Sherwin Dueck, age 11, of Janow, Manitoba, Canada, for his question:
Does an insect have a brain?
Every insect has a trigger sharp brain, though it is not the right kind of brain for thinking. The bitsy creature does not have to solve problems as we do. His actions and reactions are governed by built in instructions inherited from his ancestors. His fairy like body is a living miracle and his tiny brain is designed to guide him through his pre arranged life cycle usually at top speed.
In all animals, the brain is the headquarters of the nervous system. It receives multitudes of messages from the sense organs, sifts them and flashes back instructions for suitable action. The branching nerves carry all this data to and fro in the form of electrical impulses. A brain, even the bitsy brain of a tiny insect, is a complex biochemical switchboard. It is his vital control center and it is well protected.
An insect has no internal skeleton so his brain is not encased in a bony skull. However, he is encased in chitin, a tough shielding that serves his small body better than bones. His brain is shielded in a snug helmet of chitin. It is a mass of soft nerve cells linked to ganglia and nerves that branch through his body. A ganglion is a bundle of nerves, somewhat like a trunk line. The average insect has two main ganglia running lengthwise along his body, somewhat similar to the human spinal column.
Streams of nerve impulses flash to his brain. Some are prompted by internal needs, such as hunger, others relay external news via his sense organs. An insect’s eyes never close and the sensory nerves on his antennae never rest. Chances are, he has small sensory pegs and bristles on his mouth parts. As a rule, he can detect the tiniest traces of odor and taste, touch and often vibrations. Some insects have hearing organs in the abdomen, feet or legs. None have ears in their heads and apparently many of them are stone deaf.
An insect’s brain copes.with this data in a flash. It is programmed to respond to each situation in a set pattern. The blueprint is in the DNA inherited from his ancestors. His brain is not built to consider the facts and decide what to do. Each bit of information triggers a certain course of action and the insect must obey.
Suppose a fly is quietly primping when she senses an approaching swatter. Sensory impulses flash this news to her bitsy brain which orders a fast take off, up and away.
This sudden take off is a highly complex maneuver, involving the co ordinated action of many muscles. It is possible because her simplified brain is programmed to trigger a set reaction to the situation. The fly has no choice. Her survival depends on instant and accurate obedience.
The senses of insects are very different from ours and there are surprising variations in different species. This calls for variations in their brains and sensory nervous systems. Probably no two species are exactly alike. But basically, the brains of all insects work on the same simplified trigger system.