Giant bugs need more oxygen, according to a report from the American Physiological Society, 11 October 2006. The largest living beetle is a long horned beetle with the impressive scientific name of Titanus giganteus. It can grow to be 15-17 cm long. However, the fossil record contains much larger insects. Scientists have suggested the reason for this is that the atmosphere could have contained up to 35% oxygen in the past compared with the present oxygen content of about 21%. To see whether oxygen availability is an insect growth limiting factor, a team of researchers led by Alexander Kaiser of Midwestern University, Arizona studied the size of breathing tubes in beetles in different sized beetles in comparison to their overall body size. Insects take in oxygen through holes named spiracles, which are connected to a system of tubes named trachea. As insects grow larger they need longer, wider trachea to provide enough oxygen for their bodies and legs. They found in the largest beetles studied the trachea were 20% larger in proportion to their size, compared with the smallest. This is because the tubes have to be not just longer but wider, to deliver enough oxygen. However, there is a limit to how big the opening can be in the connection between leg and body. The researchers concluded that in the present atmosphere, beetles could not grow much larger than 15 cm if they depended on the spiracle system to supply oxygen. However, they could grow larger if there was more oxygen in the atmosphere as they would not need larger spiracles in proportion to their body size.
Editorial Comment: This study, along with the fossil record of Giant Dragon flies, spiders, cockroaches, etc, reminds us the world was once a much better place to live. More oxygen is good for many kinds of living things, and we know from the fossil record, insects weren’t the only creatures that grew larger in the past. The giant insects flew among giant plants and giant animals. This fits with Genesis, which describes a world of created perfection, where everything was “very good” that degenerated because of human sin and God’s judgement. (Ref. air, giants, arthropods)
Evidence News 25th October 2006