Earnest Griggs, Age 16, of oxford, Ga., for his question:
How do insects breathe?
Most experts agree that life exists on many other planets. We long to know what or who our spacemen will find when they visit other worlds. We can guess away to our heart's content. But no native of Sirius or Polaris could be more amazing than the insects that share our home planet with us.
The thousands of different insects far outnumber the entire assortment of other animals in the world. The bitsy creatures differ frmm each other in many ways, but all of them are vastly different from all other earth dwellers. Every insect, however, has three pairs of stalky legs and a body of three distinct sections head, thorax and abdomen.
Like other earthlings, an insect uses Oxygen. A few insects take oxygen from the water, but the average insect gets his oxygen from the air. The air enters through pores called spiracles arranged in pairs along the sides of his body. He may have two pairs of spiracles on his thorax and six or eight pairs on his abdomen. Each pair is on a segment of the insect's body.
The air seeps through the spiracles into air tubes called tracheae. The tracheae branch into smaller tracheoles which spread throughout the cell tissue of the insect's soft insides. The working cells take the Oxygen they need to carry on their life processes. They return waste carbon dioxide to the air in tracheoles and tracheae. Eventually, the waste gases seep out through the spiracles.
The blood of an insect has no red hemoglobin to carry oxygen to the cells. The Oxygen is made available by the fine, thin walled tubes that carry air between and among the cells. The insect can control his supply of air by opening and closing spiracles. This is important in hot weather when the dry air outdoors could evaporate
His vital body fluids sometimes several pairs of spiracles are closed to control supply of air entering and leaving the body.
Insect blood may be a clear liquid or colored pale green or yellow. The bitsy creature has a heart and a circulatory system of sorts, but no blood vessels. The blood fills cavities in the body. The heart is a long tube placed where you would expect to find a spine. The tube is punctured with holes along the sides and open at both ends. It is lined with fibrous muscles which keep it pulsing, drawing blood through the sides and sending it out through the ends. The circulating blood, however, has nothing to do with respiration as it does in the red blooded mammals.