The extraordinary design of the bombardier beetle - A classic example of biomimetics

Abstract

The innocuous looking bombardier beetle is one of the most remarkable creatures in the insect world. This tiny insect (1-1.5 cms long) is able to fight off any spider, frog, ant or bird that comes too close, by blasting the attacker with a powerful jet of hot, toxic fluid. Furthermore, the beetle can aim its weapon in any direction (even over its head) with pinpoint accuracy, and can reach distances of up to 20 cm with its spray. The bombardier beetle is rare in Europe but common in Africa, Asia and the warmer parts of the Americas, and in order to resist predators, forms a noxious spray by reacting small amounts of hydroquinone with hydrogen peroxide in a pair of combustion chambers in its abdomen, and in the presence of the catalysts catalase and peroxidase. The beetle demonstrates irreducible complexity in the following systems: 1) the sensory mechanism which gives awareness of the approach of a predator, 2) the valve system that involves both inlet and exhaust valves working synchronously, 3) the chemical production of reactants hydrogen peroxide and hydroquinone, 4) the use of catalytic chemistry to eject a controlled explosive mixture, and 5) the moveable, flexible exhaust turret to enable ejection in any direction. These and others are systems which only work when each of the component parts are operating in harmony with others in a coordinated mechanism. For chemical systems the same point applies in principle. The overall chemical system will only operate correctly if each component chemical is in place in a prepared pathway. This paper reviews the research of a number of authors (including Professor McIntosh) into the workings of the bombardier beetle spray system. Not only is this is a classic example of biomimetics (the study of design in nature and copying these designs and using them in engineering), but also tacitly underlines the necessity of design in the original beetle itself. The discovery that the McIntosh team made of sophisticated mechanisms in the beetle's structure and chemistry demonstrates the irreducible complexity in the design of the beetle.