Why are there no gigantic insects alive today?
A) There is no niche for gigantic insects.
B) There are gigantic insects in remote regions of the tropics; we just have not discovered them.
C) The concentration of oxygen in the atmosphere is too low to make gigantic body size in insects efficient.
D) There is no evidence of gigantic insects in the past, so there can not be any alive today due to constraining evolution.

Question

Quizplus · Accepted Answer

The size of insects is limited by the way they breathe, through spiracles and tracheal tubes, which is less efficient at higher body sizes, especially in today's lower oxygen concentration atmosphere compared to past geological periods when larger insects existed.

Why Are There No Gigantic Insects Alive Today