By Geetha G T – I want to talk to you about something you do all the time…What is that? Yes, breathing! It just happens. Just think that there are an enormous number of insects on this earth that also breathe – but differently!
The respiratory system of insects is different from the circulatory system. Insects don’t use lungs like us to breathe, they depend completely on a property of physics termed a concentration gradient. When concentration gradients arise, molecules move from spaces of high to low concentration to retain an equilibrium between the two spaces. This is what actually happens in the insect respiratory system. They use a network of small tubes called tracheae. The air enters the tracheae through a row of holes along the abdomen called spiracles. From the tracheae, air diffuses into very thin tubes called tracheoles, where the exchange of atmospheric air and cells occurs.
Similar to all arthropods, insects have an open circulatory system as opposed to our closed circulatory system, where the blood is held within blood vessels. Insect blood, called hemolymph, circulates throughout the body cavity. The function of hemolymph is to circulate vital nutrients, essential salts and important hormones throughout the insect body. And it also helps retain body shape and assists in the insect’s movement. Interestingly, the hydrostatic pressure created by contractions of the heart also aids in functions such as emerging, molting, and reproduction!
Want to see an insect heart in action? Watch the video below closely. You should be able to see the vessel of each insect expand and contract in their own way!