total number of segments present in anal cercus 15.
- They occur in both male and female cockroaches. They are regarded as the appendages of the vestigial eleventh segment.
- Therefore the number of segments in the anal cerci of Cockroach is 15.

Thus, the correct option is B. i.e. 15.

Note: The abdomen of a cockroach is the final piece, and it contains reproductive organs. At the back of the abdomen are two short protrusions called cerci. They function like rear antennae and are connected to the roach's legs by the abdominal nerve ganglia. This permits their legs to begin working when vibrations are sensed, quickly before their brain even gets a signal. That is also why it can be hard to catch while moving.