Animal Kingdom Question 113
113. If the head of cockroach is removed, it may live for few days because
(a) the cockroach does not have nervous system.
(b) the head holds a small proportion of a nervous system while the rest is situated along the ventral part of its body.
(c) the head holds a $1 / 3^{\text{rd }}$ of a nervous system while the rest is situated along the dorsal part of its body.
(d) the supra-oesophageal ganglia of the cockroach are situated in ventral part of abdomen.
Show Answer
Answer : b
Hints & Solutions
(b) Cockroaches breathe passively through a network of pipes connected to holes called spiracles along the length of their body. They are independent of blood circulation to move oxygen around and their body fluids are at a much lower pressure. The sensory input from the eyes and antennae, along with many other behaviours, are transmitted and handled by their brain such as running and reacting to touch, handled by ‘mini brains’ called ganglia in each body segment. A decapitated cockroach will eventually starve to death but this can still take few days. Cockroaches also have a higher tolerance for radiation than other animals (especially compared to humans), though this would only help them survive the longer-term radioactive contamination that could follow a nuclear blast.
