Question

In cockroach, the audio receptors are situated on
A. On legs
B. Antenna
C. Sensory receptor
D. Anal cerci

Answer 1

Hint: Cockroaches can sense sounds and motions using a part that is situated at their posterior side of the body. These parts project out of the cockroach’s body and look similar to appendages. These structures help the cockroach to escape from a predator or avoid something as simple as a shoe being thrown at them.

Complete answer:
In cockroaches, the audio receptors are present on the anal cerci. The anal cerci are projections present on the rear side of the body of a cockroach. They are present in a pair and act as sensory organs.

The anal cerci are able to pick up vibrations from the surroundings (air and ground) and signal it to the cockroach so that it can take the necessary action. The cerci are connected to the legs through the abdominal nerve ganglia. The abdominal nerve ganglia act as a second brain for the cockroach. Once the cerci pick up vibrations, the cockroach can start running even before the signal reaches the brain. This is because the cerci are connected to the legs.

Hence, the correct answer is option (D).

Additional information:
• Antennae: the antennae are also sensory organs that help the cockroach to sense smell, thermal changes, and humidity.
• Legs: three pairs of legs are present on the thorax of the cockroach which helps them in running at high speeds

Note: The anal cerci help the cockroach in developing an escape mechanism. The anal cerci contain small sensory hair that generates a response when air or wind comes from a particular direction. In order to escape, cockroaches run at high speeds and are even able to defy the laws of gravity by crawling up the walls and ceilings.